bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing surface finish in FDM-printed polycarbonate spur gears through abrasive flow finishing: insights from physics and material science perspectives
Authors: Meena Rajhans , Hashmi Abdul Wahab , Iqbal Faiz , Ahmad Shadab , Prakash Chander , Katiyar Jitendra Kumar , Mali Harlal Singh , Meena Anoj
Published: June 2024

In recent times, the usage of polymers has experienced notable growth across diverse manufacturing sectors. Polymeric gears, integral to automation, material handling systems, toys, and household appliances, have become ubiquitous. Although additive manufacturing techniques, especially Three-Dimensional (3D) printing, offer versatile applications, they grapple with challenges, notably poor surface finishing attributed to layer accumulation. This work explores the field of abrasive flow machining (AFM) in experimental settings using FDM-printed polymeric gears. The AFM medium concoction involves coal ash powder as the foundational material, EDM oil as the carrier fluid, and the infusion of glycerin as additives. Rigorous investigations were undertaken to pinpoint the optimal viscosity of the AFM medium and refine process parameters with a central focus on enhancing surface quality. A Taguchi L9 Design of Experiment (DOE) was meticulously crafted for parameter optimization using the Minitab statistical software. The investigation established a functional relationship between the output parameter (surface roughness) and key input variables (layer thickness, abrasive percentage, abrasive mesh size, and finishing time). The maximum level of AFM media optimization was attained at 33% abrasive concentration, 220 abrasive mesh size, and 60% liquid synthesizer. Additionally, the results of the investigation showed that a media viscosity of 0.50 Pa-sec, layer thickness of 0.1, and culminating time of 45 min were the optimal values for the most % improvement in surface roughness. The initial surface roughness underwent a profound reduction from 12.30 μm to 0.30 μm, marking an exceptional improvement of 97.56%. This inquiry contributes significant insights into the refinement of AFM parameters for elevating the surface finish of FDM-printed polymeric gears, promising enhanced performance across diverse applications.
MHD nonlinear thermally radiative Ag − TiO
2/H
2
O hybrid nanofluid flow over a stretching cylinder with Newtonian heating and activation energy
Authors: Rath Chinmoy , Nayak Anita
Published: June 2024

Hybrid nanofluids are significant in biomedical, industrial, transportation, as well as several engineering applications due to their high thermal conductivity and mass transfer enhancement nature in contrast to regular fluids and nanofluids. Taking this into consideration, the present problem explores the flow of hybrid nanofluid (Ag − TiO
2/H
2
O) over a stretching cylinder subject to Newtonian heat and mass conditions. The novel aspect of the current work is to analyze the heat and mass transfer characteristics of MHD hybrid nanofluid flow on Darcy-Forchheimer porous medium in addition to activation energy, nonlinear thermal radiation, heat generation/absorption, viscous and Joulian dissipation. Further, Silver (Ag) and Titanium oxide (TiO
2) are the constituent nanoparticles of the water-based hybrid nanofluid owing to their stable chemical features and extensive industrial manufacturing. By introducing suitable similarity transformations, the governing partial differential equations (PDEs) of the developed model are reduced to ordinary differential equations (ODEs), and then the numerical solution is procured with shooting technique by using MATLAB solver bvp4c. The influence of the pertinent parameters is depicted graphically and described elaborately. The analysis indicates that velocity exhibits a declining trend against the permeability and Forchheimer parameters, while the temperature profiles show opposite behavior. The radiation and conjugate heat parameters (R, γ
1) upgrade the heat transfer rate, while the curvature and conjugate mass parameters (α

c
, γ
2) amplify the mass transfer rate. The maximum heat transfer rate of Ag − TiO
2/H
2
O hybrid nanofluid is 2.3344 attained for γ
1 = 0.6. The investigation demonstrates larger heat and mass transfer rates for Ag − TiO
2/H
2
O hybrid nanofluid than Ag − H
2
O nanofluid. The outcomes of the present investigation have practical applications in conjugate heat transfer over fins, development of vaccines, effluent treatment plants, solar cells, heat exchangers, and many more. An excellent agreement is achieved on comparing our numerical results with the published results in the literature.
Cherenkov second harmonic generation of femtosecond laser pulses in a homogeneous nonlinear crystal
Authors: Vyunishev A M , Chirkin A S
Published: June 2024

In experiments on second harmonic (SH) generation (SHG), a conical structure of radiation has been observed. In the present study, a non-stationary theory of SH excitation of ultrashort laser pulses with phase modulation has been developed, which explains the properties of such a structure as Cherenkov radiation. Under phase-mismatched interactions, a maximum of the SH spectrum is observed at the Cherenkov angle, which is determined by the ratio of the SH and laser radiation phase velocities. It is shown that tightly focused laser beams are preferred to observe Cherenkov SHG. The SH spectral width depends on the group velocity mismatch and is more complicated on the excited radiation spectrum. The SH energy can be proportional to the crystal length or group delay length depending on their ratio. We also demonstrate that a complex angular distribution of spectral components (an angular chirp) appears within the SH cross-section.
Investigations on the interaction of laser parameters for efficient microdrilling of NiTiV smart alloy system
Authors: Arun A , Santosh S , Rajkumar K
Published: June 2024

Ni–Ti shape memory alloys (SMAs) are popular in current research due to their usefulness and mechanical properties. At different temperatures, Ni–Ti alloys transition from austenite to martensite. To restore high-temperature memory in nickel-titanium SMAs, vanadium (V) is added as an alloying element. For Ni–Ti-based SMAs, the fiber laser is one of the best machining procedures for bio-implants, actuators, and aircraft engine parts. Using a Box–Behnken design to experiment with laser power, nozzle distance, cutting speed, and frequency, this study examines fiber laser micro-drilled Ni50Ti48V2 SM alloy material removal and hole taper angle. By increasing power (P), frequency (F), and cutting speed (C
S
), Ni50Ti48V2 alloy material removal rate (MRR) increased by 75.79%. The hole taper angle (HTA) dropped 75.33% when cutting speed, laser power and frequency decreased. Lowering cutting speed and laser power increases micro-hole circularity and reduces HTA. Upon surface topographical inspection, debris and molten materials were found on the drilled surface. The flow of nitrogen gas caused materials to diffuse on the Ni50Ti48V2 alloy’s entry and exit surfaces, changing surface roughness. High parameters influence surface roughness, HTA, and circularity due to nitrogen gas flow. The material’s DSC and XRD tests confirmed its suitability for biomedical microhole production.
Different topological phase transitions in the Su–Schrieffer–Heeger model under different disorder structures
Authors: Gu 古 Yan 燕 , Lu 陆 Zhanpeng 展鹏
Published: June 2024

We investigate the topological phase transition in the Su–Schrieffer–Heeger model with the long-range hopping and quasi-periodic modulation. By numerically calculating the real-space winding number, we obtain topological phase diagrams for different disordered structures. These diagrams suggest that topological phase transitions are different by selecting the specific disordered structure. When quasi-periodic modulation is applied to intracell hopping, the resulting disorder induces topological Anderson insulator (TAI) phase with high winding number (W = 2), but the topological states are destroyed as the disorder increases. Conversely, when intercell hoppings are modulated quasi-periodically, both TAI phase and the process of destruction and restoration of topological zero modes can be induced by disorder. These topological states remain robust even under strong disorder conditions. Our work demonstrates that disorder effects do not always disrupt topological states; rather, with a judicious selection of disordered structures, topological properties can be preserved.
Successful prediction of tokamak transport in the L-mode regime
Authors: Staebler G.M. , Park J.M. , Hassan E. , Angioni C. , Fable E. , Bourdelle C. , Kinsey J.E. , Holland C. , Belli E.A. , Neiser T. , Candy J. , Waltz R.E.
Published: June 2024

A long standing shortfall in the predicted L-mode edge energy transport by reduced quasi-linear models of gyrokinetic turbulent transport has been resolved. The improved model TGLF-SAT2 has higher fidelity to gyrokinetic simulations of the electron-scale contribution to the electron energy transport and the ion-scale flux surface shape dependence of energy transport. The success of TGLF-SAT2 in predicting the L-mode and Ohmic edge profiles is critical to whole pulse simulation and opens the door to prediction of the H-mode power threshold.
Gyrokinetic simulations of electrostatic microturbulence in ADITYA-U tokamak with argon impurity
Authors: Singh Tajinder , Shah Kajal , Sharma Deepti , Ghosh Joydeep , Jadeja Kumarpalsinh A. , Tanna Rakesh L. , Chowdhuri M.B. , Lin Zhihong , Sen Abhijit , Sharma Sarveshwar , Kuley Animesh
Published: June 2024

The effect of impurity on the electrostatic microturbulence in ADITYA-U tokamak is assessed using global gyrokinetic simulations. The realistic geometry and experimental profiles of the ADITYA-U are used, before and after argon gas seeding, to perform the simulations. Before the impurity seeding, the simulations show the existence of the trapped electron mode (TEM) instability in three distinct regions on the radial-poloidal plane. The mode is identified by its linear eigenmode structure and its characteristic propagation in the electron diamagnetic direction. The simulations with Ar1+ impurity ions in the outer-core region show a significant reduction in the turbulence and transport due to a reduction in the linear instability drive, with respect to the case without impurity. A decrease in particle and heat transport in the outer-core region modifies the plasma density profile measured after the impurity seeding. It, thus, results in the stabilization of the TEM instability in the core region. Due to the reduced turbulence activity, the electron and ion temperatures in the central region increase by about 10%.
Corrigendum: Towards a more realistic MELCOR model for a dry cask for spent nuclear fuel. Part I: sensitivity studies. (2024 J. Phys.: Conf. Ser. 2685 012043)
Authors: Angelucci M , Paci S
Published: June 2024

Please see Article PDF for corrigendum text.
Large agri-food corporations in the global staple and cash crops markets: a quantitative analysis of rice and coffee through the virtual water perspective
Authors: Baronchelli Adelaide , Vallino Elena , Dalmazzone Silvana , Ridolfi Luca , Laio Francesco
Published: June 2024

The paper investigates the influence of major food corporations on global rice and coffee markets from 2013 to 2022, with a focus on market presence and water usage. It uses detailed data from the Euromonitor Passport and the CWASI datasets to analyze environmental impacts and virtual water (VW) flows at the company level, addressing gaps in the existing literature. Key findings show that although rice sales are larger than those of coffee in quantity, coffee embeds a higher total water use due to its greater unit water footprint (WF). The rice market is less internationalized and concentrated compared to the coffee market, where a few companies hold significant market shares across multiple countries. In 2022, the top 12 rice-selling companies control 16% of the global rice WF, exceeding the combined WF of the top three rice-importing nations. Similarly, the top 15 coffee-selling companies command 55% of the global roasted coffee WF, with significant disparities in VW quantities compared to major importing nations. The coffee market exhibits a higher number of companies with larger shares of WF than volumes, with this disparity increasing over time. Furthermore, more countries exhibit high and moderate concentration indices for coffee sales compared to rice. These findings highlight the considerable concentration of water resources among large companies, particularly in the coffee sector. The paper emphasizes the importance of considering the environmental implications of corporate activities in food supply chains, providing valuable insights for sustainability efforts in the agri-food industry.
Rethinking climate agreements: self-enforcing strategies for emission reduction through sanctions
Authors: Lampert Adam
Published: June 2024

Although climate change is expected to cause significant negative impacts, climate treaties give hope for reducing greenhouse gas (GHG) emissions, potentially leading to less severe climate change. However, climate change is a public bad: If each country aims to maximize its own benefit, some countries might free ride and continue to emit GHGs. Consequently, climate treaties have seen limited success, and a central question is how future treaties can achieve GHG emission reduction and also be ‘self-enforcing’—where participating countries have no incentive to withdraw or modify their contributions. Here we examine a dynamic negotiation process involving multiple countries, each deciding whether and when to join the agreement and whether to penalize non-participants. In particular, we distinguish between (1) indirect punishment, in which countries invest less in emission reduction in response to non-compliance of other countries, and (2) direct punishment, in which countries impose sanctions, such as punitive tariffs, against countries that do not comply. We analyze the negotiation process using evolutionary game theory. We show that how the two types of punishment are implemented greatly affects the agreement’s outcome. In particular, an efficient combination of the punishments could lead to more desirable self-enforcing agreements. These findings indicate that integrating punitive measures with an effective negotiation framework could result in more desirable climate agreements.
Effect of initial conditions on current fluctuations in non-interacting active particles
Authors: Jose Stephy , Rosso Alberto , Ramola Kabir
Published: June 2024

We investigate the effect of initial conditions on the fluctuations of the integrated density current across the origin (x = 0) up to a given time t in a one-dimensional system of non-interacting run-and-tumble particles. Each particle has initial probabilities

f

+

and

f

−

to move with an initial velocity +v and −v respectively, where v > 0. We derive exact results for the variance (second cumulant) of the current for quenched and annealed averages over the initial conditions for the magnetization and the density fields associated with the particles. We show that at large times, the variance displays a

t

behavior, with a prefactor contingent on the specific density initial conditions used. However, at short times, the variance displays either linear t or quadratic t
2 behavior, which depends on the combination of magnetization and density initial conditions, along with the fraction

f

+

of particles in the positive velocity state at t = 0. Intriguingly, if

f

+

=
0

, the variance displays a short time t
2 behavior with the same prefactor irrespective of the initial conditions for both fields.
Spacetime symmetries and geometric diffusion
Authors: Basquens Marc , Lasanta Antonio , Mompó Emanuel , Varo Valle , J S Villaseñor Eduardo
Published: June 2024

We examine relativistic diffusion through the frame and observer bundles associated with a Lorentzian manifold (M, g). Our focus is on spacetimes with a non-trivial isometry group, and we detail the conditions required to find symmetric solutions of the relativistic diffusion equation. Additionally, we analyze the conservation laws associated with the presence of Killing vector fields on (M, g) and their implications for the expressions of the geodesic spray and the vertical Laplacian on both the frame and the observer bundles. Finally, we present several relevant examples of symmetric spacetimes.
Correlational study of multiscale analysis and the metrological characteristics of areal surface topography measuring instruments
Authors: Eifler M , Hering-Stratemeier J , von Freymann G , Brown C A , Seewig J
Published: June 2024

With the metrological characteristics, an effective framework for the calibration, adjustment, performance specification and verification of areal surface topography measuring instruments has been introduced. The characteristics have been thoroughly researched and analyzed for their different applications. Each characteristic provides specific information for a certain axis or feature of the measuring instrument. This enables an uncertainty estimation and a comparability of different measuring instruments. In this study, the comparison results of metrological characteristics are correlated with information obtained from multiscale analysis. With this examination it can be shown that both, metrological characteristics and multiscale analysis include significant information about transfer behaviors of surface structures, which can be applied advantageously for a calibration, performance verification and uncertainty determination of areal surface topography measuring instruments.
Ni–Cr dental alloys - porcelain firing impact on corrosion properties and surface characteristics
Authors: Rylska Dorota , Sokolowski Grzegorz , Sokolowski Krzysztof
Published: June 2024

Biocompatibility is a critical aspect of the use of materials in the human body. The use of base metal alloys in dentistry is primarily regulated by health and safety standards set by regulatory authorities in various countries. The porcelain-fused-to-metal (PFM) process applied to Ni-Cr dental alloys can alter their properties, particularly in terms of corrosion and surface characteristics. This study aimed to assess the effect of the heat processing used for dental porcelain firing on these properties. The two casted alloys: Ceramic N and Ivoclar Vivadent 4all, used in the study were characterized by analyzing the microstructure by scanning electron microscopy (SEM), composition with energy dispersive x-ray spectroscopy (EDS), hardness, surface profile and electrochemical corrosion resistance (Ecorr, jcorr, polarization curve, Ebr and electrochemical impedance spectroscopy (EIS) results), as well as ions release before and after the simulated porcelain firing. Based on the conducted research the following conclusions can be drawn: Analyzes of the material characteristics before and after the simulation showed that the discussed process, although it does not cause the formation of chemical impurities on the surface of the alloys, results in changes in the chemical composition and structure of surface oxides, increases roughness and reduces hardness. The results of the corrosion examinations showed a deterioration in anti-corrosion properties after the simulation. The statistically significant decrease in corrosion resistance may result from the increased heterogeneity of the surface oxide layers and partial changes in their composition.
Thermal annealing of radiation damages produced by swift 14N and 16O ions in LiF crystals
Authors: Sorokin M V , Malikova Zh B , Dauletbekova A K , Baubekova G , Aralbayeva G M , Akilbekov A T
Published: June 2024

Annealing of color centers was studied in lithium fluoride crystals, irradiated with 23-MeV nitrogen and 28-MeV oxygen ions. Basing on the optical absorption spectroscopy and reaction-rate modelling, a new interpretation of the annealing kinetics at the practically important temperatures below 500 K is suggested. Proposed model explains simultaneous decrease of the F and F2/F3
+ peaks as a result of migration of the F centers and formation of larger aggregates, and does not include additional assumptions about impurities and cation vacancies. It specifies the migration energy of the F centers in the ground state to be about 1.3 eV, that corresponds to earlier studies.
An innovative approach to effective breeding blanket design for future fusion reactors
Authors: LIU 刘 Changle 常乐 , LI 李 Lei 磊 , HE 何 Yanzi 严字 , ZHANG 张 Peng 鹏 , ZHOU 周 Yu 宇 , SONG 宋 Jun 军 , WU 武 Songtao 松涛
Published: June 2024

An effective breeding blanket is critical to support tritium self-sufficiency for future fusion reactors. The difficulty is to achieve tritium breeding ratio (TBR) target of 1.05 or more. This paper presents a new design approach to the blanket design process. It indicates that fusion blanket design is affected by universal functions based on iterations. Three aspects are worth more attention from fusion engineers in the future. The first factor is that the iterations on the material fractions affect not only structure scheme but also TBR variation. The second factor is the cooling condition affecting final TBR due to the change of the structure material proportion. The third factor is temperature field related to the tritium release. In particular, it is suggested that the statistical calculation of effective TBR must be under reasonable control of the blanket temperature field. This approach is novel for blanket engineering in development of a fusion reactor.
Deciphering split ring resonators: understanding theoretical validation and simulation implications
Authors: Mishra Piyush , Singh Bhupendra Pratap , Agrawal Ved Varun
Published: June 2024

This study presents a comparative analysis of analytical calculations and simulation results of a single-ring split ring resonator (SRR). A simulated SRR made of aluminum, designed in high frequency structure simulator (HFSS), with the resonant frequency of 3.97 GHz with transmission loss of −47.7 dB. The initial gap, width, and thickness of the ring are set at 1 mm, 1 mm, and 3 mm, respectively. These geometrical parameters are subsequently varied in simulations, and theoretical calculations are conducted for each variation using Python 3.10 code to facilitate comparative analysis. The analytical calculations reveal certain limitations in accurately modeling the impact of fringing and radiation, particularly when dealing with smaller dimensions. Although there exist slight disparities between the simulated and calculated outcomes, it is evident that the theoretically derived results exhibit a close correspondence with simulated responses, particularly for dimensions that are not excessively small. This observation underscores the confirmation that an augmentation in the gap of the Split Ring Resonator (SRR) leads to an elevation in the resonant frequency. Furthermore, by maintaining a constant inner radius and adjusting the outer radius to modulate the width of the SRR, a decrease in the resonant frequency is noted with an increase in the width of the metallic ring. Similarly, an increase in the thickness of the ring contributes to a reduction in the resonant frequency This comprehensive investigation provides a valuable methodology for corroborating theoretically derived results with simulation data. Additionally, the research underscores the diverse resonances that can be achieved by fine-tuning the gap, width, and thickness of the split ring resonator, highlighting the significance of selecting these dimensions carefully to attain specific resonant frequencies.
Unlearning regularization for Boltzmann machines
Authors: Ventura Enrico , Cocco Simona , Monasson Rémi , Zamponi Francesco
Published: June 2024

Boltzmann machines (BMs) are graphical models with interconnected binary units, employed for the unsupervised modeling of data distributions. When trained on real data, BMs show the tendency to behave like critical systems, displaying a high susceptibility of the model under a small rescaling of the inferred parameters. This behavior is not convenient for the purpose of generating data, because it slows down the sampling process, and induces the model to overfit the training-data. In this study, we introduce a regularization method for BMs to improve the robustness of the model under rescaling of the parameters. The new technique shares formal similarities with the unlearning algorithm, an iterative procedure used to improve memory associativity in Hopfield-like neural networks. We test our unlearning regularization on synthetic data generated by two simple models, the Curie–Weiss ferromagnetic model and the Sherrington–Kirkpatrick spin glass model. We show that it outperforms Lp
-norm schemes and discuss the role of parameter initialization. Eventually, the method is applied to learn the activity of real neuronal cells, confirming its efficacy at shifting the inferred model away from criticality and coming out as a powerful candidate for actual scientific implementations.
Fast physical reservoir computing, achieved with nonlinear interfered spin waves
Authors: Namiki Wataru , Nishioka Daiki , Tsuchiya Takashi , Terabe Kazuya
Published: June 2024

Reservoir computing is a promising approach to implementing high-performance artificial intelligence that can process input data at lower computational costs than conventional artificial neural networks. Although reservoir computing enables real-time processing of input time-series data on artificial intelligence mounted on terminal devices, few physical devices are capable of high-speed operation for real-time processing. In this study, we introduce spin wave interference with a stepped input method to reduce the operating time of the physical reservoir, and second-order nonlinear equation task and second-order nonlinear autoregressive mean averaging, which are well-known benchmark tasks, were carried out to evaluate the operating speed and prediction accuracy of said physical reservoir. The demonstrated reservoir device operates at the shortest operating time of 13 ms/5000-time steps, compared to other compact reservoir devices, even though its performance is higher than or comparable to such physical reservoirs. This study is a stepping stone toward realizing an artificial intelligence device capable of real-time processing on terminal devices.
The effect of place of living on social acceptance of shared PV projects in Switzerland
Authors: Ruprecht Sophie
Published: June 2024

In Switzerland, solar power has the greatest potential to further advance the energy transition. As conventional rooftop PV excludes a large share of citizens from personally contributing to climate change mitigation, shared PV (photovoltaics) projects offer a more inclusive alternative, e.g. also for urban residents who are less likely to have the option to install solar panels on their own roof. Thus, investigating people’s preferences depending on the degree of urbanity of their place of residence is crucial to determine socially acceptable PV project designs. Using original Swiss survey data (N = 3000) and applying conjoint analysis, different preferences both depending on respondents’ place of living as well as for different dimensions of social acceptance are found. Most notably, big city residents are generally most in favour of such projects but they exhibit the lowest willingness to actually invest. The conjoint experiment showed that, regarding the DVs of project rating and project choice, only the reimbursement by credit vouchers significantly improved project acceptance for big city residents. This also holds true for rural residents, where, in addition, tax deductions (reimbursement), traffic infrastructure, large consumer roofs (location) and electricity provider were also positively evaluated. For the DV specifying the amount of PV modules bought, no project attribute level managed to significantly increase this number, for which only investment-reducing factors were identified: Residents from big cities invest less when a PV project is located in a skiing area or when the investment is made at an information event. For rural residents, large consumer roofs as a location decrease the scale of an investment. These factors should therefore be avoided when planning a shared PV project in order to maximise investments. Fulfilling respective preferences (i.e. according to projects’ place-based target group) may prove relevant to enhance social acceptance of shared PV projects.
Lipschitz-free spaces over properly metrizable spaces and approximation properties
Authors: Smith Richard , Talimdjioski Filip
Published: June 2024

Let

T
T

be a topological space admitting a compatible proper metric, that is, a locally compact, separable and metrizable space. Let

M

T

\mathcal {M}^T

be the non-empty set of all proper metrics

d
d

on

T
T

compatible with its topology, and equip

M

T

\mathcal {M}^T

with the topology of uniform convergence, where the metrics are regarded as functions on

T
2

T^2

. We prove that the set

A

T
,
1

\mathcal {A}^{T,1}

of metrics

d
∈

M

T

d\in \mathcal {M}^T

for which the Lipschitz-free space

F

(
T
,
d
)

\mathcal {F}(T,d)

has the metric approximation property is a dense set in

M

T

\mathcal {M}^T

, and is furthermore residual in

M

T

\mathcal {M}^T

when

T
T

is zero-dimensional. We also prove that if

T
T

is uncountable then the set

A

f
T

\mathcal {A}^T_f

of metrics

d
∈

M

T

d\in \mathcal {M}^T

for which

F

(
T
,
d
)

\mathcal {F}(T,d)

fails the approximation property is dense in

M

T

\mathcal {M}^T

. Combining the last statement with a result of Dalet, we conclude that for any ‘properly metrizable’ space

T
T

,

A

f
T

\mathcal {A}^T_f

is either empty or dense in

M

T

\mathcal {M}^T

.
Invariant subspaces of contractions with constant characteristic function
Authors: Bhuia Sudip Ranjan
Published: June 2024

We describe all the invariant subspaces of a completely nonunitary contraction

T
c

T_c

with nonzero scalar constant characteristic function

c
c

, where

|

c

|

>
1

|c|>1

. Moreover, we show that

T
c

T_c

and restriction to its invariant subspaces are essentially normal. Using this description of

T
c

T_c

-invariant subspaces, we then identify the hyperinvariant subspaces.
On lax limits in ∞-categories
Authors: Berman John
Published: June 2024

We introduce partially lax limits of

∞
\infty

-categories, which interpolate between ordinary limits and lax limits. Most naturally occurring examples of lax limits are only partially lax; we give examples arising from enriched

∞
\infty

-categories and

∞
\infty

-operads. Our main result is a formula for partially lax limits and colimits in terms of the Grothendieck construction. This generalizes a formula of Lurie for ordinary limits and of Gepner, Haugseng, and Nikolaus for fully lax limits.
Trichotomy for the orbits of a hypercyclic operator on a Banach space
Authors: Li Jian
Published: June 2024

We obtain a trichotomy for the orbits of a hypercyclic operator

T
T

on a separable Banach space

X
X

: (1) every vector is mean asymptotic to zero; (2) generic vectors are absolutely mean irregular; (3) every hypercyclic vector is mean divergent to infinity. Examples of weighted backward shifts on

ℓ
p

\ell ^p

show that all three cases can happen.
Hairer’s multilevel Schauder estimates without regularity structures
Authors: Broux Lucas , Caravenna Francesco , Zambotti Lorenzo
Published: June 2024

We investigate the regularising properties of singular kernels at the level of germs, i.e. families of distributions indexed by points in

R

d

\mathbb {R}^d

. First we construct a suitable integration map which acts on general coherent germs. Then we focus on germs that can be decomposed along a basis (corresponding to the so-called modelled distributions in Regularity Structures) and we prove a version of Hairer’s multilevel Schauder estimates in this setting, with minimal assumptions.
Research trends and knowledge gaps in the ecology of dung beetles (Coleoptera: Scarabaeidae) in savannas
Authors: Reis Nayara L , López-Bedoya Pablo A , Louzada Julio N C
Published: June 2024

Savannas are recognized as one of the world’s most biodiverse ecosystems. However, these environments have the highest rates of habitat loss due to land use and climate-induced alterations in fire regimes. The combination of these threats, along with knowledge gaps in biodiversity, represents formidable challenges to conservation efforts in these regions. Dung beetles, vital for comprehending the impact of land use on savannas, have yet to undergo comprehensive study. To address this gap, we conducted a systematic review of the current state of knowledge regarding dung beetles distributed in savannas within Neotropical, Afrotropical, and Australasia zoogeographic regions. We describe the encompassing geographical distribution, research topics, studied habitats, and key metrics assessed in existing studies. Our results reveal a pronounced focus on Neotropical savannas highlighting a substantial deficit in dung beetle ecology knowledge within Afro-tropical and Australasian savannas. Most articles focused on savanna grasslands, woodlands, and human-introduced habitats such as pastures. The predominant articles focused on community patterns, habitat replacement, and degradation. Noteworthy metrics included abundance, richness, and species composition. Diversity indexes and functional diversity were also relatively well-explored metrics. However, across all zoogeographic regions, aspects of dung beetle behavior, reproductive biology, and physiology remain inadequately explored. In conclusion, urgent research efforts are imperative, emphasizing the need for comprehensive metrics, including biomass, morphometrics, and ecological functions of dung beetles, to advance our understanding of their significance and roles within savannas.
Should patients with exceptional longevity be treated for osteoporosis after a hip fracture?
Authors: Barceló Montserrat , Casademont Jordi , Mascaró Jordi , Gich Ignasi , Torres Olga Herminia
Published: June 2024

Background

There are no studies focusing on treatment for osteoporosis in patients with exceptional longevity after suffering a hip fracture.

Objective

To assess the advisability of initiating treatment for osteoporosis after a hip fracture according to the incidence of new fragility fractures after discharge, risk factors for mortality and long-term survival.

Design

Retrospective review.

Setting

A tertiary university hospital serving a population of ~425 000 inhabitants in Barcelona.

Subjects

All patients >95 years old admitted with a fragility hip fracture between December 2009 and September 2015 who survived admission were analysed until the present time.

Methods

Pre-fracture ambulation ability and new fragility fractures after discharge were recorded. Risk factors for 1-year and all post-discharge mortality were calculated with multivariate Cox regression. Kaplan–Meier survival curve analyses were performed.

Results

One hundred and seventy-five patients were included. Median survival time was 1.32 years [95% confidence interval (CI) 1.065–1.834], with a maximum of 9.2 years. Male sex [hazard ratio (HR) 2.488, 95% CI 1.420–4.358] and worse previous ability to ambulate (HR 2.291, 95% CI 1.417–3.703) were predictors of mortality. After discharge and up to death or the present time, 10 (5.7%) patients had a new fragility fracture, half of them during the first 6 months.

Conclusions

Few new fragility fractures occurred after discharge and half of these took place in the first 6 months. The decision to start treatment of osteoporosis should be individualised, bearing in mind that women and patients with better previous ambulation ability will have a better chance of survival.
Identifying target populations to align with decision-makers’ needs
Authors: Lund Jennifer L , Matthews Anthony A
Published: June 2024

Randomized trials estimate the average treatment effect within individuals who are eligible, invited, and agree to enroll. However, decision-makers often require evidence that extends beyond the trial's enrolled population to inform policy or actions for their specific target population. Each decision-maker has distinct target populations, the composition of which may not often align with that of the trial population. As researchers, we should identify a decision-maker for whom we aim to generate evidence early in the research process. We can then specify a target population of their interest and determine if a policy or action can be informed using results from a trial alone, or if additional complementary real-world data and analysis are required. In this commentary, we outline 5 key groupings of decision-makers: policymakers, payers, purchasers, providers, and patients. We then specify relevant target populations for decision-makers interested in the effectiveness of beta-blockers after a myocardial infarction with preserved ejection fraction. Finally, we summarize the scenarios in which results from a randomized trial may or may not apply to these target populations and suggest relevant analytic approaches that can generate evidence to better align with a decision-maker’s needs.

This article is part of a Special Collection on Pharmacoepidemiology.
Solid-state cultivation of multiple industrial strains of koji mold on different Thai unpolished rice cultivars: biotransformation of phenolic compounds and their effects on antioxidant activity
Authors: Jitpakdee Jirayu , Yamashita Hideyuki , Nakagawa Takuro , Nitoda Teruhiko , Kanzaki Hiroshi
Published: June 2024

Colored rice is abundant in polyphenols, and koji molds have potential for biotransformation. This study aimed to produce Thai-colored rice koji to study its polyphenolic biotransformation. Four industrial koji mold strains: Aspergillus oryzae 6001, A. oryzae 6020, A. sojae 7009, and A. luchuensis 8035, were cultivated on unpolished Thai-colored rice (Riceberry and Sangyod), unpolished Thai white rice (RD43), and polished Japanese white rice (Koshihikari). We discovered that koji molds grew on all the rice varieties. Methanol extracts of all rice kojis exhibited an approximately 2-fold or greater increase in total phenolic content and DPPH antioxidant activity compared to those of steamed rice. Moreover, quercetin, quercetin-3-O-glucoside, isorhamnetin-3-O-glucoside, ferulic acid, caffeic acid, protocatechuic acid, vanillic acid, (+)-catechin, and (–)-epicatechin content increased in Riceberry and Sangyod koji samples. Consequently, Aspergillus solid-state cultivation on unpolished Thai-colored rice exhibited higher functionalization than the cultivation of unpolished Thai white rice and polished Japanese white rice.
Differentiable phylogenetics via hyperbolic embeddings with Dodonaphy
Authors: Macaulay Matthew , Fourment Mathieu
Published: June 2024

Motivation

Navigating the high dimensional space of discrete trees for phylogenetics presents a challenging problem for tree optimization. To address this, hyperbolic embeddings of trees offer a promising approach to encoding trees efficiently in continuous spaces. However, they require a differentiable tree decoder to optimize the phylogenetic likelihood. We present soft-NJ, a differentiable version of neighbour joining that enables gradient-based optimization over the space of trees.

Results

We illustrate the potential for differentiable optimization over tree space for maximum likelihood inference. We then perform variational Bayesian phylogenetics by optimizing embedding distributions in hyperbolic space. We compare the performance of this approximation technique on eight benchmark datasets to state-of-the-art methods. Results indicate that, while this technique is not immune from local optima, it opens a plethora of powerful and parametrically efficient approach to phylogenetics via tree embeddings.

Availability and implementation

Dodonaphy is freely available on the web at https://www.github.com/mattapow/dodonaphy. It includes an implementation of soft-NJ.
Efficient construction and utilization of k-ordered FM-indexes with kISS for ultra-fast read mapping in large genomes
Authors: Yang Zheng-Dao , Kuo Hsuan-Yu , Hsieh Po-Wei , Hung Jui-Hung
Published: June 2024

Motivation

The Full-text index in Minute space (FM-index) is a memory-efficient data structure widely used in bioinformatics for solving the fundamental pattern-matching task of searching for short patterns within a long reference. With the demand for short query patterns, the k-ordered concept has been proposed for FM-indexes. However, few construction algorithms in the state of the art fully exploit this idea to achieve significant speedups in the pan-genome era.

Results

We introduce the k-ordered induced suffix sorting (kISS) for efficient construction and utilization of k-ordered FM-indexes. We present an algorithmic workflow for building k-ordered suffix arrays, incorporating two novel strategies to improve time and memory efficiency. We also demonstrate the compatibility of integrating k-ordered FM-indexes with locate operations in FMtree. Experiments show that kISS can improve the construction time, and the generated k-ordered suffix array can also be applied to FMtree without any additional in computation or memory usage.

Availability and implementation

https://github.com/jhhung/kISS.
International study on prevalence of itch: examining the role of itch as a major global public health problem
Authors: Yosipovitch Gil , Skayem Charbel , Aroman Marketa Saint , Taieb Charles , Inane Medhi , Hayoun Yaron Ben , Cullel Nuria Perez , Baissac Catherine , Halioua Bruno , Richard Marie Aleth , Misery Laurent
Published: June 2024

Background

Very few studies have evaluated the global prevalence of pruritus.

Objectives

To assess its prevalence according to age, sex, ethnicity and geographic region.

Methods

An international cross-sectional study was conducted in 20 countries from January to April 2023. Participants were asked to complete a questionnaire on sociodemographics, and to confirm the presence or absence of a skin disease in the last 12 months and the presence or absence of pruritus in the last 7 days.

Results

The studied sample included 50 552 individuals. The worldwide prevalence of pruritus was 39.8%. The age group ≥ 65 years had the highest prevalence (43.3%). The prevalence was 40.7% among women and 38.9% among men (P < 0.001). There was no significant difference between ethnicities (P = 0.14). Compared with North America (41.2%), the prevalence of pruritus was significantly lower in Europe (35.9%, P < 0.001), Australia (38.4%, P = 0.017), East Asia (40.2%, P = 0.04) and Latin America (36.5%, P < 0.001), and higher in Africa (45.7%, P = 0.007). No significant difference was found with the Middle East (40.2%, P = 0.36). The prevalence of pruritus in BRICS countries (40.3%) was significantly higher than that in developed countries (38.7%) (P < 10–3).

Conclusions

Out analysis is limited because there is no information about the severity or type (acute, chronic) of pruritus. The global prevalence of pruritus revealed age, sex and geographic region differences, with no ethnic differences.
Preoperative prediction of renal fibrous capsule invasion in clear cell renal cell carcinoma using CT-based radiomics model
Authors: Zhang Yaodan , Zhao Jinkun , Li Zhijun , Yang Meng , Ye Zhaoxiang
Published: June 2024

Objectives

To develop radiomics-based classifiers for preoperative prediction of fibrous capsule invasion in renal cell carcinoma (RCC) patients by CT images.

Methods

In this study, clear cell RCC (ccRCC) patients who underwent both preoperative abdominal contrast-enhanced CT and nephrectomy surgery at our hospital were analysed. By transfer learning, we used base model obtained from Kidney Tumour Segmentation challenge dataset to semi-automatically segment kidney and tumours from corticomedullary phase (CMP) CT images. Dice similarity coefficient (DSC) was measured to evaluate the performance of segmentation models. Ten machine learning classifiers were compared in our study. Performance of the models was assessed by their accuracy, precision, recall, and area under the receiver operating characteristic curve (AUC). The reporting and methodological quality of our study was assessed by the CLEAR checklist and METRICS score.

Results

This retrospective study enrolled 163 ccRCC patients. The semiautomatic segmentation model using CMP CT images obtained DSCs of 0.98 in the training cohort and 0.96 in the test cohort for kidney segmentation, and DSCs of 0.94 and 0.86 for tumour segmentation in the training and test set, respectively. For preoperative prediction of renal capsule invasion, the AdaBoost had the best performance in batch 1, with accuracy, precision, recall, and F1-score equal to 0.8571, 0.8333, 0.9091, and 0.8696, respectively; and the same classifier was also the most suitable for this classification in batch 2. The AUCs of AdaBoost for batch 1 and batch 2 were 0.83 (95% CI: 0.68-0.98) and 0.74 (95% CI: 0.51-0.97), respectively. Nine common significant features for classification were found from 2 independent batch datasets, including morphological and texture features.

Conclusions

The CT-based radiomics classifiers performed well for the preoperative prediction of fibrous capsule invasion in ccRCC.

Advances in knowledge

Noninvasive prediction of renal fibrous capsule invasion in RCC is rather difficult by abdominal CT images before surgery. A machine learning classifier integrated with radiomics features shows a promising potential to assist surgical treatment options for RCC patients.
The Visibility of a Socio-Economic Dimension in Day-to-Day Child and Family Social Work Practice in Wales
Authors: Elliott Martin , Smith Philip , Scourfield Jonathan
Published: June 2024

This study explored how day-to-day social work practice with children and families in Wales responds to poverty, building on case studies already published in the other three UK nations. A case study design was used. The sites were locality teams in two local authorities, differing in their children looked after rates and trajectories of these over time. Qualitative research methods included practice observations; interviews with staff; focus groups; mapping of decision-making processes; and a sample of family case narratives. In one local authority, the range of data was similar to the other UK nation case studies. However, in the second, data collection was adapted to the coronavirus disease-19 (COVID-19) lockdown context. Some evidence was found of narratives that emphasised the cultural, rather than material, aspect of poverty, and blamed parents for making inappropriate spending choices. Poverty alleviation was generally seen as outside of social workers’ control and requiring earlier help before social services involvement. In one of the local authorities, there was some awareness shown of the impact of poverty on parenting. In the other, that took part in the study during 2020, the exacerbating effects of families in lockdown were described, including the lack of family support due to pandemic restrictions.