bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequencies of FoxP3+ naïve T cells are related to both viral load and naïve T cell proliferation responses in HIV disease
Authors: Rodriguez Benigno , Bazdar Douglas A , Funderburg Nicholas , Asaad Robert , Luciano Angel A , Yadavalli Gopal , Kalayjian Robert C , Lederman Michael M , Sieg Scott F 
Published: June 2011

ABSTRACTHIV infection results in depletion and dysfunction of naïve CD4+ T cells. The mechanisms underlying these deficiencies are not understood. We investigated the frequencies of CD4+ naïve subsets in HIV disease as defined by expression of CD25 and/or FoxP3 and the relationship of these frequencies to naïve T cell proliferation function. We observed increased proportions of CD25+FoxP3+ and CD25+FoxP3– cells and decreased proportions of CD25–FoxP3– cells within the naïve CD4+ cell compartment from HIV-infected persons compared with findings in healthy donors. These perturbations were related to higher plasma HIV RNA levels but not with higher immune activation, as measured by the proportions of CD38+ memory CD4+ T cells. Naïve T cell proliferation responses to mitogen stimulation were inversely related to the frequencies and absolute numbers of FoxP3+ naïve T cells. MDA, a marker of oxidative stress, and sCD14, a marker of monocyte activation and a surrogate for microbial translocation, were increased in serum samples from HIV+ donors; however, neither marker was related to naïve T cell function in HIV+ donors. These observations suggest that alterations in naïve T cell subset frequencies could contribute to naïve T cell dysfunction in HIV disease, but these alterations are not necessarily the result of chronic immune activation.
Dive behaviour impacts the ability of heart rate to predict oxygen consumption in Steller sea lions (Eumetopias jubatus) foraging at depth
Authors: Young Beth L. , Rosen David A. S. , Hindle Allyson G. , Haulena Martin , Trites Andrew W. 
Published: June 2011

SUMMARYThe predictive relationship between heart rate (fH) and oxygen consumption () has been derived for several species of marine mammals swimming horizontally or diving in tanks to shallow depths. However, it is unclear how dive activity affects the relationship and whether the existing equations apply to animals diving to deeper depths. We investigated these questions by simultaneously measuring the fH and of Steller sea lions (Eumetopias jubatus) under different activity states (surface resting or diving), types of dives (single dives or dive bouts), and depths (10 or 40 m). We examined the relationship over dives only and also over dive cycles (dive + surface interval). We found that fH could only predict over a complete single dive cycle or dive bout cycle (i.e. surface intervals had to be included). The predictive equation derived for sea lions resting on the surface did not differ from that for single dive cycles. However, the equation derived over dive bout cycles (multiple dives + surface intervals) differed from those for single dive cycles or surface resting, with similar fH for multiple dive bout equations yielding higher predicted than that for single dive bout cycles (or resting). The relationships were not significantly affected by dive duration, dive depth, water temperature or cumulative food consumed under the conditions tested. Ultimately, our results demonstrate that fH can be used to predict activity-specific metabolic rates of diving Steller sea lions, but only over complete dive cycles that include a post-dive surface recovery period.
Honeybee flight: a novel ‘streamlining’ response
Authors: Luu Tien , Cheung Allen , Ball David , Srinivasan Mandyam V. 
Published: June 2011

SUMMARYAnimals that move rapidly through the air can save considerable energy by reducing the drag that they need to overcome during flight. We describe a novel ‘streamlining’ response in tethered, flying honeybees in which the abdomen is held in a raised position when the visual system is exposed to a pattern of image motion that is characteristic of forward flight. This visually evoked response, which can be elicited without exposing the insect to any airflow, presumably serves to reduce the aerodynamic drag that would otherwise be produced by the abdomen during real flight. The response is critically dependent on the presence of appropriate image motion everywhere within the large field of view of the insect. Thus, our results also underscore the importance of using panoramic stimulation for the study of visually guided flight in insects, and reveal the relative importance of various regions of the visual field in assessing the speed of flight through the environment.
Renal responses to salinity change in snakes with and without salt glands
Authors: Babonis Leslie S. , Miller Stephanie N. , Evans David H. 
Published: June 2011

SUMMARY
To understand renal responses to salinity change in aquatic reptiles, we examined the structure and function of the kidney in three species of snake: a marine species with a salt gland (Laticauda semifasciata), a marine species without a salt gland (Nerodia clarkii clarkii) and a freshwater species without a salt gland (Nerodia fasciata). Both marine species maintained relatively constant plasma ions, even after acclimation to saltwater. By contrast, both plasma Cl– and mortality increased with salinity in the freshwater species. To investigate putative renal ion regulatory mechanisms, we examined the distribution and abundance of Na+/K+-ATPase (NKA) and the Na+/K+/2Cl– cotransporter (NKCC2). In all species, NKA localized to the basolateral membranes of the distal tubule and the connecting segments and collecting ducts only; there was no effect of salinity on the distribution of NKA or on the abundance of NKA mRNA in any species. NKCC2 protein was undetectable in the kidney of any of the species and there was no effect of salinity on NKCC2 mRNA abundance. We also examined the distribution and abundance of aquaporin 3 (AQP3) in the kidney of these species; although putative AQP3 localized to the basolateral membranes of the connecting segments and collecting ducts of all three species, there was no effect of salinity on the localization of the protein or the abundance of the transcript. Interestingly, we found very few differences across species, suggesting that the snake kidney may play a trivial role in limiting habitat use.
Effects of shell morphology on mechanics of zebra and quagga mussel locomotion
Authors: Peyer Suzanne M. , Hermanson John C. , Lee Carol Eunmi 
Published: June 2011

SUMMARYAlthough zebra mussels (Dreissena polymorpha) initially colonized shallow habitats within the North American Great Lakes, quagga mussels (Dreissena bugensis) are becoming dominant in both shallow- and deep-water habitats. Shell morphology differs among zebra, shallow quagga and deep quagga mussels but functional consequences of such differences are unknown. We examined effects of shell morphology on locomotion for the three morphotypes on hard (typical of shallow habitats) and soft (characteristic of deep habitats) sedimentary substrates. We quantified morphology using the polar moment of inertia, a parameter used in calculating kinetic energy that describes shell area distribution and resistance to rotation. We quantified mussel locomotion by determining the ratio of rotational (Krot) to translational kinetic energy (Ktrans). On hard substrate, Krot:Ktrans of deep quagga mussels was fourfold greater than for the other morphotypes, indicating greater energy expenditure in rotation relative to translation. On soft substrate, Krot:Ktrans of deep quagga mussels was approximately one-third of that on hard substrate, indicating lower energy expenditure in rotation on soft substrate. Overall, our study demonstrates that shell morphology correlates with differences in locomotion (i.e. Krot:Ktrans) among morphotypes. Although deep quagga mussels were similar to zebra and shallow quagga mussels in terms of energy expenditure on sedimentary substrate, their morphology was energetically maladaptive for linear movement on hard substrate. As quagga mussels can possess two distinct morphotypes (i.e. shallow and deep morphs), they might more effectively utilize a broader range of substrates than zebra mussels, potentially enhancing their ability to colonize a wider range of habitats.
Hypothalamic neuropeptides, not leptin sensitivity, contributes to the hyperphagia in lactating Brandt's voles, Lasiopodomys brandtii
Authors: Cui Jian-Guo , Tang Gang-Bing , Wang De-Hua 
Published: June 2011

SUMMARY
Both pregnancy and lactation are associated with hyperphagia, and circulating leptin levels are elevated during pregnancy but decreased during lactation in Brandt's voles, Lasiopodomys brandtii. Previous findings suggest that impaired leptin sensitivity contributes to hyperphagia during pregnancy. The present study aimed to examine whether the decreased circulating leptin level and/or hypothalamic leptin sensitivity contributed to the hyperphagia during lactation in Brandt's voles. The serum leptin level and mRNA expression of the long form of the leptin receptor (Ob-Rb), suppressor-of-cytokine-signalling-3 (SOCS-3), neuropeptide Y (NPY), agouti-related protein (AgRP), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus were examined on dioestrous, day 5, day 17 of lactation and day 27 (1 week after weaning) in Brandt's voles. Compared with controls, hypothalamic Ob-Rb and SOCS-3 mRNA expression was not significantly changed during lactation. The serum leptin level was significantly lower in lactating females than in the non-reproductive group. Hypothalamic NPY and AgRP mRNA expression significantly increased whereas POMC mRNA expression was significantly decreased during lactation compared with controls. However, there were no significant changes in hypothalamic CART mRNA expression. Food intake was positively correlated with NPY and AgRP mRNA expression but negatively correlated with POMC mRNA expression during lactation. These data suggest that hyperphagia during lactation was associated with low leptin levels, but not impaired leptin sensitivity, and that the hypothalamic neuropeptides NPY, AgRP and POMC are involved in mediating the role of leptin in food intake regulation in lactating Brandt's voles.
Constraints on the adhesion of viscous threads spun by orb-weaving spiders: the tensile strength of glycoprotein glue exceeds its adhesion
Authors: Opell Brent D. , Schwend Harold S. , Vito Stephen T. 
Published: June 2011

SUMMARY
In this study we tested the hypothesis that a viscous thread releases its hold on a surface because its glycoprotein glue pulls from the surface and not because its elongating droplets break near their attachment to the surface. We compared the values obtained when three species' viscous threads adhered to four smooth surfaces, which differed in their total surface energy and in the proportions of their dispersion and polar energy components. Although water comprised 43–70% of the volume of these viscous droplets, only the dispersion surface energies of test materials and not their polar surface energies impacted thread adhesion. These results support the droplet pull-off hypothesis and are consistent with a previous finding that capillary force contributes little to thread adhesion. Just as a viscous thread's stickiness is constrained by the tensile strength of its supporting axial fibers, our findings suggest that glycoprotein adhesion is constrained by glycoprotein tensile strength.
Total mass balances of SO2-ethanol-water (SEW) fractionation of forest biomass
Authors: Yamamoto Minna , Iakovlev Mikhail , van Heiningen Adriaan 
Published: June 2011

AbstractThe overall target of this project, called Bioforest, is to develop an economic process for the production of commodity chemicals from mixed forest biomass, consisting of logging residues of hardwoods (HW) and softwoods (SW) and also from recycled fibers. The aim is to dissolve the biomass lignin and to produce monosugars based on hemicelluloses and hydrolyzed cellulose in high yield. The hydrolyzate could subsequently be converted into chemicals by modified acetone-butanol-ethanol fermentation. Here, the total mass balances of SO2-ethanol-water fractionation of different types of biomass feedstocks, such as SW and HW biomass, and deinked pulp are presented. Chemical composition of the feedstocks, solid residues (pulps) and spent liquors of fractionation were analyzed to gain more understanding about the fractionation procedure. The analysis was focused on carbohydrates, lignin, ash, acetyl groups and sugar degradation products. It was also examined if all feedstocks could be treated simultaneously in one digester because a larger feedstock supply within an economic transport radius improves the viability of the process. The fractionation approach was successful and it can be concluded that the method presented is very versatile for future applications in lignocellulosic biorefineries.
Lignin oxidation mechanisms under oxygen delignification conditions. Part 3. Reaction pathways and modeling
Authors: Kuitunen Susanna , Kalliola Anna , Tarvo Ville , Tamminen Tarja , Rovio Stella , Liitiä Tiina , Ohra-aho Taina , Lehtimaa Tuula , Vuorinen Tapani , Alopaeus Ville 
Published: June 2011

AbstractA detailed kinetic model for the lignin oxidation chemistry is presented. It is based mainly on the mechanisms and kinetics presented in the literature. Parameters that could not be found in the literature were regressed against the experimental data obtained from oxidation experiments with softwood kraft lignin. In addition to the detailed model for the chemistry, acid-base equilibrium reactions and gas-liquid mass transfer were modeled. Most of the experimental observations could be reproduced with the developed model. The reasons behind the behavior of guaiacyl and condensed phenols are discussed. The reaction routes affecting lignin solubilization and chemical consumption are presented. Model-ing of acid-base equilibria proved to be important because acid-base pairs of reactants react differently. Carbon dioxide buffers the pH and in this way affects the chemical reactions through the pH. A similar model could also be developed for other lignin treatments; for example, waste water purification or chemicals production in new biorefinery concepts. The developed reaction scheme will be used as a part of oxygen delignification model.
Bioaccumulation of U(VI) by Sulfolobus acidocaldarius under moderate acidic conditions
Authors: Reitz T. , Merroun M. L. , Rossberg A. , Steudtner Robin , Selenska-Pobell Sonja 
Published: June 2011

Abstract
U(VI) accumulation by the acidothermophilic archaeon Sulfolobus acidocaldarius at a moderate acidic pH of 4.5 was investigated. This pH value is relevant for some heavy metal and uranium polluted environments where populations of S. acidocaldarius were found to persist. We demonstrate that U(VI) is rapidly complexed by the archaeal cells. A combination of X-ray absorption spectroscopy and time-resolved laser-induced fluorescence spectroscopy revealed that at pH 4.5 organic phosphate and carboxylic groups are involved in the U(VI) complexation. These results are in contrast to those published for most bacteria which at this pH precipitate U(VI) mainly in inorganic uranyl phosphate phases. As demonstrated by TEM only a limited part of the added U(VI) was biomineralized extracellularly in the case of the studied archaeon. Most of the U(VI) accumulates were localized in a form of intracellular deposits which were associated with the inner side of the cytoplasma membrane. Observed differences in U(VI) bioaccumulation between the studied archaeon and bacteria can be explained by the significant differences in their cell wall structures as well as by their different physiological characteristics.
Ternary uranium(VI) carbonato humate complex studied by cryo-TRLFS
Authors: Steudtner Robin , Sachs S. , Schmeide K. , Brendler V. , Bernhard Gert 
Published: June 2011

AbstractThe complex formation of U(VI) with humic acid (HA) in the presence of carbonate was studied by time-resolved laser-induced fluorescence spectroscopy at low temperature (cryo-TRLFS) at pH 8.5. In the presence of HA, a decrease of the luminescence intensity of U(VI) and no shift of the emission band maxima in comparison to the luminescence spectrum of the UO2(CO3)34−complex, the dominating U(VI) species under the applied experimental conditions in the absence of HA, was observed. The formation of a ternary U(VI) carbonato humate complex of the type UO2(CO3)2HA(II)4−starting from UO2(CO3)34−was concluded from the luminescence data. For this complex a complex stability constant of logK=2.83 ± 0.17 was determined. Slope analysis resulted in a slope of 1.12 ± 0.11, which verifies the postulated complexation reaction. The results agree very well with literature data. Speciation calculations show that the formation of the ternary U(VI) carbonato humate complex can significantly influence the U(VI) speciation under environmental conditions.
Aluminous porcelain degradation study using mechanoacoustic and microscopic methods
Authors: Ranachowski Przemysław , Rejmund Feliks , Ranachowski Zbigniew , Pawełek Andrzej , Piątkowski Andrzej 
Published: June 2011

Aluminous porcelain degradation study using mechanoacoustic and microscopic methods
This experimental paper comprises the results of acoustic emission (AE), microscopic and ultrasonic measurements of samples subjected to slowly increasing compressive stress. On the basis of conducted measurements the successive stages of the material structural degradation have been recognized. The objects of study were samples made of C 120 aluminous porcelain. The investigated material has found at present the application in the fabrication of technical elements like overhead power line insulators. In the case of such objects, not only high mechanical strength, but especially elevated durability as well as operational reliability are required. The expected "life time" of net insulators during exploitation is about 40 years. The analysis of obtained mechanoacoustic dependences pointed out a complex mechanism of degradation of the material. Microscopic investigation of samples, which were stressed to different levels of load, enabled to specify the development of gradual growth of microcracks and successive crushing out of elements of the structure. These processes appear to be similar to the ageing processes occurring in the material during long period of exploitation under a working load. Three stages of the structure degradation were distinguished. The preliminary and subcritical ones show low or moderate intensity of AE signals and considerable variety for the particular samples. The critical stage directly precedes the destructtion of samples. Its range is relatively narrow and reveals the AE activity of high energy. The effectiveness of dispersive and fibrous reinforcement of modern aluminous porcelain C 120 type has been described. Structural strengthening by corundum grains and mullite needle shaped crystals improves mechanical parameters and distinguishes this material from typical aluminosilicate ceramics. The presented results enable drawing up the conclusions concerning the resistance of investigated material to the ageing degradation process development during long term operation.
Investigation of the skull melting method for the generation of particulate material of inorganic compounds
Authors: Riemer Björn , Lange Enno , Hameyer Kay 
Published: June 2011

Investigation of the skull melting method for the generation of particulate material of inorganic compoundsThis paper describes the application of the skull melting method for an artificial generation of particulate material of inorganic compounds like CsOH, NaOH, SnO2and UO2. The skull melting process is analyzed analytically. Thereby the electromagnetic field is calculated by a one dimensional time harmonic model. Thermal losses are estimated by simple analytical formulas. Finally an electromagnetic thermal field coupling is performed to calculate the temperature distribution inside the crucible, considering transient thermal effects. The skull melting process is simulated for the example of UO2. Under consideration of the given material properties it is shown that the skull melting method can be applied to fuse UO2.
The effect of the conditions of a landscape on its retention capacity
Authors: Vrána K. , Dostál T. , Koudelka P. , David V. , Uuléřová K. 
Published: June 2011

The effect of the conditions of a landscape on its retention capacityQuestions related to the occurrence, frequency, intensity, duration, characteristics and causes of floods have been discussed more in recent years. Two basic approaches to flood control often conflict. The first is based on the assumption of the considerable effect of a landscape's retention capacity, which can in fact prevent surface runoff generation and flood formation and can significantly transform flood wave. The second approach asserts that the retention capacity of a landscape is nearly negligible and that the only reliable flood protection can be provided by extending the technical structures of flood control measures mainly and directly on water courses. Two different approaches were applied to assess the effect of landscape conditions and revitalization measures on surface runoff and flood formation within a catchment and floodplain. The conclusion shows that the effect of landscape revitalization is very important, but mainly for low return periods of flood events, while for extreme events, the effect on landscapes and floodplains becomes less important and even negligible.
Adaptive Exercises Generation Using an Automated Evaluation and a Domain Ontology: The ODALA+ Approach
Authors: Farida Bouarab Dahmani , Malik Si Mohammed , Catherine Comparot , Pierre Jean Charrel 
Published: June 2011

Generating adapted learning contents is one of the most important activity that can give the best progression of a learner. This is why research on personalization of learning is growing to get learning environments able to adapt the learning activities and contents to the learnerâ??s profile. This last contains information about knowledge, skills, behavior, of the learner, at a given time of the learning process and for given domains. This information, to be effective, must be collected directly from an evaluation module that the learning system will systematically integrate in particular with the learning by doing mode.
After the satisfactory results of our research on teaching domain modeling and automated evaluation of learnerâ??s in the case of learning by doing exercises, we propose in this paper the ODALA+ approach which is an extension of the already proposed approach called ODALA (Ontology Driven Auto-evaluation Learning Approach) by adding two steps for learnerâ??s profile calculation using the evaluation results and for generating adapted exercises.