bluuebunny/crossref_metadata_2025_split huggingface dataset:
Filter mesh size of cladocerans predicts retention efficiency for bacteria
Authors: Brendelberger Heinz 
Published: April 2010

This study tested the hypothesis that filter mesh size can predict retention efficiency of very small particles by cladocerans. Morphology of the filtering apparatus and size distribution of the food particles were measured by scanning electron microscopy. From these morphological data the retention of food particles could be predicted for individual animals. Short‐term, dual‐label experiments were used to measure the uptake of small food particles by four species of Cladocera (Daphnia magna, Daphnia pulex, Simocephalus vetulus, and Diaphanosoma brachyurum). The green alga Scenedesmus acutus was paired with each of six classes of small particles; three size fractions of free‐living planktonic bacteria, two cyanobacterial species of different sizes, and the green alga Stichococcus minutissima were fed. The clearance rates for these very small particles were divided by the clearance rate for Scenedesmus to calculate retention efficiencies.Retention efficiencies were between 33 and 154%. Cladoceran species with coarser filtering meshes showed lower retention efficiencies for bacteria and cyanobacteria. Within species, both predicted and observed retention efficiencies were greater for juveniles than for adults. Although collection mechanisms other than sieving probably operate, the size distribution of particles collected by cladocerans is closely predicted by the size‐frequency distribution of meshes of the thoracic feeding limbs.
An expatriate red tide bloom: Transport, distribution, and persistence
Authors: Tester Patricia A. , Stumpf Richard P. , Vukovich Fred M. , Fowler Patricia K. , Turner Jeflerson T. 
Published: April 2010

In November 1987, the toxic dinoflagellate Gymnodinium breve bloomed in North Carolina nearshore waters. This occur rence was the first record of G. breve north of Florida, a range extension of >800 km. We propose the (Gulf of Mexico) Loop Current‐Florida Current‐Gulf Stream system as the transport mechanism for G. breve cells from a late summer bloom off the southwest coast of Florida (Charlotte Harbor‐Sarasota). The estimated transit time for cells around the peninsula and northward to the continental shelf off North Carolina is 22–54 d.About 30 d after the Charlotte Harbor‐Sarasota bloom, satellite images of sea‐surface temperature substantiated the shoreward movement of a filament of Gulf Stream water onto the narrow continental shelf between Cape Hatteras and Cape Lookout. This filament, the likely source of G. breve cells, remained in nearshore waters and was identifiable in satellite images for >19 d. Once the bloom was inshore, both windspeed and direction were important in determining its distribution.
Diagenesis of belowground biomass of Spartina alterniflora in salt‐marsh sediments
Authors: Benner Ronald , Fogel Marilyn L. , Sprague E. Kent 
Published: April 2010

Belowground biomass of Spartina alterniflora lost 55% of its organic matter during 18 months of decomposition in salt‐marsh sediments. Significant losses of lignin were observed under highly reducing conditions confirming previous reports of lignin degradation in the absence of molecular oxygen. The submolecular components of lignin varied in susceptibility to degradation and were ranked in the following descending order of resistance to decomposition: V∼P>S∼C. The preferential degradation of the cinnamyl and syringyl components constrains the quantitative usefulness of these compounds for estimating the contributions of herbaceous and angiosperm tissues to pools of dissolved and particulate organic matter. The relative concentration of lignin increased about 1.6‐fold during decomposition owing to the more rapid loss of polysaccharides.Two phases in nitrogen dynamics were evident during the decomposition study. During the first 4 months of decomposition there was a net loss of N from Spartina tissues at a rate of about 10 N g‒1 tissue d‒1. After this initial phase of net N loss, a phase of N immobilization was evident and was tightly coupled with rates of microbial degradation of the tissues. Net rates of N immobilization were ∼ 19 µg N g‒1 tissue d‒1; by the end of the 18‐month study more N had accumulated in the tissues than was initially present. Stable N isotope compositions of decaying Spartina were also very dynamic and reflected the sources of N that were immobilized during decomposition and the N transformations that occurred on the detrital particles.The stable C isotope composition of the polysaccharide components of Spartina was ∼6‰ heavier than that of the lignin component. The isotopic compositions of these components retained the 6‰ difference throughout the 18‐month study. The stable C isotope composition of the bulk tissues, however, decreased gradually during decomposition as the isotopically heavier polysaccharides were preferentially lost. Residual material was relatively enriched in the isotopically lighter, lignin‐derived C.
Population dynamics and body‐size selection in Daphnia
Authors: Tessier Alan J. , Young Andrew , Leibold Mathew 
Published: April 2010

We examined the population dynamics and seasonal change in body size of a population of Daphnia galeata mendotae experiencing strong vertebrate predation. The intensity of food limitation was quantified seasonally by in situ food addition. We also collected live animals early and late in the summer for laboratory studies designed to estimate genetic variation and seasonal change in life‐history traits for the population.The population was characterized by nearly equal short‐term birth and death rates that were strongly correlated with population density, suggesting density dependence. The population generally exhibited very high birth and death rates and no significant response to experimental food addition. The one exception was June 1988, when the population achieved high densities and exhibited strong food limitation. Throughout both summers, minimal and average body sizes of adults decreased.Laboratory studies document substantial genetic variation for body size and other life‐history traits among animals collected early in summer. By late summer, however, there was little genetic variation for these same traits. Furthermore, clones collected early in summer were genetically larger in body size at birth and maturity than clones collected in late summer. We interpret these results as indicating natural selection for body size.
Estimating the impact of fungal parasites on phytoplankton populations
Authors: Bruning Kees , Lingeman Rob , Ringelberg Joop 
Published: April 2010

A population‐dynamic model is formulated to estimate the impact of chytrid and related fungal parasites on phytoplankton populations. The specific loss rate of uninfected host cells due to infection is used as a measure of the impact. Calculating this loss rate requires information about four parameters: prevalence of infection (i.e. the proportion of the host cells infected), development time of the sporangia of the parasite, specific growth rate of the uninfected host, and difference between loss rates of infected and uninfected host cells due to loss factors other than parasitism. When only cell counts of the host population are available instead of growth and loss rate values, the model can be used to calculate a minimum estimate of the impact of the parasite. The impact of the parasite at a given prevalence of infection can vary considerably as a consequence of environmental effects on the latter three parameters. Therefore, prevalence is not a good parameter to judge the severity of fungal epidemics. A phytoplankton population starts to decline when prevalence exceeds a certain threshold value. This critical prevalence of infection can be calculated with the model and is also highly dependent on external conditions.The model is applied to epidemics of the chytrid Rhizophydium planktonicum Canter emend. in a population of the diatom Asterionella formosa Hass. in Lake Maarsseveen 1. The end of both the spring and summer 1984 bloom of the diatom was caused by epidemics of the chytrid. Model results suggested also that higher sinking rates, caused by an increasing proportion of dead cells in the colonies, resulted in an additional loss factor due to parasitism for this colonial diatom.
Temporal variations of 234Th activity in the water column of Dabob Bay: Particle scavenging
Authors: Wei Ching-Ling , Murray James W. 
Published: April 2010

Monthly measurements of total, dissolved, and particulate 234Th, along with fluxes of total mass and particulate 234Th, were made throughout 1987 in Dabob Bay, Washington. Vertical distributions of total 234Th showed a large deficiency relative to 278U throughout the water column during all sampling periods.Total 234Th activities in surface waters were generally higher in winter and lower in summer, in response to seasonal biological activity. In spite of this variation, the steady state assumption seems valid for modeling 234Th of the bay because the magnitude of variation is insignificant in the mass balance calculation. The range of residence times of total, dissolved, and particulate 234Th estimated from an irreversible scavenging model are 4–70, < 1–10, and 3–60 d, respectively. The residence time of 234Th is controlled by the suspended particles whose distribution is determined by biological production in the surface layer and resuspension of bottom sediments.Vertical fluxes of 214Th measured by sediment traps also showed wide seasonal variation and generally increased monotonically from 200–1,000 dpm m‒2 d‒1 at 20 m to 2,000–4,000 at 100 m. The flux of 234Th predicted with the steady state scavenging model tends to be about twice the directly measured 234Th flux. This difference may be due either to low trap efficiency for 234Th‐containing particles or to boundary scavenging at the sides of the basin. The residence times of particulate 234Th and total suspended matter agree well, and both are influenced by biological processes.
Body size and egg production in the marine copepod Acartia hudsonica during a winter‐spring diatom bloom in Narragansett Bay
Authors: Durbin Edward G. , Durbin Ann G. , Campbell Robert G. 
Published: April 2010

Seasonal changes in size and egg production in the copepod Acartia hudsonica were investigated during the 1984 winter–spring bloom in Narragansett. Bay. Possible food limitation was investigated through comparisons of short‐term weight change and egg production rate in copepods incubated in ambient Narragansett Bay water and in bay water enriched with cultured algae. A preliminary experiment showed that egg production responded in <24 h to a change in food availability at 4°C—the coldest experimental temperature. Food was not limiting in February–April, but mild food limitation developed in May–June, affecting body weight more than egg production. These results contrast with strong food limitation of the summer dominant, Acartia tonsa. Empirical regressions describe relationships between A. hudsonica length and weight, and egg production in relation to temperature, weight, and field Chl a.A separate study suggested that A. hudsonica adults were dominated by changing age groups during the winter–spring period. Present results indicate that the adult age distribution affects mean body weight, condition factor, and egg production rate, especially in April and May when the autumn‐hatched, overwintering copepods are being replaced by newly matured, winter–spring hatched adults.
Effects of temperature and food abundance on grazing and short‐term weight change in the marine copepod Acartia hudsonica
Authors: Durbin Edward G. , Durbin Ann G. 
Published: April 2010

Ingestion and short‐term weight change in adult female Acartia hudsonica were investigated at 4.5°, 8°, 12°, and 16°C with the solitary diatom Thalassiosira constricta as food. Narragansett Bay copepods were preadapted to the desired temperature and saturating food level for 3 d to standardize feeding history before the experiments. Maximal ingestion rates at the four temperatures were 16,460, 14,120, 21,470, and 29,960 cells copepod‒1d‒1 or 43.9, 37.2, 67.9, and 92.9% body C(Q10 = 2.3) and 34.2, 30.7, 42.6, and 74.7% body N d‒1 (Q10 = 2.4). The critical concentration varied between 840 and 1,900 cells ml‒1 (0.17–0.23 µg C ml‒1) and was not significantly related to temperature. Maximal clearance rate was similar at all temperatures (20.8–23.9 ml copepod‒1d‒1), but on a weight‐specific basis increased from 3.3 to 6.0 ml (µg copepod C)‒1d‒1 between 4.5° and 16°C (Q10 = 1.8). Feeding rates at 4.5° and 8°C were similar; the seemingly low ingestion rates at 8°C were interpreted as evidence for a senescent population of adult copepods in the bay from late April to early May.During preadaptation at high food, A. hudsonica body C and N either stayed constant (indicating saturating food in the field) or increased (indicating food limitation in situ). Body weight was sensitive to variation in food supply; during the 24‐h feeding experiments weight remained stable at the two highest food levels, but declined significantly at lower levels. Maximal observed weight loss was temperature‐dependent, increasing from ∼ 15% C and 12% N d‒1 at 4.5°C to 25% C and 17% N d‒1 at 16°C.
Seasonal changes in size frequency distribution and estimated age in the marine copepod Acartia hudsonica during a winter‐spring diatom bloom in Narragansett Bay
Authors: Durbin Ann G. , Durbin Edward G. 
Published: April 2010

Seasonal changes in length frequency and estimated age distributions indicated that Acartia hudsonica adult females are dominated by successive age groups during the winter–spring bloom in Narragansett Bay. The biomass peak during March and April was composed of over‐wintering, late autumn‐spawned copepods. Winter‐spawned copepods entered the adult population during a brief period in late April to early May, and the influx of spring‐spawned copepods began during the second week of May. Concurrent studies of egg production and feeding suggested senescence of the adult population prior to the transition between the autumn‐spawned and the winter–spring‐spawned copepods. Thus population productivity may reflect not only environmental conditions, but also the age‐dependent physiological condition of the adults.Modeling indicated that small interannual variations in temperature (±1°C) will significantly affect development rate and maturation of A. hudsonica during winter and spring. The 2°C temperature range corresponded to a 3‐week shift in the timing of peak maturation and could significantly alter the intensity of grazing and degree of coupling between primary producers and herbivores during the spring bloom.
Internal pressurization and convective gas flow in some emergent freshwater macrophytes
Authors: Brix Hans , Sorrell> Brian K. , Orr Philip T. 
Published: April 2010

Internal pressurization and convective through‐flow are demonstrated to be common attributes of wetland plants with cylindrical culms or linear leaves. Eight of 14 species tested produced static internal gas pressure differentials of 200–1,300 Pa relative to ambient and internal convective airflows of 0.2 to >10 cm3 min−1 culm−1, depending on species. Four species produced internal static pressure differentials of <100 Pa. Two species did not pressurize. The driving forces are gradients in temperature and water vapor between the internal gas spaces of the plants and the ambient atmosphere (thermal transpiration and humidity‐induced pressurization).A clear diel variation in pressurization and convective flow was observed; rates were highest in the afternoon and lowest at night, responding to ambient changes in light, temperature, and humidity. The resistance to airflow at the stem‐rhizome junction was very high for some species, resulting in a low ability to convert internal pressurization into convective airflow through the rhizomes. Species with a high potential for internal pressurization and a low internal resistance to convective flow seem to have a competitive advantage over species that rely exclusively on diffusive gas transport, which allows them to grow in deeper waters.
DenseNet model incorporating hybrid attention mechanisms and clinical features for pancreatic cystic tumor classification
Authors: Tian Hui , Zhang Bo , Zhang Zhiwei , Xu Zhenshun , Jin Liang , Bian Yun , Wu Jie 
Published: May 2024

AbstractPurposeThe aim of this study is to develop a deep learning model capable of discriminating between pancreatic plasma cystic neoplasms (SCN) and mucinous cystic neoplasms (MCN) by leveraging patient‐specific clinical features and imaging outcomes. The intent is to offer valuable diagnostic support to clinicians in their clinical decision‐making processes.MethodsThe construction of the deep learning model involved utilizing a dataset comprising abdominal magnetic resonance T2‐weighted images obtained from patients diagnosed with pancreatic cystic tumors at Changhai Hospital. The dataset comprised 207 patients with SCN and 93 patients with MCN, encompassing a total of 1761 images. The foundational architecture employed was DenseNet‐161, augmented with a hybrid attention mechanism module. This integration aimed to enhance the network's attentiveness toward channel and spatial features, thereby amplifying its performance. Additionally, clinical features were incorporated prior to the fully connected layer of the network to actively contribute to subsequent decision‐making processes, thereby significantly augmenting the model's classification accuracy. The final patient classification outcomes were derived using a joint voting methodology, and the model underwent comprehensive evaluation.ResultsUsing the five‐fold cross validation, the accuracy of the classification model in this paper was 92.44%, with an AUC value of 0.971, a precision rate of 0.956, a recall rate of 0.919, a specificity of 0.933, and an F1‐score of 0.936.ConclusionThis study demonstrates that the DenseNet model, which incorporates hybrid attention mechanisms and clinical features, is effective for distinguishing between SCN and MCN, and has potential application for the diagnosis of pancreatic cystic tumors in clinical practice.
Point Defects in Hexagonal SiP Monolayer: A Systematic Investigation on the Electronic and Magnetic Properties
Authors: Ha Chu Viet , Ponce‐Pérez R , Guerrero‐Sanchez J. , Hoat D. M. 
Published: May 2024

AbstractIn this work, point defects are proposed to modify the electronic and magnetic properties of SiP monolayer. Pristine monolayer is a non‐magnetic semiconductor 2D material with energy gap of 1.52(2.21) eV as predicted by PBE(HSE06) functional. Single Si vacancy (), Si+P divacancy (), and substituting one P atom by one Si atom () magnetize significantly SiP monolayer. Herein, total magnetic moments between 1.00 and 2.00 are obtained . In contrast, no magnetism is induced by single P vacancy (), substituting one Si atom by one P atom (), and exchanging pair Si‐P positions (). Moreover, significant magnetization of SiP monolayer is also achieved by doping with single Li and Cu atoms ( and ), as well as pair of Li and Cu atoms ( and ). Total magnetic moments between 0.84 and 1.42 are obtained. Interestingly, the half‐metallicity is observed in and systems. When substituting P atom, F, Cl, and Br impurities reduce significantly the SiP monolayer bandgap, preserving its non‐magnetic nature. In contrast, a total magnetic moment of 1.26 is obtained by doping with I atom. Results presented herein may introduce the defected and doped SiP systems as prospective 2D candidates for spintronic and optoelectronic applications.
Record‐High Thermoelectric Performance in Al‐Doped ZnO via Anderson Localization of Band Edge States
Authors: Serhiienko Illia , Novitskii Andrei , Garmroudi Fabian , Kolesnikov Evgeny , Chernyshova Evgenia , Sviridova Tatyana , Bogach Aleksei , Voronin Andrei , Nguyen Hieu Duy , Kawamoto Naoyuki , Bauer Ernst , Khovaylo Vladimir , Mori Takao 
Published: May 2024

AbstractOxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics ( 21.5 µW cm−1 K−2 and 0.5 at 1100 K in ) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics.
Restoration Temperature Control through Glass Transition Temperature Modulation of Shape Memory Polymer for Thermally Switchable Adhesive
Authors: Park Han Jun , Kim Minsu , Lee Jihoon , Kwak Moon Kyu 
Published: May 2024

AbstractShape memory polymers (SMPs) undergo changes between arbitrary shapes and programmed shapes upon exposure to specific stimulus, allowing them to restore their original shape. All kinds of external stimuli have a threshold to change the shape of the SMP. Especially, for the thermal type SMP, the critical temperature for shape restoration is typically near the glass transition temperature (Tg). In this study, the controllability of the restoration temperature is analyzed by adjusting the Tg of the polymer using Norland Optical Adhesive 63, which can be cured with UV irradiation. By varying the ambient temperature from 20 to 120 °C during UV exposure, Tg changes ranging from 35.84 to 50.50 °C are obtained, with corresponding changes in restoration temperature. As a practical application, a thermal‐activated SMP dry adhesive is developed with programmable Tg and switchable adhesion. The fabricated SMP dry adhesive exhibited strong adhesion to substrates with various surface roughness. Additionally, the shape memory effect allowed for easy detachment through shape recovery, and different adhesive performances at different temperatures are achieved by programming various Tg values. Moreover, the simple manufacturing process of the SMP dry adhesive is confirmed to be suitable for continuous fabrication processes based on roll‐to‐roll methods.
Reversible Snapping of Constrained Anisotropic Hydrogels Upon Light Stimulations
Authors: Dai Chen Fei , Zhu Qing Li , Khoruzhenko Olena , Thelen Michael , Bai Huiying , Breu Josef , Du Miao , Zheng Qiang , Wu Zi Liang 
Published: May 2024

AbstractCreatures, such as Venus flytrap and hummingbirds, capable of rapid predation through snap‐through transition, provide paradigms for the design of soft actuators and robots with fast actions. However, these artificial “snappers” usually need contact stimulations to trigger the flipping. Reported here is a constrained anisotropic poly(N‐isopropylacrylamide) hydrogel showing fast snapping upon light stimulation. This hydrogel is prepared by flow‐induced orientation of nanosheets (NSs) within a rectangular tube. The precursor containing gold nanoparticles is immediately exposed to UV light for photopolymerization to fix the ordered structure of NSs. Two ends of the slender gel are clamped to form a buckle with bistability nature, which snaps to the other side upon laser irradiation. Systematic experiments are conducted to investigate the influences of power intensity and irradiation angle of the laser, as well as thickness and buckle height of the gel, on the snapping behaviors. The fast snapping is further used to kick a plastic bead and control the switch state. Furthermore, synergetic or oscillated snapping of the gel with two buckles of opposite directions is realized by inclined irradiation of a laser or horizontal irradiation with two lasers, respectively. Such light‐steered snapping of hydrogels should merit designing soft robots, energy harvests, etc.