A stacked multi-layer substrate integrated waveguide (SIW) microstrip patch antenna with broadband operating bandwidth and low cross-polarization radiation is provided. A complete study on the propagating element bandwidth and cross polarization level is presented to demonstrate the importance of the design. The proposed antenna includes three stacked printed circuit board (PCB) layers, including one layer for the radiating 2 × 2 rectangular patch elements and two SIW PCB layers for the feeding network. There are two common methods for excitation in cavity-backed patch antennas: probe feeding (PF) and aperture coupling (AC). PF can be used to increase the bandwidth of the antenna. Although this method increases the antenna’s bandwidth, it produces a strong cross-polarized field. The AC method can be used to suppress cross-polarized fields in microstrip patch antennas. As microstrip patch antennas are inherently narrowband, the AC method has little effect on their bandwidth. This paper proposes an antenna that is simultaneously fed by AC and PF. As a result of this innovation, the operating bandwidth of the antenna has increased, and cross-polarization has been reduced. Actually, the combination of probe feeding and aperture coupling schemes leads to achieving a broadband operating bandwidth. The arrangement of radiator elements and cavities implements a mirrored excitation technique while maintaining a low cross-polarization level. In both numerical and experimental solutions, a less than −30 dB cross-polarization level has been achieved for all of the main directions. A fractional impedance bandwidth of 29.8% (10.55–14.25 GHz) for  Microstrip patch antennas (MPAs) are broadly used in various types of applications. These antennas have many advantages like low profile, low cost, and easy integration with other devices ,4,5,6,7.The operating bandwidth of single-feed MPAs could be increased by using thick dielectric materials with low dielectric relative permittivity , creatinMicrostrip lines and coplanar waveguides (CPWs) are often used to feed conventional microstrip patch antenna arrays. The operating bandwidth of conventional MPAs with these planar feeding networks is usually less than 5%. By increasing operating frequency, these planar antennas often face many serious problems and challenges. In particular, in higher frequencies, unwanted radiations have suddenly appeared from the feeding network, and the antenna’s efficiency has increasingly dropped ,20,21,22The radiation efficiency of wireless communication systems is one of the most important parameters that can increase their reliability. The antenna radiation efficiency in satellite and remote-sensing applications is essential due to the inherent losses in long-distance communications. Limiting the antenna’s efficiency can have a direct impact on bandwidth ,24,25 anMPA arrays are commonly fed by microstrip lines. Microstrip lines are typically preferred because they facilitate the routing of low-profile feeding networks. They do, however, introduce unwanted radiation losses, which could have a significant impact on the antenna’s radiation performance and reduce its radiation efficiency.Substrate integrated waveguide (SIW) technology is one of the best alternatives for microstrip lines and CPWs at higher frequencies. Despite the fact that SIWs require more space than microstrip networks, they provide reliable performance at a higher frequency. In recent years, SIW technology has been used for a wide variety of applications due to its advantages, such as low cost, low loss, and ease of integration. Compared to hollow rectangular waveguide structures, SIW structures have many of the same features and similar radiation characteristics, but they are much less expensive. SIW technology, therefore, could be an effective replacement for RWG. Various types of microwave and millimeter-wave components, such as antennas, feeding networks, filters, etc., have been implemented using SIWs ,30,31,32Different strategies have been used to feed MPA with SIW feeding networks. Vertical integration between MPA and an SIW cavity is one of the most effective methods ,34. ThisAlthough, by using the PF method, the impedance characters can be significantly improved, these structures still suffer from high cross-polarization levels ,36. SurfExciting patch radiator elements by the PF method leads to generating strong cross-polarized fields on the antenna surface. These strong cross-polarized fields can degrade antenna performance. Moreover, they may increase back lobe radiation in the radiation patterns or even decrease the antenna radiation efficiency .Using an AC method instead of PF can significantly suppress the cross-polarization levels . In comp0 element spacing, the 2 × 2 proposed array can be easily extended to a large array by using it as a sub-array. Hence, the proposed array could be useful in array applications requiring small element spacing, wide operating bandwidth, and lower cross-polarization levels. This structure has a geometric shape that allows it to be used in a variety of systems, such as monopulse systems, remote sensing, and satellite applications. This paper is organized as follows. In this paper, a microstrip patch array is presented that uses a combination of PF and AC techniques. Using these two techniques simultaneously increases the impedance bandwidth of the proposed design and suppresses its cross-polarization radiations. In the proposed structure, the radiation elements are surrounded by a small space, which results in a compacted structure and higher efficiency. With 0.5 λ0, whereas distance in the H-plane is 11.2 mm, i.e., 0.36 λ0, where λ0 is the free space wavelength at 12.5 GHz.In the proposed design, by using the PF configuration, the microstrip patches are excited. On the common ground between layers 2 and 3, there is a slot, which splits the electromagnetic (EM) power into cavities on the middle layer. In this mechanism, the distance between center to center of adjacent radiating elements in the E-plane is 8.8 mm, i.e., 0.476 λA square topology is used for the EM power distribution network based on four SIW cavities. SIW cavities are formed by inductive windows. This feeding network is designed by considering several primary dimensions as follows. To control the leakage of the EM wave, the diameters of cylindrical metalized holes (vias) are selected by these conditions: S/d ≤ 2, and d/The resonance frequency is determined by the cavity dimensions. The following relationships could be used to calculate the SIW cavity’s initial dimensions: (1)fmnp mnp.f The designed cavities operate when m = n = 1 and p = 0.The resonant frequency of the proposed cavities is determined by rε (=3.55) is the dielectric relative permittivity. The resonant mode for proposed cavities is TE110.Cavity dimensions are represented by the parameters To minimize the leakage in the SIW layers, vias are used with diameter d = 0.8 mm, and the center-to-center spacing between adjacent vias is S = 1.6 mm.After primary calculations, CST Microwave Studio was used to optimize the geometries of the proposed cavities in As shown in To validate the simulated performance of the proposed array, a prototype shown in The appearance of robust cross-polarized fields in the radiation characters of patch antennas is always a fundamental challenge for antenna designers. In the conventional patch antennas, excitation of higher modes with orthogonal polarization causes cross-polarized fields in the H-plane. A cross-polarized field in the H-plane is stronger than in the E-plane. Studies show that in the H-plane of patch antennas within the ±25° beamwidth, the isolation between the co- and cross-polarization radiation is around 10–20 dB ,39.The EM radiation patterns of the proposed MPA are discussed in this section. The work is mainly focused on the study of cross-polarized fields. When investigating the cross-polarization behavior in the antennas, an important point must be considered. Only checking the isolation between co- and cross-polarization patterns in the two main cutting planes of E- and H- is not sufficient to confirm that an antenna has a low cross-polarization level. In antenna characteristics, the cross-polarization level could be extremely low in both the E- and H-planes, while on the other cutting planes, the cross-polarization level could be extremely high. This behavior can exist in various types of antennas. The distribution of the electric fields on the horn antenna’s aperture clearly indicates that on the E- and H-cutting plane, the cross-polarization level is minimal, while on the other orthogonal cutting planes, strong cross-polarization radiation is observed . More riIn this paper, in order to accurately investigate cross-polarization behavior, as well as ensure its low level on all the planes, contour plots are presented. These contour plots indicate the cross-polarization level on different cutting planes. Then, the simulated and measured radiation patterns of the proposed antenna on the cutting planes 𝜙 = 0° (E-plane) and 𝜙 = 90° (H-plane) are presented. In reliable wireless communication systems, the antenna’s efficiency is a significant feature. The impedance bandwidth and gain could be directly limited by this feature. Several single-feed MPA designs have already been proposed. Microstrip lines fed the majority of them. The designs based on microstrip lines present a feasible structure in which the feeding network production is easier while maintaining a low profile. However, as the antenna’s operating frequency rises, the amount of unwanted energy transmission from these feeding lines rises dramatically. This unwanted energy transmission has a significant negative impact on the radiation pattern, resulting in a reduction in radiation efficiency.Antenna radiation efficiency is described by IEEE standards as “the ratio of the total power radiated by an antenna to the net power accepted by the antenna from the connected transmitter” . Dielect2, and it has a maximum realized gain of 11 dBi at 13.5 GHz frequency.The radiation efficiency of large arrays is primarily affected by unwanted radiation and losses from the combinatory feeding structure . It is possible to achieve higher radiation efficiency when minimizing the length of the feeding networks, such as those in series feeding ,46. It dIn terms of frequency bandwidth, the proposed formation presents wideband radiation elements like the magneto-electric dipole , L-probeA single-element X-band patch antenna is presented in  and fed A comparison between various characteristics of the proposed design and previously reported results in terms of the number of layers, antenna size, operation frequency, impedance bandwidth, and cross-polarization level are provided in In , a 4 × 4In , the AP 20 to TE10. The impedance bandwidth of this five-layer antenna is 12.9%. The used feeding network in this structure is complex. Moreover, the number of PCB layers will be increased by developing this structure to a large array.In , a two-lThere are advantages of the proposed structure can overcome many of the challenges associated with previous designs. This manuscript presents a 2 × 2 array of a broadband MPA with low cross-polarization levels. The presented structure has several features. First, a combination of PF and AC methods has been used to feed this structure. PF allows us to control impedance characters and achieve a higher impedance matching. The experimental results indicate that the operating bandwidth of this MPA array is 29.8%. On the other hand, the aperture coupling method has helped us to provide a very effective mechanism for suppressing cross-polarization without the need to design complex power distribution networks. The reduced cross-polarization is studied for a 3-D half-power beamwidth space. The measured results show that the cross-polarization level for the presented MPA is less than 30 dB in the whole operating impedance bandwidth. The designed array can be easily used as a subarray to design larger arrays. This does not need to increase the number of PCB layers to design larger arrays. The proposed array does not require the use of blind screws or even internal connections and its fabrication process is simple.0 element spacing, the proposed 2 × 2 array can be easily used as a sub-array to design a large array. Hence, the proposed array could be useful in applications requiring small element spacing, wide operating bandwidth, and lower cross-polarization levels. It has good potential to use the proposed structure as a subarray in a larger array for a wide spectrum of practical applications such as satellite remote-sensing antennas.A successful combination of aperture coupling and probe feeding methods is demonstrated in this paper. The main advantages of this compact package are its broadband character and low cross-polarization levels. A mirrored geometry between radiating elements and the feeding network is used to create the 2 × 2 array. This design occupies less space around the radiation elements, which reduces the size of the antenna and improves its efficiency. In this study, the suppressed cross polarization is verified for a 3-D half power beamwidth area in the whole operating bandwidth (10.55–14.25 GHz). For all of the main directions, the cross-polarization level is less than −30 dB. With a 0.5 λ


Simultaneously enhancing multiple antenna performance parameters is a demanding task, especially with a challenging set of design goals. In this paper, by carefully deriving a compatible set of enhancement techniques, we propose a compact/lightweight/low-cost high-performance L-band octagonal cavity-backed hybrid antenna with multiple attractive features: dual-polarization, wide impedance bandwidth, low cross-polarization, high gain, and high aperture efficiency. The ground cavity is octagonal, which allows the antenna to have a small footprint, and, more importantly, low cross-polarization and high aperture efficiencies when compared to a commonly-used square design. The hybrid design relies on the resonance merging of two radiating elements, i.e., radiating feedlines and a conductive open prism, to form a wide impedance bandwidth. To permit polarization diversity and low cross-polarization, it is differentially and orthogonally fed. Herein, a series of parametric simulation studies on antenna configurations provide information on how to improve the impedance bandwidth and cross-polarization performance. To verify the simulation studies, an antenna prototype was fabricated and tested. Excellent agreement between the simulated and measured results was reached. An antenna, as one of the key components in a wireless device, has a vital impact on device performance. To fulfill the requirements of the application for which the antenna is used, a certain set of antenna performance parameters needs to be met. Simultaneously enhancing multiple antenna performance parameters can be challenging but necessary for many applications. On an individual basis, performance enhancement on single parameters has been studied, and numerous enhancement techniques have been developed. However, it takes specialized methods, such as those discussed in this manuscript, to achieve high performance for multiple parameters while not sacrificing the gains made in the enhancement of individual factors. In this paper, we propose a compact/lightweight/low-cost, high-performance antenna with a challenging combination of qualities: polarization diversity, wide impedance bandwidth, high gain with stable broadside radiation, low cross-polarization, and high aperture efficiency. Such an antenna is desirable for many applications, including remote sensing and satellite communications.Impedance bandwidth enhancement is often one of the first steps in antenna optimization. Two of the most widely used techniques are parasitic element loading ,2,3,4 anGain enhancement approaches include: forming an array , using aExisting cross-polarization reduction techniques include feed designing ,17 and sThis paper proposes a novel high-performance dual-polarized antenna that can be used for many applications, such as remote sensing and satellite communication, where compact antennas with low cross-polarization are required. Alternatives are corrugated horns that are bulky, heavy, and very costly to fabricate. The key antenna parameters are determined to broaden the bandwidth of the antenna simultaneously for the impedance, high gain, high aperture efficiency, and low cross-polarization, which results in the most compact antenna size. Simultaneous improvement of multiple antenna performance parameters was achieved by carefully selecting and deriving a compatible set of performance enhancement techniques. The design considerations and the basic antenna configuration are presented in Our goal was to develop a novel dual-polarized antenna design that can provide wide impedance bandwidth, high gain with stable broadside radiation, low cross-polarization, and high aperture efficiency. Based on , we set A typical antenna design includes three major parts: ground, primary radiator, and feed. Based on the above-mentioned characteristics of interest, some of the basic design considerations are laid out below.Due to its capacity for providing high gain with stable broadside radiation across a wide operating frequency band, a cavity-backed configuration was adopted for this design . With a A basic ground cavity is formed by adding vertical sidewalls on all the edges of a conventional planar ground plane. Therefore, the shape of a ground cavity is dictated by that of the horizontal base of the cavity. One of the most frequently used planar ground planes is square in shape, and as a result, ground cavities with square ,11 apertTo achieve a wide impedance bandwidth, a hybrid design with multiple radiators was developed. To simplify the design, the feed structure was configured to serve as the extra radiator. Together with the primary radiator, they produce multiple adjacent resonances, which can be merged to form a wide bandwidth. The overall impedance bandwidth due to the resonance merging depends on the bandwidth of each individual radiator. Therefore, individual radiators having a wide bandwidth is advantageous to the overall bandwidth enhancement. To keep the design process simple, this work mainly focused on deriving a wideband primary radiator.For a compact antenna, the primary radiator needs to be compact while simultaneously providing sufficiently long current paths on the feedlines, thereby permitting them to be efficient radiators. This can be achieved using a 3D radiator instead of a planar one. Due to its folded sides, a 3D radiator has a smaller footprint but supports longer current paths. Since the primary radiator is backed by a ground cavity with sidewalls, the use of a 3D radiator does not necessarily lead to a bigger overall antenna profile . To support wideband or multiband operation, multiple current paths of different lengths should be allowed on the primary radiator . This reCommonly used feeding structures include coaxial probes and printed feedlines. Both types of feeding structures can excite an antenna through direct contact or proximity coupling. With proximity coupling, the primary radiator is excited through the gap between it and the feeding structure. This allows a higher degree of freedom for tuning the impedance matching of the primary radiator and the resonant frequency of the feedline. Therefore, proximity coupling was adopted. Compared to a coaxial probe, a printed feedline has additional degrees of freedom to match an antenna, such as the shape and the width of the feedline. In addition, a printed feedline with a potentially larger width can provide stronger coupling than a coaxial probe with a limited diameter. Hence, in this work, we used printed lines as the feeding structure. To realize dual-polarized operation, the feedlines are placed orthogonally along the X- and Y-axes. To suppress cross-polarization, differential feeding was implemented. By adjusting the excitation/matching conditions of the orthogonal differential pairs, three dual-polarization schemes, namely dual-linear, slant dual-linear, and dual-circular polarizations, could be realized.As established previously, in addition to its role in exciting the primary radiator, the feeding structure in this design needs to act as a broadside radiator at a close enough frequency to that of the primary radiator to allow resonance merging. The feedlines were suspended above the horizontal base of the ground cavity to provide broadside radiation. One end of each feedline is connected to an excitation port located in the ground cavity sidewall, while the other end is open to provide proximity coupling to the primary radiator . This way, the feedlines act as physically wide horizontal monopole antennas connected to a vertical ground plane and backed by a horizontal ground plane. Their large width makes them broadband capable. gL) was 165 mm, the cavity height (swH) was 80 mm, the gap between the lower dielectric layer and the ground plane (g) was 11 mm, and the spacing between the feedline and the radiating prism (s) was 3 mm. The feedline lengths and widths (l and w) were 53 mm and 30 mm, respectively. The transition feedline lengths and widths (l’ and w’) were 1 mm and 3.6 mm, respectively. These values were selected to make the antenna operate in the L-band (1–2 GHz) with a resonance merging effect.Based on the above design considerations, we propose a novel design—a dual-polarized octagonal cavity-backed antenna with two orthogonal pairs of differential feedlines that excite a radiating open prism in the center of the cavity. We call this design an “octagonal cavity-backed open radiating prism,” or OCROP. Our antenna consists of four parts: (1) a conductive octagonal-shaped cavity, (2) a conductive radiating open prism, (3) two orthogonal pairs of differential feedlines, and (4) a supporting dielectric substrate. The geometry is shown in L = W, to allow geometrical symmetry and identical performance in two orthogonal polarizations of interest. For the antenna to operate in the L-band (1–2 GHz) around a center frequency of 1.5 GHz, the dimensions of the open prism were set to L = W = H = 51 mm, forming a cube with no bottom face . This value was found through simulation studies that are not included here for brevity.We considered numerous design configurations and performed parametric simulation studies to test the concepts. Since the antenna was designed for dual-polarized operation, the length and the width of the open prism needed to be the same, i.e., The numerical simulations throughout this study were performed using ANSYS Electronics Desktop 2021 R1©. Lumped port excitations with a constant full port impedance of 50 Ω were assigned to all four ports. In the following studies, only the Y-polarized differential pair was excited with equal amplitude and 180° out-of-phase signals, while the X-polarized differential pair was terminated with 50 Ω matched loads. Since the antenna is symmetric, X- and Y-polarizations have identical performance.gL = 165 mm, swH = 80 mm, g = 11 mm, s = 3 mm, l = 53 mm, w = 30 mm, l’ = 1 mm, and w’ = 3.6 mm. dd11 ≤ −10 dB impedance bandwidth: the one with the square ground cavity has an impedance bandwidth of 54.0%, and the one with the octagonal ground cavity has an impedance bandwidth of 54.3%. The gain and diagonal-plane cross-polarization of the two antennas are compared in To verify the superiority of an octagonal ground cavity a over a Our design attains wide impedance bandwidth by using multiple radiators that have adjacent resonances and similar radiation patterns . These radiators are the open prism and the feedlines. gL = 165 mm, swH = 80 mm, g = 11 mm, s = 3 mm, l = 53 mm, w = 30 mm, l’ = 1 mm, and w’ = 3.6 mm. As can be seen, the differential reflection coefficient for the antenna without the open prism  is much wider than the cross-polarization bandwidth . For instance, the -impedance bandwidth for the case As can be seen, at this stage, the impedance bandwidth  and cavity height (swH). Since the excitation ports of the antenna are located on the cavity sidewalls, the feedline length is directly correlated with the aperture length. In other words, the impedance bandwidth is very sensitive to changes in the aperture length. To improve the radiation performance with minimal impact on its impedance bandwidth, here, we only investigate the effect of the ground cavity sidewall height. To determine this, we varied the sidewall height swH from 70 mm to 140 mm in 10 mm increments while keeping all other antenna dimensions constant .For a cavity-backed antenna, its radiation performance is heavily dependent on the ground cavity . Two keydd11) results for different sidewall heights are shown in dd11 ≤ −10 dB are Simulated differential reflection coefficient  cross-polarization ratio is shown in dd11 ≤ −10 dB) decreases while cross-polarization bandwidth (for X-pol ≤ −25 dB) increases. In column 4, we present the combined bandwidth, where we took the minimum and maximum frequencies that met both requirements. In all cases, the lower frequency bound, swH ≤ 90 mm and the cross-polarization bandwidth for swH ≥ 100 mm. Once the sidewall height reaches 90 mm, there is very little change in the overall operating bandwidth (42.7 ± 0.7%).The bandwidth of operation is summarized in g = 11 mm and swH = 80 mm, at 1.5 GHz on a fictitious square surface with a length of 4 λ, located 1 λ above the aperture, as shown in The aperture field distribution for the antenna, with In this section, we present measurement results from a prototype of the OCROP antenna. We start by presenting the feeding network, which was formed with a 180° hybrid coupler. Next, we present the reflection coefficient and radiation pattern measurements for the prototype antenna to verify their performance with respect to the simulations.In practice, we require a differential feed when using the antenna and measuring radiation patterns. Therefore, two types of measurements are required.First, we needed to establish the differential S-parameters to compare the simulated and fabricated designs. The two-port VNA in our lab only supports single-ended S-parameter measurements. Since two of the ports are fed simultaneously, we cannot simply use the standard S-parameter measurement approach . Additionally, we cannot measure the differential reflection coefficients in our lab using the two-port VNA. Therefore, to characterize the differential feed, we measured the single-ended S-parameters at all ports  and calculated the differential reflection coefficients using an established approach .Secondly, to use the antenna in practice, we need to provide a single input and a feed network. This is required in our facility to measure the radiation pattern, as the receiver has a single port for measurement. Therefore, we measured the input reflection coefficient, as seen at the input to the combination of the feeding network and antenna together. These results are presented in this section.Ideal differential feeding requires equal amplitude  and 180° phase difference at the two differential ports. This was easily realized in HFSS simulation by setting up the correct amplitude/phase for each excitation port and assigning differential pairs. In measurement, a feed network shown in  was consSince the antenna ports are in the sidewalls of the ground cavity, we used 90° angled SMA connectors to eliminate the stress of the cable mass on the prototype, and these were used to connect the antenna to the feed network. Without the phase trimmers, the phase difference between the signals from port 0° and port 180° of the coupler and cable combination exhibits relatively large deviations from the ideal value of 180°.A vector network analyzer  was used to evaluate the S-parameters of the feed network and the antennas. The magnitude imbalance at the end of the cables was ≤0.5 dB within the 1.05 to 2.0 GHz bandwidth. After adding the phase trimmers, the differential phase error within 1.05 to 1.9 GHz bandwidth was A prototype of the differentially-fed, dual-polarized OCROP antenna, as shown in dd11 and Sdd22 are Y- and X-polarized differential reflection coefficients, respectively. As can be seen, there is good agreement between the simulated and measured results in terms of the operating frequency range where Sdd11 and Sdd22 ≤ −10 dB.To evaluate the differential reflection coefficients of the antenna, we conducted two types of measurements with a two-port VNA. The first type measured single-ended S-parameters at all antenna ports. The differential reflection coefficients were obtained from the post-processing of these data by assuming differential signals for one differential pair and matched loads for the other pair. In simulations, the reflection coefficients were calculated using the same post-processing approach  but with the single-ended S-parameters obtained numerically in HFSS. Both simulated and measured differential reflection coefficients using this method are shown in To provide differential feeding to the antenna, we used the feed network described in dd11 and Sdd22 would be slightly different if a different feeding network were to be used, and therefore, in practice, the feeding network must be carefully selected and designed.Radiation patterns were measured in a Compact Antenna Test Range. The simulated and measured results of the fabricated antenna are compared in In the measurement, there are two sources of errors for cross-polarization, i.e., the Compact Range reflector and the antenna mount. The Compact Range reflector is an offset reflector, and its cross-polarization is limited to −35 dB. The scattering from the antenna mount on the tower and the tower itself contributes to the cross-polarization. Despite the differences, the measured X-pols at 1.5 GHz still met the X-pol requirement of ≤ −25 dB in both principal and diagonal planes. In addition to the excellent electrical performance, the fabricated antenna is also lightweight (197.0 g) and compact (0.825 λ × 0.825 λ × 0.4 λ at the center frequency of 1.5 GHz).In this paper, the design procedure of a high-performance octagonal cavity-backed antenna was presented. The proposed antenna exhibits multiple attractive qualities: dual-polarization, wide impedance bandwidth, low cross-polarization, high gain, and high aperture efficiency. It can be used for many applications, such as remote sensing and satellite communication, where compact antennas with low cross-polarization are required. Alternatives are corrugated horns that are bulky, heavy, and very costly to fabricate. The cavity-backed configuration ensures that the antenna supports stable broadside radiation with relatively high gain and low cross-polarization. An octagonal ground cavity, instead of a more commonly seen square one, was used because it offers lower cross-polarization and higher aperture efficiency while being more compact. By merging the resonances from the open prism and the radiating feedlines, wide impedance bandwidth was realized. The bandwidth can reach over 60% by adjusting the air gap between the two radiators and the ground plane. Multiple design considerations were adopted to ensure low cross-polarization. Some basic ones include ensuring a symmetric antenna configuration, adopting a differential feed, and feeding the antenna from the ground sidewalls instead of the bottom ground plane. Further cross-polarization reduction can be realized by moderately increasing the cavity sidewall height. To verify the design and fabrication process, an antenna prototype was fabricated and tested with excellent agreement between the simulated and measured results. To demonstrate the superior performance of the proposed antenna, we compared it with three high-performance cavity-backed antennas with wide impedance bandwidth in It has shown that there is a small section of the operating band  that is not sensitive to the cross-polarization suppression techniques used here. We will propose an additional cross-polarization suppression technique to overcome this issue in the future. In addition, since some applications require higher gain than reported here, we will investigate different gain enhancement techniques that are compatible with our design.


We use high-resolution LiDAR topography to characterize landforms, satellite images to classify the vegetation into forest types, and in-situ produced cosmogenic 10Be in the quartz extracted from soils and stream sediments to document spatial variations in soil erosion. The data document a strong correlation between forest type and topographic position , and a correlation between topographic position and 10Be-derived erosion rates over 103−104 years. Erosion is faster in valleys, which are mostly covered by monocot Palm Forest, and slower on surrounding hills mostly covered by the dicot Palo Colorado Forest. Transition from one forest type to the next occurs across a break-in-slope that separates shallowly convex hilltops from deeply concave valleys (coves). The break-in-slope is the consequence of a longer-lasting erosional imbalance whereby coves erode faster than hills over landscape-shaping timescales. Such a deepening of the coves is usually spurred by external drivers, but such drivers are here absent. This implies that cove erosion is driven by a process originating within the coves themselves. We propose that vegetation is the primary driver of this imbalance, soil erosion being faster under Palm forest than under Palo Colorado forest. Concentration of the Palm forest in the deepening coves is reinforced by the better adaptation of Palm trees to the erosive processes that take place in the coves, once these develop steep slopes. At the current rate of landscape development, we find that the imbalance started within the past 0.1–1.5 My. The initiation of the process could correspond to time of settlement of these mountain slopes by the Palm and Palo Colorado forests.Topography is commonly viewed as a passive backdrop on which vegetation grows. Yet, in certain circumstances, a bidirectional feedback may develop between the control of topography and the spatial distribution of vegetation and landform development, because vegetation modulates the erosion of the land surface. Therefore, if reinforcing feedbacks are established between erosion and land cover distribution over timescales relevant to landform development, then the interactions between vegetation and topography may create distinctive landforms, shaped by vegetation. We expose here a strong correlation between the spatial distribution of vegetation, erosion rates, and topography at a characteristic length scale of 10 Here we document the distribution of landforms, vegetation, and erosion rates across the tropical montane forest of Luquillo, in Puerto Rico, over timescales relevant to landscape development.Topography affects the distribution of vegetation over a wide range of spatial scales. At the scale of mountain ranges  , albeit 10Be measurements in quartz collected in forest soils and river sands. The DEM and the satellite images are used to explore correlations between vegetation and topography. The 10Be data is combined to the DEM data to analyze the distribution of erosion rates across the topography over 103−104 years. The geomorphological analysis of the DEM is used to identify landforms produced by longer (104−106 years) imbalance in erosion across the landscape. The current imbalance in 10Be-derived erosion rates is used to calculate the time required to produce the current landscape over the timescale revealed by the DEM analysis. We then review the potential drivers of observed spatial variations in erosion rates. We propose that the variations are strongly influenced by the distribution of vegetation across the landscape.The study relies on three datasets: a high-resolution LiDAR digital elevation model (DEM), high-resolution satellite images, and in situ-produced cosmogenic 2 in the headwaters of Río Blanco, a river that drains the southern flank of the Luquillo Mountains in Puerto Rico (Prestoea Montana) forest and the Palo Colorado (Cyrilla Racemifolia) forest, which respectively cover 43% and 57% of the study area, located between 600 and 750 m.The study area covers 16.3 kmrto Rico . The Ríorto Rico . Forest rto Rico . In betw10Be method for quantifying erosion rates [The study area  featureson rates . The stoon rates ), the ston rates , 12, preAirborne LiDAR data were collected by the National Centre for Airborne Laser Mapping (NCALM) in May 2011 . Persist2 of forest located within the boundaries of the reliable LiDAR data [2 of the classified forest . However, the more thorough investigations conducted in the study area have shown that 10Be concentration there varies with sediment grain size [10Be concentrations into basin-wide erosion rates. Therefore, in order to capture the full range of apparent denudation rates introduced by this dependency, we measured the 10Be concentration in the finest and coarsest measurable sediment grain size fractions across 14 streams, wherever such fractions stood at least six phi units apart . They are systematically separated from surrounding coves by a break-in-slope, below which slopes reach values ≥ 30° . A marginally better fit (AIC = 207 vs. 186) is obtained with elevation when using a non-linear relationship, but given that the relationship between rainfall and elevation is linear in the Luquillo Mountains, the use of a complex fitting is not justified. A much stronger correlation is observed for parameters that contrast hilltops and coves, such as slope steepness (2 = 0.89), or the depth of sheltering behind hilltops (2 = 0.90). They highlight the propensity of the Palm forest to occupy coves, while the Palo Colorado forest covers hilltops.Several years of field work on the site, and inspection of satellite images revealed that the distribution of the two main forest types that occupy the study area is controlled by several factors, and among them, topography . In orde10Be and soil denudation. Secular equilibrium is indeed expected on low-slope, shallow-curvature hilltops where diffusive processes dominate. In the Luquillo Mountains, it has been shown that the prevailing diffusive processes are soil creep, tree throw, and bioturbation [10Be concentration with soil depth. The assumption can be tested by fitting theoretical profiles of soil age and erosion rate to the observed concentrations [-1,  if we suppress our added correction for the effect of quartz enrichment in the topsoil [The erosion of the topsoil on hilltops  overlap with the lower range of soil erosion rates measured in the broad hilltops (~10–80 m∙My-1), possibly reflecting a slight additional accumulation of 10Be in the particles between their exhumation on the ridgelines and their arrival into the streams, during the slow, diffusive transport of quartz grains along the broad hilltop slopes. Erosion rates are higher in cove-dominated catchments, up to values of ~140 m∙My-1, according to the coarse fraction, and of ~80 m∙My-1 according to the fine fraction. These new stream data are consistent with earlier measurements that targeted larger catchments in the study area  and fine (73 ± 40 m∙My-1) fractions respectively as the end-member minimum rate of cove erosion (because they incorporate a component of hilltop erosion), and the average of hilltop soil erosion rates (50 ± 14 m∙My-1), we find that coves erode between >1.5 ± 0.9 and >2.5 ± 1.1. times faster than the hilltop soils, according to the fine fraction and coarse fraction, respectively  compared to the coves (1.6 ± 0.2 MWH∙m-2), based on the ArcGIS solar insulation function. Insulation, in any case, probably does not affect the distribution of the Sierra Palm, which grows opportunistically from shaded under-canopy to fully exposed brakes [We interpret the correlation between topographic position (hilltop or cove) and forest type  as the result of a control of the distribution of vegetation by topography. This is a common observation, and in tropical areas, such a control exerts itself in a variety of ways that can act in concert , 3, 28. d brakes . The effd brakes , which ad brakes , 32. Pald brakes , whereasTopography further influences the distribution of forest types through the routing of surface and near-surface overland flow. Vegetation in the coves grows on steeper slopes (27±9°) than on hilltops 17±8°). Hilltops are therefore not as well drained as coves, and we observed that they commonly support water-logged hypoxic soils. Palm forest grows on well-drained steep terrain  but also±8°. HillTopography also influences the distribution of forest types through nutrient routing. In the study area, bedrock weathers to an intensely nutrient-depleted saprolite, and the weathering front lies far below the surface , 35. Thi10Be-derived erosion rates, but would need to exert itself over a period of time much longer than the integration time of the 10Be record. Assuming that the topographic envelope used to calculate the sheltering of the forest behind surrounding hilltop represents a first-order approximation of the initial topography from which the current topography has differentiated, and using the present-day differences in 10Be erosion rates between coves and hilltops . They also started the simulation from an initially flat landscape. They found that topographic differentiation would have started at 1.3 Ma. Suppressing our corrections for environmental parameters we find that, according to their calculations, differentiation would have started between 0.11 ± 0.7 Ma and 3.0 ± 2.7 Ma , floodplains would be lowering at <11-31m∙My-1, that is, much more slowly that cove erosion, and even more slowly than hilltop erosion. Besides, it is more likely that the bedrock below the floodplains rises in the upstream direction, and this effect should be even smaller. Last, the rate of floodplain lowering should be unsteady to trigger a drop in base level susceptible to initiate faster incision of the coves, and there is no evidence, for an acceleration of the knickpoints over the past millions of years [The decoupling between hilltops and coves pervades the entire study area and therefore implies that valley deepening is a response to an event affecting the entire area. Valley deepening is most commonly caused by accelerated lowering of the base level of the rivers that drain the valleys. Here, however, the base levels of coves are shallow-gradient alluviated floodplains  that do -1 . The upsof years . InsteadSome coves host seeps in their headwaters. Seepage may contribute to cove growth , by grou-1 [The study area erodes quite slowly  con-1 , and the-1 . The str-1 , owing t-1 , where p-1 . It appe-1 . Given t-1 , one can-1 . We obse-1 .We propose that, at the start of the process of topographic differentiation, Palm trees were slightly more abundant in the valleys, promoting faster erosion of the soil on slopes that were not initially distinctively steeper than on ridgetops . The proIf topographic differentiation is thus originally and primarily driven by topographically-controlled vegetation, then topographic differentiation can be expected to have started when the study area, currently located at elevations of 600–750 m, was settled by Palm and Palo Colorado forest. Our simple calculation, which assumes a linear development, suggests that such an event would have taken place between 0.11 ± 0.03 and 1.4 ± 0.3 Ma. This timing is consistent with the age of the Luquillo mountains, which started to rise < 4.5 My ago . Palm anAt the scale of the Luquillo Mountains as a whole, the preponderant role played by vegetation in landscape evolution is highlighted by the fact that the forest has protected the mountains from rapid hillslope erosion and stream incision, over the past millions of years . The forA strong correlation between topography and vegetation is observed at the scale of hilltops and valleys, within a slowly eroding part of the Luquillo Mountains. Hilltops tend to attract Palo Colorado forest, while the surrounding, deeply concave valleys (coves) tend to host Palm forest.Topography can control the distribution of these forest types in various ways. In landscapes strongly depleted in bedrock nutrients, such as here, fluxes of bedrock nutrients likely play a significant role in topographically-driven forest differentiation.10Be produced in quartz located in hilltop soils and stream sediments reveals that the coves are eroding faster than the hilltops, confirming, and expanding earlier observations.An inventory of the concentration of cosmogenic A systematic break-in-slope separates the shallow-dipping, low-curvature hilltops, from the surrounding, deeply concave coves. This topographic signature can be produced by perpetuation of the current imbalance in erosion between hilltops and coves over 0.1–1.5 My.We interpret the differences in erosion rates between hilltops and coves as driven initially by the difference in ground protection offered by sharp differences in subaerial and underground structure provided by the canopy-forming trees, their undercanopy, the litter, and the root mats between the two types of forests. Palo Colorado forest more efficiently suppresses soil saturation, slope wash, and landsliding than the Palm forest.Because these forest types are controlled by topography, a positive feedback exists that deepens the coves with respect to the hilltops over time, concentrates Palm forest in valleys and Palo Colorado forest on hilltops. The perpetuation of the process is ensured by the ability of the Palm forest to persist once the coves become steep, deeply confined between ridges, and struck by landslides.The initiation of the process may correspond to the time at which the study area was settled by the Palo Colorado and Palm forests. It also corresponds to the time at which local frog species, hosted by these forests, also started undergoing biodiversification.S1 File(PDF)Click here for additional data file.S2 File(PDF)Click here for additional data file.S3 File(PDF)Click here for additional data file.


Ventricular septal defect (VSD) is a catastrophic acute myocardial infarction (MI) complication. Despite a significant reduction in the prevalence of post-MI VSD with the advancement of surgical techniques, it is still considered fatal with a high mortality rate. The trends in the clinical outcomes of patients with post-MI VSD show discretion due to the complexity of the disease. Therefore, the present analysis aimed to evaluate the surgical outcomes and associated risks in the patients of post-MI VSD. A thorough literature survey resulted in 40 studies of our interest. The pooled proportion of differential variables, including the incidence of cardiogenic shock, 30-day survival, and overall mortality, were estimated using Bayesian hierarchical models. The risk difference was estimated for the location of MI and VSD and mortality in patients with coronary artery bypass graft (CABG). In addition, the heterogeneity tests for inconsistency and publication biases using Egger’s and Begg’s tests were also estimated. The analysis revealed a significant risk difference of 0.23 and 0.27 for the anterior vs. posterior location of MI and VSD, respectively. Further, the pooled proportion of 30-day survival and mortality was found to be 54.43% : 52.88-55.98%) and 48.22% (95% CI: 4-12.3%), respectively.an I2 index of >90% (p<0.0001). Lastly, the publication bias results suggested no evidence of asymmetry and small-study effects. Conclusively, the surgical management of post-MI VSD patients is considered beneficial; however, the outcomes signify its fatal behavior.Moreover, the heterogeneity test revealed significant inconsistencies in all the datasets with  Ventricular septal defect (VSD) or ventricular septal rupture (VSR) is a serious complication of acute myocardial infarction (MI) . During MethodsSearch ToolThe guidelines of the Cochrane Handbook and Meta-analysis of Observational Studies in Epidemiology , prepareData ExtractionThe following parameters were noted: age, gender, pre-procedures such as percutaneous coronary intervention (PCI), Qp: Qs and inotropes, ejection fraction and surgical procedures, timings of MI to VSD and VSD to repair in days, residual shunt and affected coronary artery. The analyzed parameters for the meta-analysis were: incidence of cardiogenic shock in PMI-VSD patients, anatomical location of MI, location of VSR, preoperative IABP and concomitant CABG, risk factors , 30-day survival, and overall mortality along with mortality associated with concomitant CABG, location of MI and location of VSR.Statistical AnalysisThe clinical and surgical outcomes data were retrieved from the selected publications or calculated after extracting the numeric data. Depending on the data, the pooled proportions of surgical outcomes and associated factors across studies were estimated from the exact number of patients with 95% credible intervals [CI] using the Bayesian hierarchical models or fixed-effects meta-regression of the natural logarithm of the risk difference was performed for comparative analysis. The results were depicted using forest plots. Further, heterogeneity tests for inconsistency (I2) levels and Egger’s and Begg’s tests for publication bias were performed across the selected publications. Publication bias is considered when deciding to publish a manuscript depending on statistically significant results. The statistical analysis was performed using MetaXL software.ResultsSearch ResultsDespite the declined incidence of post-MI VSD, the literature search resulted in 1795 articles; however, only 86 studies were identified as pertinent. Among the pertinent articles, 40 were considered for the final meta-analysis based on the data of interest  patients and posteriorly in 764 (46.17%) patients (28 studies). The analysis revealed a significant risk difference of 0.23 in the anterior vs. posterior location of MI . The I2 index was estimated to be 97.07% , which was significant. In addition, Egger’s  and Begg’s  tests showed non-significant results, stating no evidence of publication biases concerning the location of MI. The forest plot of risk difference estimation for the location of MI is given in Figure Further, 15 studies reported VSD localization in the anterior wall of 319 (54.43%) patients and the posterior wall of 267 (45.57%). The risk difference of anterior vs. posterior location of VSD was estimated to be 0.27, which was significant . The heterogeneity tests revealed a significant I2 index of 94.39% . In contrast, Egger’s  and Begg’s  tests revealed no publication biases in specifying the location of VSD in the patients. The forest plot of risk difference estimation for the location of VSD is given in Figure Associated Risk FactorsThe risk factors of coronary artery disease, such as smoking, dyslipidemia, smoking, and prior MI, were analyzed for their independent estimated proportions with respect to patients with post-MI VSD. Among 40 included studies, the data was mentioned in 15 studies for prior MI (161/1324 patients), 25 studies for diabetes 895/3527 patients), 27 studies for hypertension (2074/3571 patients), 21 for current smoking (667/2894 patients), and 11 for dyslipidemia (602/1840 patients). Figures  patients IABP, and Concomitant CABG in Post-MI VSD SubjectsIncidence of Cardiogenic Shock, PreoperativeAmong 40 chosen studies with 4,028 patients, 22 studies with 3,234 patients, 30 studies with 3349 patients, and 21 studies with 3286 patients provided the data of cardiogenic shock, preoperative IABP, and concomitant CABG in Post-MI VSR subjects, respectively. The analysis revealed that the incidence of cardiogenic shock and preoperative IABP were observed in more than half of the post-MI VSR population with estimated pooled proportions of 50.19% (95% CI: 48.46-51.92%) and 66.99% (95% CI:65.37-68.57%) respectively. On the contrary, the pooled proportion of concomitant CABG was 42.23% (95% CI = 33.95 - 49.23). The forest plots of the respective variables are provided in Figures Mortality as a Major OutcomeAll the 40 included studies provided the data of 30-day survival and overall mortality associated with post-MI VSD, which was found to be 2182/3996 and 1910/3996 with their estimated pooled proportions of 54.43% (95% CI: 52.88-55.98%) and 48.22% (95% CI: 4-12.3%)respectively, as shown in Figure Furthermore, the mortality concerning the location of VSR and concomitant CABG was corroborated in five studies with 252 patients and 12 studies with 1129 patients, respectively. The risk difference in mortality concerning the location of VSR and concomitant CABG was found to be -0.039 (95% CI = -0.169-0.091) and 0.068 (95% CI = 0.031-0.11) with their significant I2index of 96.88 %  and 96.86 % . Lastly, the publication bias using Egger’s and Begg’s tests suggested no evidence of asymmetry and small-study effects for all the analyzed variables in post-MI VSD patients across selected studies. The forest plots for mortality concerning the location of VSR and concomitant CABG are shown in Figures DiscussionPost-MI VSR poses a major clinical challenge due to high mortality -3. SeverIn the era of surgical interventions in patients with post-MI VSD, the incidence of post-MI VSD has significantly been reduced . EvidencIn most cases, delay in the surgical intervention occurs because surgeons wait for the formation and improvement of tissue scars -20. EarlAccumulating evidence in the literature suggests the association of various risk factors of coronary artery disease, such as smoking, dyslipidemia, smoking, and prior MI, with the development of post-MI VSD -6. The pThe localization of MI or VSR may be other considerable variables to elude worse outcomes. In the present data, we observed that the number of patients with anterior localization of disease was significantly higher than those with posterior wall or septum defects, signifying that the anterior wall or septum is more vulnerable than the posterior wall for both MI and VSR. Moreover, the risk difference in anterior vs. posterior location of both MI and VSR was found to be statistically significant. Furthermore, the mortality concerning the location of VSR was also assessed, and the risk difference in mortality with anterior or posterior localization of VSR was found to be statistically non-significant. The postoperative course is stormier in posterior VSR due to associated right ventricular dysfunction. The data suggest that the location of the defect did not influence the survival rate of patients with anterior or posterior defects. However, only 5 studies with 252 patients corroborated this data -30. MoreFurthermore, multi-vessel coronary artery disease patients underwent CABG during VSD repair -35. SubsLimitationsThe study has a few limitations. Firstly, the identified studies lacked information on the intervention techniques for the surgical management of patients with post-MI VSD, which is a major drawback. Secondly, no sufficient data was given on the interval between VSD diagnosis to repair and the location of MI in association with mortality.The present systematic review and meta-analysis evaluated the surgical outcomes and associated risks in the patients of post-MI VSD. A statistically significant risk difference was noted in the patients' anterior vs. posterior locations of MI and VSD. The 30-day survival rate remained low, while the mortality rate was higher even after better surgical interventions for the management of post-MI VSD. Our data suggest that concomitant CABG is an additional factor corroborating to mortality. We conclude that time from VSR diagnoses to repair should be considered for the timely management of patients with post-MI VSD that may provide better survival benefits.


Crohn’s disease (CD) is a subtype of inflammatory bowel disease (IBD). CD is a health problem in Western countries such as the US and European nations and is an idiopathic disease; however, certain cases of CD have been associated with intestinal dysbiosis. A systematic review with a meta-analysis was carried out to determine the efficacy of a diet rich in fiber with or without cointervention to improve remission rates for CD. The literature in the PubMed, Scopus, Web of Science, and ClinicalTrials databases was reviewed. The quality of the studies was evaluated using the Johanna Briggs Institute (JBI) scale. This review was conducted in accordance with the structure outlined in the PRISMA statement. In addition, a meta-analysis was performed with a 95% confidence interval (CI) and a random effects model. Eleven studies were included, totaling 2389 patients with CD. Applying a diet rich in fiber with or without the administration of routine therapies improved CD remission rates. Data regarding CD activity, remission time, and adverse effects derived from fiber consumption were analyzed. Consumption of fiber in the diet could improve remission rates for CD patients who receive or do not receive other treatment to maintain remission. Inflammatory bowel diseases (IBDs) are idiopathic pathologies, among which there are three subtypes: Crohn’s disease (CD), ulcerative colitis (UC), and unclassified IBD (IBD-U), the latter being the least frequent, accounting for 4% of IBD cases in Western countries . SpecifiIn patients with IBD, quality of life is highly compromised compared with that in individuals who do not suffer from gastrointestinal diseases . The sigDespite being a set of idiopathic diseases, several factors that promote the appearance of IBDs have been detected, including the following examples: (1) genetic factors ; (2) environmental factors related to developed countries ; and (3) immune system issues, which include decreased intestinal mucus, the infiltration of T and B lymphocytes, and the overproduction of inflammatory mediators such as TNFα, IFNγ, IL-1β, and IL-23, which in turn lead to abnormalities in the action of white cells such as macrophages, neutrophils, and NK T lymphocytes .Faecalibacterium prausnitzii (F. prausnitzii), Clostridium leptum (C. leptum), and Bacteroides have anti-inflammatory capacities at the intestinal level through the production of short-chain fatty acids (SCFAs), and these species are diminished in patients with IBDs [E. coli and Fusobacterium are more abundant [Another factor to consider in order to understand the pathogenesis of IBDs is the intestinal microbiota. Specifically, compared with individuals without IBD, those with IBD have imbalances in different commensal species at the intestinal level; this phenomenon is known as dysbiosis . In geneith IBDs . In contabundant .SCFAs are anti-inflammatory substances that are produced by the degradation of soluble fiber at the intestinal level by the aforementioned microbiota species . Some exAmong IBDs, CD is the most common. To control the symptoms of CD, there are multiple therapeutic options, of which those whose objective is to regulate intestinal inflammation by directly affecting the functioning of the immune system stand out . There aTo date, how the consumption of foods rich in fiber can exert beneficial effects on individuals with CD has been studied on other occasions; for example, a Cochrane review carried out in 2019 included 18 studies on dietary interventions for CD. However, not all the studies included in the review analyzed fiber consumption ,22.The objective of this study was to synthesize the scientific evidence available to date of a diet rich in fiber as a method to prevent acute flare-ups of CD as well as to analyze the effects regarding positive clinical improvements.This systematic review was carried out in accordance with the standards outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement . The detThe following databases were searched: PubMed, Scopus, Web of Science, and ClinicalTrials.The searches were conducted to answer the research question directly, which was developed in the population, intervention, comparison, and outcome (PICO) format . The seaComponents of the PICO research question are as follows: P: problem; I: intervention to be analyzed; C: comparison or control; and O: outcomes.The clinical question was as follows: in the population with CD, does an adequate consumption of fiber in the diet provide greater benefits than conventional therapies and normal diets to prevent CD recurrence and improve CD symptoms?The detailed search strategies for each database are listed in Observational studies;Clinical trials;Studies that analyzed the consumption of a diet rich in fiber to maintain CD remission;Studies in Spanish or English.The inclusion criteria used to select the studies that are part of this review were as follows:Studies that were conducted with animals;Studies that did not include patients with CD in their study population.The following types of studies were excluded:Study selection was carried out by two researchers, V.S.F. and M.S.P., using the inclusion and exclusion criteria mentioned above. The searches yielded 677 results (the Mendeley computer program was used to avoid duplicates); the selection process followed the flow chart detailed in the PRISMA statement . Once duTo assess the quality of the studies and detect biases, Johanna Briggs Institute (JBI) scales were used  for eachThe quality assessment was independently reviewed by two authors: V.S.F. and M.S.P. The interrater reliability was high, and any discrepancies were discussed between J-M.C.T. and J-A.L.A. until an agreement was reached.Data extraction was carried out by two researchers: V.S.F. and D-P.P.C. From each selected study, the following data were collected: (1) title and authors; (2) year and country; (3) study design; (4) sample characteristics: sample size, selection, and age of participants; (5) study objective; and (6) main results: type of fiber consumption and clinical remission rate.When interpreting the information found, the diet was considered effective when it contributed to maintaining the clinical remission of CD alone or in conjunction with other therapeutic strategies, and the intervention was considered safe as long as it did not produce adverse effects that were different from those produced by conventional therapies.For the studies selected for this review, a narrative synthesis was performed. The data were analyzed to compare results between patients who consumed a diet rich in fiber and patients who received the usual treatments or consumed common diets. Additionally, complications derived from consuming diets rich in fiber were recorded.2 statistic. I2 ≤ 25%, I2 between 26 and 50%, and I2 > 50% were used to define low, moderate, and statistically significant homogeneity, respectively [For the quantitative analysis, a meta-analysis was performed using the inverse variance method of random effects. The standard deviations (SDs) of the pre- and postparameters (high fiber diet + infliximab versus control) of each study were calculated. Statistical heterogeneity was evaluated with the IThe searches of the four databases yielded a total of 677 results. The Mendeley computer tool was used to eliminate duplicates and manage the references. After eliminating duplicates, a total of 659 results remained.Following the criteria established, 515 results were excluded. Eleven studies met the aforementioned inclusion criteria ,32,33,34All the selected studies were written in English and were either RCTs or observational studies that investigated diets rich in fiber and from which conclusions could be drawn regarding the maintenance of clinical remission in patients with CD. The characteristics of the included studies are presented in Of the 11 studies selected, 2 were RCTs ,34, 3 weThe selected studies included a total population of 5010 subjects, of whom 44% were men and 56% were women. This population ranged in age from 13 to 77 years.In the studies, there were 2389 patients with CD, and the remaining participants were patients with UC or healthy subjects. The sample included patients with all types of CD based on the Montreal classification  .Two of the eleven studies selected compared these types of diets. In general, the high-fiber diet was safer than the gluten-free diet . AdditioSpecifically, the study carried out by Schreiner P, et al.  comparedThe study carried out by Heaton K, et al.  comparedOf all the selected studies, six assessed the consumption of certain foods together with the risk of relapse or CD activity, of which five showed positive results from consuming a diet rich in fiber ,28,33,34The study published by Tasson, L, et al.  assessedThe study carried out by Dolovich C, et al.  evaluateAnother study by Mirmiran P, et al.  assessedThe study carried out by Opstelten J et al.  investigHowever, the study carried out by Brotherton C, et al.  yielded Finally, the trial carried out by Lacerda J et al.  analyzedDue to the heterogeneity of the outcome variables in these studies, it was not possible to carry out a quantitative analysis  of the benefits of a high-fiber diet alone.Three studies analyzed how the consumption of a diet rich in fiber influenced patients receiving infliximab as background therapy ,30,31. TA study conducted by Chiba M et al.  observedIn another study by the same author , 17 of tThe third study carried out by Chiba M et al.  investigp = 0.08; I2 = 0%).The results of the meta-analysis  showed aOf all the selected studies, only three showed any adverse effects. Two patients in the study by Chiba M et al.  had inteNotably, another study  reportedHowever, in the remaining studies analyzed ,31,33,34Based on the results obtained, high fiber intake through the diet is not only safe but also effective in maintaining remission in conjunction with other therapies for patients with CD.From a nutritional point of view, certain habits increase the risk of IBD flare-ups; for example, consuming red meat more than four times a week increases the risk of UC flare-ups . In the Although the efficacy of fiber in maintaining CD remission cannot be denied ,28,31,32By professional consensus, the consumption of fiber is recommended to all patients with IBD, as long as they do not have intestinal stenosis; insoluble fiber could act at the level of the intestinal lumen, producing an increase in fecal waste and increasing the risk of occlusive symptoms at the intestinal level ,40. LikeA Cochrane review reported how a diet rich in fiber produces an increase in SCFAs, promoting intestinal homeostasis and helping to control inflammation in patients with CD , as specThe consumption of dietary fiber by patients with CD was lower than that by healthy controls (4 g/day difference between groups), with a total fiber consumption of 14 g/day in patients with CD . HoweverFiber administered at controlled doses and in the form of a supplement is effective in controlling the symptoms of CD ,45. SpecTo clarify more accurately whether a nutritional intervention rich in fiber is adequate to maintain remission in patients, more RCTs are needed that compare control groups with conventional therapy groups and experimental groups and that specify the diet administered to the patients as well as the amount of fiber needed. Furthermore, such studies should be conducted for a sufficient time to ensure the reliability of the results obtained. Only two studies evaluated interventions long enough to identify the remission rates for patients clearly; the evaluation time was greater than 2 years ,31.Among the studies included in the analysis in this review ,30,31 arAmong the limitations of this review are the small number of RCTs included in the review and the lack of nutritional specifications of the diets used or investigated in the studies. In the studies included in this review, the type of fiber consumed by the subjects was not accounted for except in one study, which included soluble fiber in the participant diet . This maAnother limitation was the heterogeneity in the variables resulting from the included studies; this heterogeneity made it impossible to carry out the meta-analysis. In fact, in the meta-analysis conducted, diet interventions were different among selected studies , so it is difficult to compare them. Also, it is important to mention that these studies were low quality, and only two RCTs had a control group ,34.Furthermore, one study did not use analytical, or endoscopic criteria to measure CD activity . It is nAs strengths, the sample size in each study was sufficient to clearly reach the conclusions obtained. The studies were carried out in different parts of the world; therefore, information was collected from different populations.It seems that high dietary fiber intake can increase the remission time in patients with CD. It is a simple nutritional practice without risk for patients. However, adjuvant treatment with a diet rich in fiber should be supervised by a health professional because one of the functions of health personnel is to provide health education. Under these conditions, the consumption of a high-fiber diet is recommended.Dietary fiber intake could increase remission rates in patients with CD who achieve clinical remission with conventional therapies. Due to scarce evidence about the relationship between fiber intake and CD, we cannot recommend a specific dietary intervention. However, it can be stated that a fiber intake between 13.4 and 33.4 g/day is safe in CD patients. Also, a high-fiber diet should be an adjuvant treatment in conjunction with other therapeutic strategies to maintain remission.More studies are needed to evaluate the amount and type of fiber to improve remission rates for CD. Specifically, we believe it is necessary to conduct more RCTs that analyze conventional therapies and high-fiber diets in combination with conventional therapies, with analytical and endoscopic follow-up to determine the efficacy of the intervention.


Additionally, leveraging data from the genome-wide association study (GWAS) catalog, we discovered >1.3 million paQTLs that overlap with known GWAS linkage disequilibrium regions. Remarkably, ∼9324 paQTLs exhibited significant associations with patient prognosis. Moreover, investigating the impact of promoter activity on >1000 imputed antitumor therapy responses among pan-cancer patients revealed >43 000 million significant associations. Furthermore, ∼25 000 significant associations were identified between promoter activity and immune cell abundance. Finally, a user-friendly data portal, Pancan-paQTL (https://www.hbpding.com/PancanPaQTL/), was constructed for users to browse, search and download data of interest. Pancan-paQTL serves as a comprehensive multidimensional database, enabling functional and clinical investigations into genetic variants associated with promoter activity, drug responses and immune infiltration across multiple cancer types.Altered promoter activity has been generally observed in diverse biological processes, including tumorigenesis. Accumulating evidence suggests that employing a quantitative trait locus mapping approach is effective in comprehending the genetic basis of promoter activity. By utilizing genotype data from The Cancer Genome Atlas and calculating corresponding promoter activity values using   Located upstream of transcription start sites, promoter elements play a crucial role in regulating the initiation and activity of transcription. They integrate signals from proximal epigenetic modifications and distal regulatory elements. In humans, the transcriptional initiation of most protein-coding genes is controlled by multiple promoters, leading to the production of distinct gene isoforms ,2. Unlikcis-regulatory mechanism of promoter activity has been studied in both cancer and normal human tissues. For example, an intergenic variant, rs8028374 (A/G), was identified as a paQTL associated with the outermost promoters of the TTC23 gene in Epstein–Barr virus-transformed lymphoblastoid cell lines  (Single nucleotide polymorphisms (SNPs), the most common type of genetic variant, contribute to the diversity in human disease susceptibility . Genome-ll lines . Epigenoll lines . In addill lines . In spits (TCGA) . This mahttps://www.hbpding.com/PancanPaQTL/), to provide convenient browsing, searching and downloading of paQTL-related data of interest for users.To fill this gap, we developed a computational pipeline to conduct paQTL analysis across 33 cancer types in TCGA. Our study identified paQTLs associated with patient prognosis and paQTLs within linkage disequilibrium (LD) regions of GWAS. In addition, we investigated the paQTL–drug associations and paQTL–immune cell associations across different cancers. Finally, we constructed a user-friendly database, Pancan-paQTL . Promoter activity, defined as the total amount of transcription initiated at each promoter, was estimated using proActiv with aligned reads as input (https://github.com/GoekeLab/proActiv). We specifically employed the promoter activity associated with the primary or default promoter of genes with multiple alternative promoters. Distribution of absolute promoter activity across cancer types is displayed in TIMER, MCP-counter and ImmuCellAI (https://www.cancerrxgene.org/) drug response from cancer cell lines to TCGA patient samples was estimated using oncoPredict R package  and junction files (level 2) quantified by STAR of >10 000 tumor samples were downloaded from the TCGA data portal , patient age and gender, and tumor grade and stage regarded as confounder factors were also estimated to decrease potential impacts from population structure, batch effect and clinical characteristics for each tumor type. The promoter activity matrix, genotype and covariates were then used to detect paQTLs based on a linear regression model by Matrix eQTL. We defined SNPs with false discovery rates (FDRs) <0.05 as paQTLs. cis-paQTLs were ascertained when the SNP was located within 1 Mb from the specific promoter, and trans-paQTLs were identified when the SNP was beyond that location. On the basis of tag SNPs derived from the GWAS Catalog website (http://www.ebi.ac.uk/gwas/) and the LD calculated by PLINK in the 1000 Genomes Phase 3 European population, cis- or trans-paQTLs that were in LD relation (r2 > 0.5) with tag SNPs were defined as GWAS-paQTLs. Both cis- and trans-paQTLs were retrieved to investigate their potentially prognostic value by a log-rank test, with FDR < 0.05 regarded as statistical significance  was used to impute genetic variants of TCGA tumor samples with the reference panel of the 1000 Genomes Project. The imputation parameters including minor allele frequency >5%, missing rate of SNPs <5% and Hardy–Weinberg equilibrium ificance .oncoPredict was used to predict in vivo drug responses in cancer patients on the basis of linear ridge regression analysis, which fits the gene expression matrix of samples into the half-maximal inhibitory concentration of antitumor drugs originated from GDSC (https://www.cancerrxgene.org/). Then, the associations between promoter activity of each cis- or trans-paQTL and imputed drug response were investigated by Spearman’s correlation analysis with FDR < 0.05 regarded as statistical significance .All data are available through our data portal  and tumor signaling pathways (e.g. NF-κB and STING), indicating that paQTLs might impact patient prognosis by regulating promoter activity of cancer-related genes or cancer-related pathways. Number of paQTL pairs is significantly associated with the number of patient samples across cancers , most trans-paQTL pairs were identified in adrenocortical carcinoma  and most survival-associated paQTL pairs were detected in cholangiocarcinoma (n = 981) (r2 ≥ 0.5) of one or multiple human traits, of which the highest is 187 257 in pancreatic adenocarcinoma and the lowest is 22 441 in breast invasive carcinoma (Distance between QTLs and promoters <1 Mb is regarded as n = 981) . In addiarcinoma .in vitro cell models. In total, 43 225 correlations between promoter activity and impute drug responses were identified in our analysis (Figure In anticancer drug response analysis, we calculated the correlations between promoter activity and imputed drug response across 33 TCGA cancer types, which offer much more direct and significant effect of promoter activity in anticancer therapy than s Figure .TIMER, 7891 associations from ImmuCellAI and 14055 associations based on MCP-counter (Figure http://www.hbpding.com/PancanPaQTL/download.Current studies have demonstrated the important function of promoter activity in modulating the infiltration of immune cells and the efficiency of checkpoints. The correlations between promoter activity and the infiltration of immune cells were also investigated in our analysis, which provides potential paQTL-based biomarkers for tumor immunotherapy. We identified 24 935 correlations between promoter activity and the infiltration of immune cells, including 2989 correlations from r Figure . All abot-stat value, P-value and FDR of paQTLs (Figure P-value and median prognostic time of different genotypes. For each query, a vector diagram of the Kaplan–Meier plot was offered for illustrating the correlation between SNP genotypes and prognosis (Figure R2 and the associated traits (Figure cis-paQTL pairs, 33 GWAS-paQTL pairs, 14 drug–paQTL pairs, 20 immune-associated paQTL pairs and related diagrams (cis-paQTL pair, one GWAS-paQTL pair, one drug–paQTL pair, one immune-associated paQTL pair and related diagrams (Pancan-paQTL has six modules: Cis-paQTL, Trans-paQTL, Survival-paQTL, GWAS-paQTL, Drug-paQTL and Immune-paQTL Figure . On the s Figure . For eacs Figure . On the s Figure . The Drus Figure . The Imms Figure . For exadiagrams . While tdiagrams .The outputs from all analyses, including tables and high-resolution figures, can be easily downloaded from the Pancan-paQTL database. The ‘Help’ page provides the basic information on database, pipeline of database construction, result summary and contact. Pancan-paQTL is open to any feedback with email address provided at the top of the ‘Home page’.Alternative promoters play a crucial role in regulating transcription and have been found to be more accurate predictors of patient survival than gene expression in cancer . UnderstTo address these gaps, our analysis comprehensively integrated promoter activity with genetic variants, anticancer drug response and immune cell infiltration across human cancers, resulting in the identification of millions of promoter activity associations. To facilitate access to this valuable information, we developed the user-friendly Pancan-paQTL database, which allows users to query, browse and download promoter activity-correlated genetic variants, anticancer drug response and immune infiltration landscapes across multiple cancer types. The complex nature of gene modulation and the challenge of linking genetic variants to phenotypes necessitate further exploration. Within Pancan-paQTL, we identified >1 million paQTLs and evaluated their correlations with patient prognosis, offering a valuable resource for investigating human tumor genetics. This includes uncovering novel mediation mechanisms between variants and promoter activity to better understand the impact of variants on phenotypes, as well as shedding light on the role of genetic variants in promoter activity and their underlying functions in tumor prognosis and diagnosis.oncoPredict method to estimate drug response in cancer patients, leading to the identification of numerous paQTL–drug correlations between paQTLs and imputed drug response across 33 cancer types. It is important to note that the TCGA data resource is useful for characterizing initial cohorts, but it may differ from the patient population in clinical trials, which often consists of heavily pretreated individuals with distinct molecular features.Increasing evidence indicated that promoter activity, or active promoters, may affect the response to anticancer therapy. However, the associations between drug response and promoter activity in a large number of cancer samples have not been extensively investigated. Estimating drug response in cancer patients can provide a more direct and significant measure for antitumor treatment. In our analysis, we utilized the Immunotherapy has demonstrated significant clinical benefits in various cancer types, and efforts are ongoing to enhance its effectiveness by understanding the tumor immune microenvironment and the underlying mechanisms of checkpoints ,22. ReceIn conclusion, Pancan-paQTL is a large-scale and multidimensional database that facilitates functional and clinical explorations of promoter activity across human cancers. We will continue to update Pancan-paQTL with the release of additional associated datasets, ensuring its relevance and usefulness for future research endeavors.zcad053_Supplemental_FilesClick here for additional data file.


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