Feeding Structure Research Articles

Abundance survey of crustacean “y-larvae” (Thecostraca: Facetotecta) over a fringing reef in Okinawa, Japan, with special reference to the two dominant planktotrophic and lecithotrophic naupliar types

Facetotecta, or “y-larvae”, are mysterious planktonic crustaceans that are known only from their larval instars, but which are often assumed to be endoparasitic as adults. Dozens of mostly undescribed forms occur in the shallow-water plankton over a fringing reef at Sesoko Island, Okinawa, Japan. Recently, it has become possible to discriminate the different forms of their nauplius-stage larvae (“y-nauplii”) in a replicable way. A large year-to-year overlap in morphospecies recovered during fieldwork at Sesoko Island in 2018, 2019, and 2023 suggests that a full inventory is close at hand. To date, 49 morphospecies of y-nauplii (8 planktotrophic, 41 lecithotrophic) have been recognized in the area, among which three have been formally described. A detailed analysis of the temporal fluctuations in abundance during October 2023 showed that most morphospecies were rare, but two were particularly common: Type A*, a planktotroph with a long (> 3 weeks) period of naupliar development allowing for long-distance dispersal, and Type AG*, a lecithotroph with a short (3 days) period of development that implies rapid local recolonization. During the survey, both types showed distinct, largely non-overlapping peaks in abundance, related perhaps to their different dispersal/feeding strategies. An examination of the morphology of the swimming/feeding appendages in y-nauplii of Types A* and AG*, together with a mapping of feeding versus non-feeding nauplii on a recent comprehensive phylogeny of Facetotecta, suggests that broader taxonomic coverage of naupliar feeding structures in this group may provide useful information regarding the evolutionary direction of planktotrophy versus lecithotrophy in marine larvae.

High Nutritional Conditions Influence Feeding Plasticity in Pristionchus pacificus and Render Worms Non-Predatory.

Developmental plasticity, the ability of a genotype to produce different phenotypes in response to environmental conditions, has been subject to intense studies in the last four decades. The self-fertilising nematode Pristionchus pacificus has been developed as a genetic model system for studying developmental plasticity due to its mouth-form polyphenism that results in alternative feeding strategies with a facultative predatory and non-predatory mouth form. Many studies linked molecular aspects of the regulation of mouth-form polyphenism with investigations of its evolutionary and ecological significance. Also, several environmental factors influencing P. pacificus feeding structure expression were identified including temperature, culture condition and population density. However, the nutritional plasticity of the mouth form has never been properly investigated although polyphenisms are known to be influenced by changes in nutritional conditions. For instance, studies in eusocial insects and scarab beetles have provided significant mechanistic insights into the nutritional regulation of polyphenisms but also other forms of plasticity. Here, we study the influence of nutrition on mouth-form polyphenism in P. pacificus through experiments with monosaccharide and fatty acid supplementation. We show that in particular glucose supplementation renders worms non-predatory. Subsequent transcriptomic and mutant analyses indicate that de novo fatty acid synthesis and peroxisomal beta-oxidation pathways play an important role in the mediation of this plastic response. Finally, the analysis of fitness consequences through fecundity counts suggests that non-predatory animals have an advantage over predatory animals grown in the glucose-supplemented condition.

A Low-Profile Balanced Dielectric Resonator Filtering Power Divider with Isolation.

A balanced dielectric resonator filtering power divider with isolation performance is proposed. By using the coupling of the TE111y modes between three rectangle dielectric resonators, combined with balanced feed structures, the differential-mode filtering and power dividing functions, as well as the common-mode suppression were achieved effectively. Additionally, by technically utilizing the hollow structure of the stacked substrates, isolation resistor structures are introduced at the two output ports to improve the isolation level of the power divider. It can solve the problem of traditional metal-cavity dielectric resonator filter power dividers being unable to add isolation structures due to structural reasons. Compared with the reported dielectric resonator filtering power dividers, the proposed one has the characters of a lower profile and high isolation. For demonstration, one dielectric resonator filtering power divider was fabricated and measured at 11.65 GHz with the profile of 0.66 λg and an isolation higher than 15 dB. The simulation results are in good agreement with the measured results.

A Miniaturized Loaded Open-Boundary Quad-Ridge Horn with a Stable Phase Center for Interferometric Direction-Finding Systems.

In order to achieve high accuracy in interferometric direction-finding systems, antennas with a stable phase center in the working bandwidth are required. This article proposes a miniaturized loaded open-boundary quad-ridge horn (LOQRH) antenna with dimensions of 40 mm × 40 mm × 49 mm. First, to stabilize the phase center of the antenna, the design builds on the foundation of a quad-ridge horn antenna, where measures such as optimizing the ridge structure and introducing resistive loading were implemented to achieve size reduction. Second, electrically small-sized antennas are more susceptible to the effects of common-mode currents (CMCs), which can reduce the symmetry of the radiation pattern and the stability of the phase center. To avoid the generation of common-mode currents during operation, a self-balanced feed structure was introduced into the proposed antenna design. This structure establishes a balanced circuit and routes the feedline at the voltage null point, effectively suppressing the common-mode current. As a result, the miniaturization of the LOQRH antenna was achieved while ensuring the suppression of the common-mode current, thereby maintaining the stability of the antenna's electromagnetic performance. The measured results show that the miniaturized antenna has a small phase center change of less than 20.3 mm within 2-18 GHz, while the simulated phase center fluctuation is only 14.6 mm. In addition, when taking 18.5 mm in front of the antenna's feed point as the phase center, the phase fluctuation is less than 22.5° within the required beam width. Along with the desired stable phase center, the miniaturized design makes the proposed antenna suitable for interferometric direction-finding systems.

A Review on Multi-Geometrical Antenna Reflector

Parabolic antennas are among the most important devices for long-distance communications because of their significant advantages in terms of directivity, gain, and power handling capabilities. Hat feeds are frequently used as feeders for parabolic antennas because they exhibit low levels of cross-polarisation, low sidelobes, and low reflection coefficients. However, hat feeds possess a limited impedance bandwidth (IBW) range of just 30% and are not suitable for use in wideband applications. More work is being done with the objective of increasing the hat feed’s bandwidth capacity. The fundamental structure of a hat feed comprises a hat sub-reflector, circular waveguide, and dielectric material to provide structural support. The hat feeder had a bandwidth capacity of 10% at first. Later, the Chinese hat feed was introduced and used, resulting in a notable enhancement of the bandwidth, with an increase of 18%. The hat feed's geometric structure is redesigned with the help of a generic algorithm optimisation to further enhance the bandwidth, resulting in a 33% improvement.

ENFORCEMENT OF STATE FEES IN ECONOMIC COURTS: A COMPARATIVE LEGAL ANALYSIS

Objective: Evaluate the state duty system in economic courts in Uzbekistan, with a focus on its impact on the affordability and accessibility of legal services. The study explores the financial barriers that individuals and businesses, particularly small and medium-sized enterprises (SMEs), face when navigating economic disputes in the judicial system. Method: The study employs a comparative-legal approach, utilizing logical, empirical, and specific scientific methods tailored to legal studies. It involves analyzing existing legal frameworks through comparison with practices in neighboring countries, such as Russia and Kazakhstan, using both qualitative and quantitative analysis to understand the differences in state duty structures and enforcement mechanisms. Results: The current state duty system in Uzbekistan is significantly higher than in neighboring countries, creating financial burdens for SMEs and individuals. The research reveals that while economic courts are essential for ensuring justice, the high state fees, coupled with a lack of flexibility in fee structures, make access to justice more difficult, particularly for smaller businesses. The study suggests potential reforms, such as introducing caps on state fees and adopting more flexible fee structures similar to those in Russia and Kazakhstan, which could improve accessibility and fairness. Novelty: This research offers a unique contribution by comparing Uzbekistan’s economic court fee structure with those of neighboring countries, providing insights into the potential benefits of adopting foreign legal practices to enhance judicial accessibility. Additionally, it presents practical recommendations for reforming the state duty system, a topic that has been relatively underexplored in the context of post-Soviet legal systems.

Pristionchus - Beetle associations: Towards a new natural history.

The free-living nematode Pristionchus pacificus has been established as a model system in integrative evolutionary biology by combining laboratory studies with field work and evolutionary biology. Multiple genetic, molecular and experimental tools and a collection of more than 2,500 P. pacificus strains and more than 50 Pristionchus species, which are available as living cultures or frozen stock collections, support research on various life history traits. Species of Pristionchus exhibit a number of complex traits unknown from Caenorhabditis elegans and most other free-living nematodes. First, P. pacificus can form two alternative mouth forms, an example of developmental plasticity that is increasingly studied to investigate the role of plasticity as a facilitator of evolutionary novelty. More than a decade of work has identified associated genetic and epigenetic mechanisms and revealed the evolutionary and ecological significance of feeding structure plasticity. Second, one of the two mouth morphs results in predatory behavior against other nematodes and is currently used to investigate the neurobiology of predation. Third, potential predation results in the risk of cannibalism among conspecifics. Strikingly, Pristionchus nematodes have developed a self-recognition system that allows the distinction of self (kin) and non-self. Given all these organismal features, this nematode has recently been considered a key example for research towards a new natural history (West-Eberhard, 2024). Here, I summarize recent work on Pristionchus with a focus on a 'new natural history'. In addition, I review some recent studies that indicate an interaction of Pristionchus with EPNs that was suggested based on various surveys in different ecological habitats.

Dual- and triple-band quasi-elliptic bandpass filters based on single-cavity multi-mode hybrid cavities

In this paper, a novel construction method for a single hybrid cavity is proposed for the first time, which integrates a quarter-mode substrate integrated waveguide structure into a patch cavity (QMSIWP), and a novel single-cavity multi-mode resonator is realized through the incorporation of cross-slot lines. A detailed analysis of its characteristics, combined with a specialized feed structure, leads to the design of multiple dual-band quasi-elliptic bandpass filters (BPFs) with varying frequency ratios and a triple-band quasi-elliptic BPF. The finite frequency transmission zeros (FTZs) and bandwidths (BWs) can be controlled by adjusting various parameters. For the demonstration, a triple-band quasi-elliptic BPF is fabricated and measured to validate the performance and design method of the proposed QMSIWP hybrid cavity and feed structure. The measured results agree with the synthesized and simulated results, confirming the proposed method's feasibility and universality. The proposed filter exhibits advantages such as compact size, high selectivity, and excellent group delay, which expands its application prospects and potential value.

Banks approved fraudulent loans to capture origination fees: evidence from the Paycheck Protection Program

Purpose The Small Business Administration (SBA) has estimated that a significant proportion of loans issued during the Paycheck Protection Program (PPP) were fraudulent. This paper aims to make strides to understand incentives that may have led to the approval of fraudulent loans. Design/methodology/approach The authors study the publicly available PPP loans data set, focusing on nonemployer businesses which make up about 51% of all loans. Because of the way businesses of this type were instructed to apply for loans, it is possible to deduce the monthly/annual profit each loan was claiming. Findings The authors find irregularities in the pattern of claimed profit by nonemployer businesses on PPP loans. There is a significant buildup of claimed profit just slightly under the threshold for the maximum loan claim, which does not align with estimates of average nonemployer business profitability. Research limitations/implications As it is not possible to verify individual business profits with publicly available data, the authors cannot identify or count loans, which are likely to be fraudulent. The focus on nonemployer businesses allows for the identification of reported profit, at the cost of eliminating most of the highest value loans from consideration. Practical implications Especially in areas with a high density of small banks, large numbers of potentially fraudulent loans were issued. In planning future disaster relief programs, the SBA must consider incentives, which led to fraudulent behavior during the PPP. Social implications Proponents of the PPP argue that it is impossible to completely eliminate fraudulent behavior due to the rapid nature by which the funds had to be distributed to avoid job loss. Nonetheless, the SBA estimates that up to 1/6 of the funding issued may have gone to fraudulent loans. Responsibility was placed on the banking system as regulators of the loans. However, the origination fee structure of the program, combined with limited liability to banks, may have produced adverse incentives. Originality/value Previous research on PPP fraud primarily identifies businesses and business owners as bad actors during the program. The authors argue that misuse of funds was not the only source of fraud during the program. Misrepresentation of business profits may have been widespread. Therefore, banks must have approved loans with misrepresented profit figures.

Broadband Filtering Antenna With Asymmetric Feeding Structure

ABSTRACTA compact highly selective broadband filter antenna with an asymmetric feed structure is proposed. The radiating patch of the antenna unit consists of a central elliptical patch and a pair of semi‐annular patches, and the antenna forms multiple coupling paths from the feed ports to the radiating patches to generate a radiation null (6.28 GHz), which achieves the roll‐off rate of 193 dB/GHz. The innovation of this design is that asymmetric L‐shaped branches of about half a wavelength are added on both sides of the microstrip feedline of the antenna to expand the operating bandwidth and generate a low‐frequency radiation null (4.66 GHz), which achieves the roll‐off rates of 164 dB/GHz. The simulated results show that impedance bandwidth is 23.8% (4.77–6.06 GHz) with the peak gain of 5.86 dBi, which size is 0.5λ0 × 0.5λ0 × 0.09λ0. Then, a 2 × 2 filtered antenna array is designed for experimental validation. The test results indicate that the impedance bandwidth of the antenna array is 21.5% (4.45–5.52 GHz), the in‐band gain is greater than 10 dBi and flat, and the out‐of‐band rejection level is greater than 20 dB. Attributed to the characteristics of easy and inexpensive manufacturing, the designed antenna has well application prospects in modern wireless communication systems.

Optimal investment-withdrawal strategy for variable annuities under a performance fee structure

Variable Annuities (VAs) provide policyholders with market participation while offering additional protection from insurers. In this article, we develop a mathematical model to explore the impact of different fee structures on VAs with a ratchet feature and derive analytical solutions to the associated optimal investment-withdrawal problem. We focus on a performance fee structure, highlighting its advantages over the traditional constant fee structure from both the insurer's and policyholder's perspectives. Our findings show that policyholders adopt more conservative investment strategies under the performance fee, leading to increased expected profits and reduced tail risks for risk-neutral insurers. From a mathematical standpoint, we contribute by proving the well-posedness of the associated free-boundary value problems (FBPs) and establishing verification theorems for the underlying control problems. These results involve non-standard analysis and estimations due to the ratchet feature and the guaranteed protections embedded in the contract.

Quad ports dielectric resonator antenna with simple feed network and high gain performance

This paper presents a quad-port multiple-input multiple-output (MIMO) single cylindrical dielectric resonator antenna (CDRA) for X-band applications. This approach is mainly based on selecting the proper feeding structure for each port as well as implanting vertical metallic vias (VMVs) to diminish the mutual coupling over a wide bandwidth. Two orthogonal apertures and two vertical probes are utilized as feeding structures to realize good isolation between all port combinations. For coupling mitigation between port1 and port2 that is due to the field distribution of the excited modes at these ports, four VMVs are inserted between them in appropriate positions to produce field orthogonality along wide bandwidth. The excited modes inside the proposed CDRA are HE52δ+2x,HE52δ+2y, HE32δ + 2, and TM12δ + 2. Isolation better than -15 dB is attained across the overlapping band of 340 MHz (4 %); from 8.2 to 8.54 GHz. Moreover, the proposed DRA provides a gain of 5.17, 7.21, 7.77, and 7.78 dBi for the four ports at 8.45 GHz and the total efficiencies at all ports are from 65 to 85 % across the operating band. The MIMO performance of the proposed design shows a good envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), channel capacity loss (CCL) and mean effective gain (MEG) through the whole band for all ports.

Long-term survival of asexual Zymoseptoria tritici spores in the environment

BackgroundThe fungal phytopathogen Zymoseptoria tritici, causal agent of the economically damaging Septoria tritici blotch of wheat, is different from most foliar fungal pathogens in that its germination occurs slowly and apparently randomly after arrival on the leaf surface and is followed by a potentially prolonged period of epiphytic growth and even reproduction, during which no feeding structures are formed by the fungus. Thus, understanding the cues for germination and the mechanisms that underpin survival in low-nutrient environments could provide key new avenues for disease control.ResultsIn this work, we examine survival, culturability and virulence of spores following transfer from a high nutrient environment to water. We find that a sub-population of Z. tritici spores can survive and remain virulent for at least 7 weeks in water alone, during which time multicellular structures split to single cells. The fungus relies heavily on stored lipids; however, if cell suspensions in water are dried, the cells survive without lipid utilisation. Changes in gene expression in the first hours after suspension in water reflect adaptation to stress, while longer term starvation (7 days) induces changes particularly in primary metabolism and cytochrome P450 (CYP) gene expression. Importantly, we also found that Z. tritici spores are equally or better able to survive in soil as in water, and that rain-splash occurring 49 days after soil inoculation can transfer cells to wheat seedlings growing in inoculated soil and cause Septoria leaf blotch disease.ConclusionsZ. tritici blastospores can survive in water or soil for long periods, potentially spanning the intercrop period for UK winter wheat. They rely on internal lipid stores, with no external nutrition, and although a large proportion of spores do not survive for such an extended period, those that do remain as virulent as spores grown on rich media. Thus, Z. tritici has exceptional survival strategies, which are likely to be important in understanding its population genetics and in developing novel routes for Septoria leaf blotch control.

A wideband circularly-polarized MIMO filtering array antenna using dual-layer circular patch

ABSTRACT A novel wideband circularly-polarized (CP) MIMO filtering array antenna with dual-layer circular cross-slotted patch is introduced. The presented element consists of a two-way feeding structure designed with equal amplitude and 90° phase difference, and a dual-layer circular cross-slotted patch structure. An aperture-couple-driven patch is positioned between a cross-slotted patch and a dual-feed structure. It facilitates magnetic coupling to achieve a high-frequency resonant mode and radiation null. Meanwhile, four arc-shaped patches are electrically coupled to the driver patch by surrounding it with four shorting vias to improve the bandwidth. In multiple-input multiple-output (MIMO) wireless systems, a two-port MIMO dual-CP filtering array antenna for the Sub-6 G band is proposed. The design utilizes four proposed CP antenna elements and a dual-port transmission structure. The dual-port transmission structure consists of two sets of T-junction power dividers that are 180° phase shifted with opposite polarization. The dual-CP MIMO filtering array antenna of the impedance bandwidth is 21.8% (3.1 ~ 3.9 GHz). The AR bandwidth is 13.1% (3.3 ~ 3.7 GHz), while the gain bandwidth is 20.1%. Additionally, the isolation between the antenna elements is less than −15.0 dB. The envelope correlation coefficient between its two ports is less than 0.02.

A versatile conformal circularly polarized quad-element antenna for X-band applications

This article presents a flexible four-element antenna for X-band applications. The proposed antenna covers the spectrum ranging from 10.6 to 11.9 GHz, including a significant portion of the X-band. The single antenna element comprises a modified E-shaped radiating patch, which is fed by a unique feeding structure consisting of a 50-Ω feeding strip connected with two rectangular stubs on both sides. All antenna elements are printed on a flexible felt 60 mm × 60 mm × 1 mm (2.12 λ × 2.12 λ × 0.035 λ at 10.6 GHz) substrate. The proposed antenna exhibits circular polarization over the desired bans of operation with an axial ratio (< 3 dB) bandwidth of 1.2 GHz, which is significant for X-band applications. The designed antenna is manufactured and practically tested. Both simulated and measured results agree well with each other, ensuring the optimal performance of the antenna. Moreover, the antenna achieves a maximum gain of up to 8 dBi in the desired band of operation. Further MIMO parameters, including envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), and mean effective gain (MEG), are calculated to validate the MIMO performance. Finally, a conformal analysis was carried out to study the robustness of the antenna in various bending scenarios. Results show that the antenna reported in this article is the correct choice for conformal X-band MIMO applications.

Mandible composition and properties in two selected praying mantises (Insecta, Mantodea).

Insects process their food with their cuticle-based mouthparts. These feeding structures reflect their diversity and can, in some cases, showcase adaptations in material composition, mechanical properties, and shape to suit their specific dietary preferences. To pave the way to deeply understand the interaction between mouthparts and food and to determine potential adaptations of the structures to the food, this study focuses on the mandibles of two praying mantis species. Gongylus gongylodes feeds mainly on Diptera, and Sphodromantis lineola forages on larger prey. Employing scanning electron microscopy, the mandibular morphologies were analyzed. The degree of the cuticle tanning was tested using confocal laser scanning microscopy. Furthermore, the contents of transition and alkaline earth metals in the mandible cuticle were studied using energy-dispersive X-ray spectroscopy and the mechanical properties tested by nanoindentation. We found that S. lineola mandibles show pronounced gradients of Young's modulus and hardness from the basis to the tip, which might be an adaptation against high stresses during biting and chewing. G. gongylodes, in contrast, did not show pronounced gradients, which may indicate that there is less stress involved in feeding-necessary to test in future studies. The mechanical properties of manidibles in both species are related to the degree of cuticle tanning but also positively correlate with the content of magnesium. These findings enrich our understanding of insect cuticle biology but also present new sets of data on praying mantis structures.

Feeding strategies and habits of the coral guard‐crab Trapezia bidentata

AbstractThe crab Trapezia bidentata is a conspicuous crustacean characterized as an obligate symbiont with branching corals, such as species of Pocillopora. These crustaceans have been identified as strict corallivores with a feeding dependency on the mucus excreted by adult colonies in the genus Pocillopora. However, like other crustaceans, individuals of T. bidentata have a nutritional plasticity that has not been described. We used an integrative approach, including traditional taxonomy and high‐throughput sequencing of hypervariable region V9 of the 18S rRNA gene, to describe the mouthparts and the diet of individuals of Trapezia bidentata associated with adult colonies of Pocillopora verrucosa. The presence of setae on the ambulatory dactylus and maxillipeds, forming food brushes and combs, was evident. Sequencing and analyses of the intestinal content of the crustaceans found evidence of 18 phyla, mostly represented by Brachiopoda (28.1%), Arthropoda (31.7%), and Cnidaria (21.1%), but also small contributions (≤2%) of other animal groups such as Mollusca, Annelida, and Tunicata. In addition, a few traces (≤0.5%) of algae and fungi were identified. The feeding structures and intestinal content showed that individuals of T. bidentata are omnivorous and behave as suspension feeders and scrapers, obtaining nourishment from tissues transported in the water column and in the mucus and tissue of P. verrucosa. The results provide a clearer characterization of the role of T. bidentata, which is a crucial guard crustacean associated with P. verrucosa. We found both corallivorous and suspension‐feeding habits, which demonstrates feeding plasticity, a positive characteristic for the survival of the species.

Generalized Deterministic Automated Design of Metasurface Antennas With 3-D Feeding Structures

Generalized Deterministic Automated Design of Metasurface Antennas With 3-D Feeding Structures

Does maker-taker limit order subsidy improve market outcomes? Quasi-natural experimental evidence

We provide a new theory of exchange access fees that explains why fees relatively reduce the probability of execution and increase the limit order queue length on “maker-taker” platforms. Nonetheless, the limit order subsidy greatly improves market depth, together with market efficiency and trading volume. Moreover, fee structures never “wash out” regardless of the minimum tick. The regulatory requirement that trading and order flow depend only on raw (nominal) spreads and prices underpins the multi-billion-dollar subsidy to limit orders. So long as a platform remains competitive, elimination of the fee structure does not alter the raw spread, but it does lower the cum fee spread. We test these implications with a unilateral maker-taker fee/rebate reduction using NASDAQ's “quasi-natural” $1.9 trillion experiment to find support for our theory.

Utility Cut Impact Assessment and Fee Development Using Pavement Management System

The purpose of this study is to estimate any damage caused by utility cuts to pavements and develop a fee schedule to recover the costs associated with such damage using the City of Pacifica, CA, U.S.’s pavement management system (PMS). To accomplish this, the study looked at the functional deterioration of pavements resulting from utility cuts. The City of Pacifica’s PMS containing a vast dataset of pavement distress spanning 15 years, comprising thousands of data points encompassing various pavement ages and conditions, was analyzed to assess the impact of utility cuts. The findings from this study include: 1) Pavements with cuts of any size deteriorate more than pavements without cuts across all age groups with one exception for older residentials with small cuts; 2) On average, pavement condition index drops by 30% if the cut area is greater than 10% of the section area; and 3) Utility cuts inflict greater damage on newer pavements (&lt;10 years old) compared with older ones (≥10 years old). Consequently, new pavements experience an average percent reduction of approximately 33% in their remaining service life, while older pavements suffer a reduction of about 17%. The statistical analyses indicate that utility cuts caused significant damage, and supported a tiered utility cut fee structure based on functional classification, age of pavement, and size of the cut. The resulting fee schedule is based on 2021 material and construction cost estimates; consequently, implementation including an annual adjustment for inflation is recommended. Example fee calculations are provided.