Miracle-dz/UniFAR-FTUs huggingface dataset:
The effects of electrostatic interaction between biological molecules and nano-metal colloid on near-infrared surface-enhanced Raman scattering

This paper reports effects of electrostatic interaction between amino acid and gold colloid on the intensity of surface-enhanced Raman scattering (SERS). Near-infrared (NIR) excited SERS has been measured for lysine (Lys) on gold colloid at pH 10.8 and 12.0 where its ε-amino group is ionized and both the α- and ε-amino groups are neutralized, respectively. Note that the SERS intensity changes dramatically with pH. This result suggests that the electrostatic interaction between the positive charge of the ε-NH3+ group and the negative charge of the gold surface is one of the most important factors that determine the intensities of the SERS signals. A similar SERS study has been carried out for glycine (Gly) on gold colloid at various pH values. It also suggests that the positively charged amino groups interact with the negatively charged gold surface, yielding a SERS effect. The chemical interactions are much less important for the emergence of SERS of Gly on the gold colloid.
Compact filtering magic‐T using a hybrid microstrip‐cavity structure

This letter introduces a filtering magic‐T based on a hybrid microstrip‐cavity structure. TE011 and TE101 modes of the cavity are generated by the two perpendicular input microstrip lines to form the filtering responses. Because of the orthogonality of the feeding lines and the two resonant modes, in‐ and out‐of‐phase output currents and high port isolations are achieved. The measured filtering responses of the two input ports are in good agreement with each other and possess high‐frequency selectivity. The isolations of the input and output ports are below 41 and 22 dB, respectively. Moreover, benefiting from the hybrid microstrip‐cavity structure, only two cavity resonators are employed, which realizes compact size.
Design and development of an economical temperature compensated bidirectional fiber Bragg grating flow sensor

A target-type cantilever based temperature compensated fiber Bragg grating (FBG) flow sensor is designed and developed with economical demodulation and data acquisition schemes. FBG is glued on the surface of a thin elastic stainless steel cantilever in pre-strained condition. The cantilever is mounted inside a flow channel by a special purpose brass holder with a height and direction adjustable threaded stem. The sensor is interrogated by an optical spectrum analyzer (OSA) and indigenously developed twin FBGs and chirped FBG—FBG intensity demodulation schemes. Response of the sensor is investigated in the flow rate range of 0–10 l min−1 in both forward and reverse flow directions. In spectral demodulation, the flow sensor offered a linear response in the full investigated range with a sensitivity of 19.2 pm/(L/min). However, the twin FBGs demodulation scheme presented a linear behaviour in the range of 4–10 l min−1 with sensitivities of 1.22 ± 0.03 μW/(L/min) and 29.89 ± 0.55 mV/(L/min) detected by the high speed power meter and photodetector, respectively. The novel CFBG-FBG intensity demodulator offered a linear response throughout its tested range and can offer a flow rate detection up to 265 l min−1 at the present sensitivity of the sensor with the condition that the cantilever-FBG system must be strong enough to withstand the higher flow rates. The temperature of the fluid is monitored by an FBG temperature sensing probe connected to the flow channel using intensity demodulation scheme by another pair of twin FBGs. Temperature compensation of the flow sensor is performed by arithmetic operations over the reflection intensities due to temperature probe to the results of the flow rates using a cost-effective data acquisition scheme.
Subset Basis Approximation of Kernel Principal Component Analysis

Principal component analysis (PCA) has been extended to various ways because of its simple definition. Especially, non-linear generalizations of PCA have been proposed and used in various areas. Non-linear generalizations of PCA, such as principal curves (Hastie & Stuetzle, 1989) and manifolds (Gorban et al., 2008), have intuitive explanations and formulations comparing to the other non-linear dimensional techniques such as ISOMAP (Tenenbaum et al., 2000) and Locally-linear embedding (LLE) (Roweis & Saul, 2000).
Observations with a VLB array. II - The sources 4C 39.25, NRAO 150, VRO 42.22.01, 3C 345, and 3C 454.3

Three-antenna long-baseline interferometry at 10.7 GHz is reported for NRAO 150, 4C 39.25, 3C 345, VRO 42.22. 01, and 3C 454.3 for several epochs between 1972 April and 1974 February. Simple models for the source brightness distributions fit the observations and indicate that most of the radio emission comes from one or two components. Component separations range up to approx.50 lt-yr, and component sizes are on the order of 10 lt-yr. Small variations in source structure have been observed.
Investigation of an efficient short-scan C-arm reconstruction method with radon-based redundancy handling

The short-scan Feldkamp David Kress (FDK) method for C-arm CT reconstruction involves a heuristic raybased weighting scheme to handle data redundancies. This scheme is known to be approximate under general circumstances and it often creates low frequency image artifacts in regions away from the central axial plane. Alternative algorithms, such as the one proposed by Defrise and Clack (DC),1 can handle data redundancy in a theoretically exact manner and thus notably improve image quality. The DC algorithm, however, is computationally more complex than FDK, as it requires a shift-variant 2D filtering of the data instead of a efficient 1D filtering. In this paper, a modification of the original DC algorithm is investigated, which applies the efficient FDK filtering scheme whereever possible and the DC filtering scheme only where it is required. This modification leads to a more efficient implementation of the DC algorithm, in which filtering effort can be reduced by up to about 70%, dependent on the specific geometry set-up. This gain in computation speed makes the DC method even more attractive for use in an interventional environment, where fast and interactive X-ray imaging is a crucial requirement.
Dependency-Based Syntactic Analysis of Bulgarian

The interest in dependency grammar has clearly been on the rise in the last 10– 15 years. The parsing community has seen a number of benefits in the use of and parsing with dependency-based representations of syntactic phenomena. On the one hand, dependency trees are much simpler than phrase-structure trees – they contain exactly the same number of nodes as there are tokens in the sentence. The words in the sentence are linked by binary, asymmetric relations, the so called dependencies. In addition, every link is often labelled with the syntactic or semantic relation which holds between the two words. A tree labelled with such relations encodes the predicate-argument structure of a clause in a much straightforward way than phrase-structure trees. Finally, a number of parsing algorithms have been proposed whose running time is linear with respect to the number of tokens in a sentence. The availability of syntactically annotated corpora has facilitated the use of supervised machine learning methods in the field of parsing. Data-driven parsers, which rely on corpora for the training stage can be acquired for any language for which such an annotated corpus exists. In addition, they are robust and efficient for the given task. Therefore in the present work we have used data-driven parsing with syntactic dependency representations for Bulgarian. This thesis deals with three topics, with each part building on the findings of the previous one. First, we have chosen to adopt the framework of dependency grammar and apply it to syntactic phenomena in Bulgarian. We have identified dependency structures and relations which cover a number of phenomena in the language. However, the central issue is the proper encoding of the predicateargument structure within the chosen framework. No other studies of Bulgarian have dealt with this issue from a dependency grammar point of view. Secondly, once the crucial structures and relations have been identified, we have used those priciniples in the conversion of a constituency-based treebank of Bulgarian. Again we argue for the need of the proper transfer of the predicateargument structure from a constituent tree into the dependency graph. This need reflects the nature of the underlying structures in the original treebank, where complex verb-phrases have a flat annotation. In addition, the principles we adopt lead to increase of non-projective structures compared to previous conversions of the treebank. Finally, the performance of two data-driven parsers have been tested on the acquired treebank. The aim is not only to achieve state-of-the-art results for parsing Bulgarian, but what is more important – to test the performance with respect to a higher number of non-projective structures and a verb argument structure which is more complex than previously created.
High sensitivity of p-modes near the acoustic cutoff frequency to solar model parameters

The p-mode frequencies of low l have been calculated for solar models with initial helium mass fraction varying from Y = 0.2753-0.2875. The differences in frequency of the p-modes in the frequency range, 2500-4500 microHz, do not exceed 1-5 microHz among the models. But in the vicinity of the acoustic cutoff frequency, near 5000 microHz the p-mode frequency differences are enhanced by a factor of 4. The enhanced sensitivity of p-modes near the acoustic cutoff frequency was further tested by calculating and comparing p-mode frequencies of low l for two solar models one incorporating the Eddington T-tau relation and the other the Krishna Swamy T-tau relation. Again, it is found that p-modes with frequencies near the acoustic cutoff frequency show a significant increase in sensitivity to the different T-tau relations, compared to lower frequency p-modes. It is noted that frequencies above the acoustic cutoff frequency are complex, hence, cannot be modeled by the adiabatic pulsation code (assumes real eigenfrequencies) used in these calculations. 20 refs.
Toroidal moments in the physics of electromagnetic and weak interactions

The analytic structure and geometrical meaning of multipole expansions for systems containing convection and induction currents are illustrated in the framework of classical electrodynamics. The main attention is devoted to the expansion of the transverse electric part of the current, in which the authors have identified a third family of multipole parameters: toroidal moments and their radii. The electromagnetic properties of the simplest toroidal systems are analyzed. The connection between multipole expansions and the methods of invariant parametrizations of relativistic matrix elements of a current operator is emphasized. Some consequences and effects of the existence of these moments are pointed out in the theory of atomic and nuclear transitions. A review is made of the results achieved on the extraction of toroidal moments of nuclear transitions through nuclear conversion penetration parameters, the possibilities of extracting information about toroidal giant resonances, etc. The results are given of the study of anapoles (toroidal dipoles) in the framework of the problem of parity violation by the electroweak interactions in atomic, nuclear, quasinuclear, and quark systems.
A first principles theoretical examination of graphene-based field effect transistors

This paper presents an in-depth theoretical examination of graphene-based field effect transistors, looking at thermal statistics, electrostatics, and electrodynamics. Using a first principles approach, the unique behavior observed in graphene-based field effect transistors, such as the V-shaped transfer characteristic, limited channel pinch-off, and lack of off-state (under gate modulation), are described. Unlike previous attempts, a description of both drift and diffusion currents in the device is presented. The effect of external resistance on steady-state and high-frequency performance is examined. Comparisons of the theoretical results to experimental results are made and show good agreement. Finally, the theoretical work in this paper is used as a basis to discuss the possible source of some observed behavior in practical graphene-based field effect transistors.
The study of magnetic activity and exoplanet magnetospheres using EChO VNIR-channel spectropolarimetry

The EChO satellite provides an opportunity to investigate the magnetic stellar activity and the nature of magnetic interactions of exoplanets with their host stars by using spectropolarimetry from space. These include auroral phenomena induced by the coupling on the exoplanet, induced flows between the planet and parent star, and a broad range of signatures of enhanced magneto-hydrodynamic interactions. A comprehensive view of the structure and evolution of exoplanetary atmospheres requires investigating the escape mechanisms of their constituent species, including the effect of a planetary magnetosphere. Given the distribution of masses and orbital parameters among the currently known gas giant exoplanets, the presence of a significant magnetic field could have some surprising consequences. In analogy with active dynamo-generated fields in close binary star systems, such as the RS CVn stars, a planetary field could link to that of the parent star, producing a strongly dissipative torque and magnetically and tidally locking the planet to its central star. Additionally, the study of stellar magnetism aids understanding of the coronal and chromospheric activity that affects the evolution of the planetary atmospheres.
Partitions of combinatorial structures

In this thesis we explore extremal, structural, and algorithmic problems involving the partitioning of combinatorial structures. We begin by considering problems from the theory of graph cuts. It is well known that every graph has a cut containing at least half its edges. We conjecture that (except for one example), given any two graphs on the same vertex set, we can partition the vertices so that at least half the edges of each graph go across the partition. We give a simple algorithm that comes close to proving this conjecture. We also prove, using probabilistic methods, that the conjecture holds for certain classes of graphs. We consider an analogue of the graph cut problem for posets and determine which graph cut results carry over to posets. We consider both extremal and algorithmic questions, and in particular, we show that the analogous maxcut problem for posets is polynomial-time solvable in contrast to the maxcut problem for graphs, which is NP-complete. Another partitioning problem we consider is that of obtaining a regular partition (in the sense of the Szemeredi Regularity Lemma) for posets, where the partition respects the order of the poset. We prove the existence of such order-preserving, regular partitions for both the comparability graph and the covering graph of a poset, and go on to derive further properties of such partitions. We give a new proof of an old result of Frankl and Furedi, which characterises all 3-uniform hypergraphs for which every set of 4 vertices spans exactly 0 or 2 edges. We use our new proof to derive a corresponding stability result. We also look at questions concerning an analogue of the graph linear extension problem for posets.
IBEX observations of heliospheric energetic neutral atoms: Current understanding and future directions

The Interstellar Boundary Explorer (IBEX) has provided the first energy‐resolved all‐sky maps of energetic neutral atom (ENA) emissions from the heliosphere's boundary with the local interstellar medium (LISM). The IBEX maps reveal, superposed on a global ENA background, an enigmatic “ribbon” of enhanced ENA emission, a feature unpredicted by theory and numerical simulations and requiring a new paradigm for the heliosphere/LISM interaction. The ribbon appears to be ordered by the interstellar magnetic field; it is up to ∼3 times brighter than the background emission and spectrally distinct from it. The ribbon's origin, whether inside or outside the heliopause or at more exotic locations in the LISM, is unknown. Here, we review the various hypotheses that have been proposed to explain the ribbon as well as what we have learned from the IBEX sky maps about the ENAs' parent ion populations and about the structure, dynamics, and properties of the outer heliosphere and nearby interstellar medium. We conclude with a brief mention of new IBEX results on lunar and magnetospheric ENAs and a preview of a possible future mission that builds on the successes of IBEX as we continue to explore our home in the galaxy.
The Role of Reactive Oxygen Species in Plant Response to Radiation

Radiation is widespread in nature, including ultraviolet radiation from the sun, cosmic radiation and radiation emitted by natural radionuclides. Over the years, the increasing industrialization of human beings has brought about more radiation, such as enhanced UV-B radiation due to ground ozone decay, and the emission and contamination of nuclear waste due to the increasing nuclear power plants and radioactive material industry. With additional radiation reaching plants, both negative effects including damage to cell membranes, reduction of photosynthetic rate and premature aging and benefits such as growth promotion and stress resistance enhancement have been observed. ROS (Reactive oxygen species) are reactive oxidants in plant cells, including hydrogen peroxide (H2O2), superoxide anions (O2•−) and hydroxide anion radicals (·OH), which may stimulate the antioxidant system of plants and act as signaling molecules to regulate downstream reactions. A number of studies have observed the change of ROS in plant cells under radiation, and new technology such as RNA-seq has molecularly revealed the regulation of radiative biological effects by ROS. This review summarized recent progress on the role of ROS in plant response to radiations including UV, ion beam and plasma, and may help to reveal the mechanisms of plant responses to radiation.
High Efficiency and Full MPPT Range Partial Power Processing PV Module-Integrated Converter

To increase the energy yield of photovoltaic (PV) systems in the presence of module-level power mismatches, maximum power point tracking (MPPT) should be performed by converters at module level. Using module-level converters at the output of the PV panels adds a constant loss even when there is no power mismatch, which increases the overall system losses and compromises part of the energy yield improvement. To decrease this constant loss especially when there is no power mismatch, partial power processing (PPP) concept is used in this article to achieve a new high-frequency and high-efficiency module-integrated PV converter, which can achieve full range MPPT and maximum possible efficiency when there is no mismatch. To overcome the challenge of limited MPPT range for partial power converters, a special pulse density modulation technique is proposed, which preserves the merits of PPP and renders full range MPPT. A 220-W prototype converter is implemented to justify the converter principal of operation and analyses. The proposed converter reached 99.6%–96.5% efficiency for the power mismatches in the PV module ranging from 0% to 50% of the maximum module power generation capability, respectively. The efficiency drop is shown to be linear with power mismatch level without any abrupt reductions that is commonly observed in conventional PV module-integrated converters.
Faulty branch identification in passive optical networks using machine learning

Passive optical networks (PONs) have become a promising broadband access network solution thanks to their wide bandwidth, low-cost deployment and maintenance, and scalability. To ensure a reliable transmission, and to meet service level agreements, PON systems have to be monitored constantly in order to quickly identify and localize network faults and thus reduce maintenance costs, minimize downtime, and enhance quality of service. Typically, a service disruption in a PON system is mainly due to fiber cuts and optical network unit (ONU) transmitter/receiver failures. When the ONUs are located at different distances from the optical line terminal, the faulty ONU or branch can be identified by analyzing the recorded optical time domain reflectometry (OTDR) traces. OTDR is a technique commonly used for monitoring of fiber optic links. However, faulty branch isolation becomes very challenging when the reflections originate from two or more branches with similar length overlap, which makes it very hard to discriminate the faulty branches given the global backscattered signal. Recently, machine learning (ML)-based approaches have shown great potential for managing optical faults in PON systems. Such techniques perform well when trained and tested with data derived from the same PON system. But their performance may severely degrade if the PON system (adopted for the generation of the training data) has changed, e.g., by adding more branches or varying the length difference between two neighboring branches, etc. A re-training of the ML models has to be conducted for each network change, which can be time consuming. In this paper, to overcome the aforementioned issues, we propose a generic ML approach trained independently of the network architecture for identifying the faulty branch in PON systems given OTDR signals for the cases of branches with close lengths. Such an approach can be applied to an arbitrary PON system without requiring to be re-trained for each change of the network. The proposed approach is validated using experimental data derived from the PON system.
How leaderboard positions shape our motivation: the impact of competence satisfaction and competence frustration on motivation in a gamified crowdsourcing task

PurposeGamification is a booming motivational approach in information systems. Leaderboards play a key role in gamification; however, there are mixed findings regarding the heterogeneous motivational impacts of leaderboard positions. This study aims to clarify the motivational effects of high and low leaderboard positions by assembling diverse behavioral measures and self-reports. The measures used in this study shed a light on the quantitative and qualitative dynamics of motivation facilitated by leaderboard positions. The authors inspect motivation in relation to satisfaction and frustration of competence need.Design/methodology/approachThe authors conducted an online experiment set in a crowdsourcing context, asking the participants to compete in an image tagging game. Participants' leaderboard positions were manipulated to be either high or low for five consecutive rounds. The number of clicks, tags, duration of tagging and persistence on the task were measured as indicators of motivation.FindingsHigh ranks on leaderboards induced complacent behaviors choosing easy ways to maintain their positions, while low ranks led the participants to stick to the right process of the task with intensified motivation round after round. However, neither of the motivations seemed to be of intrinsic nature.Originality/valueThe present study provides conclusive evidence on the varying motivational impact of leaderboard positions. The authors also demonstrate how the “needs-as-motive” model (Sheldon and Gunz, 2009) applies to gamification. Its implications in self-determination theory and gamification literature are discussed.