2,434 research outputs found
Multipurpose High Frequency Electron Spin Resonance Spectrometer for Condensed Matter Research
We describe a quasi-optical multifrequency ESR spectrometer operating in the
75-225 GHz range and optimized at 210 GHz for general use in condensed matter
physics, chemistry and biology. The quasi-optical bridge detects the change of
mm wave polarization at the ESR. A controllable reference arm maintains a mm
wave bias at the detector. The attained sensitivity of 2x10^10 spin/G/(Hz)1/2,
measured on a dilute Mn:MgO sample in a non-resonant probe head at 222.4 GHz
and 300 K, is comparable to commercial high sensitive X band spectrometers. The
spectrometer has a Fabry-Perot resonator based probe head to measure aqueous
solutions, and a probe head to measure magnetic field angular dependence of
single crystals. The spectrometer is robust and easy to use and may be operated
by undergraduate students. Its performance is demonstrated by examples from
various fields of condensed matter physics.Comment: submitted to Journal of Magnetic Resonanc
Validation and Use of 22Na Turnover to Measure Food Intake in Free-Ranging Lizards
As the food intake of free-ranging animals has proved to be difficult to measure by traditional means, the feasibility of using radioactive Na to measure food consumption in a small scincid lizard (Lampropholis guichenoti) was assessed. This technique has previously been used only for several species of mammal. A significant relationship between food intake and Na turnover was found in the laboratory, with Na turnover underestimating intake by 7.6%. The food intake of free-ranging members of a field population was estimated by 22Na turnover to be 9.55, 0.65, 9.39 and 13.75 mg dry weight (day)-1 during autumn, winter, spring and summer respectively. Estimates of assimilated and expended energy from these food intake values agree closely with data reported for other lizards using alternative techniques. This study also describes the technical innovations which were necessary to study lizards weighing less than 1 g; and it suggests that 22Na can provide an easy, reliable and inexpensive means of studying the energetics of many free-living animals
Emergent global patterns of ecosystem structure and function from a mechanistic general ecosystem model
Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures
First two unrelated cases of isolated sedoheptulokinase deficiency: A benign disorder?
We present the first two reported unrelated patients with an isolated sedoheptulokinase (SHPK) deficiency. The first patient presented with neonatal cholestasis, hypoglycemia, and anemia, while the second patient presented with congenital arthrogryposis multiplex, multiple contractures, and dysmorphisms. Both patients had elevated excretion of erythritol and sedoheptulose, and each had a homozygous nonsense mutation in SHPK. SHPK is an enzyme that phosphorylates sedoheptulose to sedoheptulose-7-phosphate, which is an important intermediate of the pentose phosphate pathway. It is questionable whether SHPK deficiency is a causal factor for the clinical phenotypes of our patients. This study illustrates the necessity of extensive functional and clinical workup for interpreting a novel variant, including nonsense variants
A survey of assistive technologies and applications for blind users on mobile platforms: a review and foundation for research
This paper summarizes recent developments in audio and tactile
feedback based assistive technologies targeting the blind
community. Current technology allows applications to be
efficiently distributed and run on mobile and handheld
devices, even in cases where computational requirements are
significant. As a result, electronic travel aids, navigational
assistance modules, text-to-speech applications, as well as
virtual audio displays which combine audio with haptic
channels are becoming integrated into standard mobile devices.
This trend, combined with the appearance of increasingly user-
friendly interfaces and modes of interaction has opened a
variety of new perspectives for the rehabilitation and
training of users with visual impairments. The goal of this
paper is to provide an overview of these developments based on
recent advances in basic research and application development.
Using this overview as a foundation, an agenda is outlined for
future research in mobile interaction design with respect to
users with special needs, as well as ultimately in relation to
sensor-bridging applications in genera
Morphological characterization of the blood cells in the endangered Sicilian endemic pond turtle,Emys trinacris(Testudines: Emydidae)
In this study, measurements of morphological parameters, sizes and frequencies of peripheral blood cells (erythrocytes,
leukocytes, thrombocytes) on blood smear preparation devices stained with May-Grünwald stain were evaluated for both
sexes in 20 Emys trinacris (Testudines: Emydidae) specimens. Erythrocytes were higher in male than in female specimens.
The leukocyte of E. trinacris contains eosinophil, basophil, monocyte, heterophil and lymphocyte. The eosinophil was higher
in males than in females whereas lymphocytes were higher in females than in males. The erythrocyte morphological
parameters (EL [erythrocyte length], EW [erythrocyte width], L/W [length/width], ES [erythrocyte size]) were compared
with the same data from Emys orbicularis s.l, and from species belonging to other chelonian genera. The erythrocyte size did
not vary within the studied Palearctic Emys taxa, whereas it proved to differ from that observed in other chelonians
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
Cooperation of local motions in the Hsp90 molecular chaperone ATPase mechanism
The Hsp90 chaperone is a central node of protein homeostasis activating a large number of diverse client proteins. Hsp90 functions as a molecular clamp that closes and opens in response to the binding and hydrolysis of ATP. Crystallographic studies define distinct conformational states of the mechanistic core implying structural changes that have not yet been observed in solution. Here, we engineered one-nanometer fluorescence probes based on photo-induced electron transfer into yeast Hsp90 to observe these motions. We found that the ATPase activity of the chaperone was reflected in the kinetics of specific structural rearrangements at remote positions that acted cooperatively. Nanosecond single-molecule fluorescence fluctuation analysis uncovered that critical structural elements that undergo rearrangement are mobile on a sub-millisecond time scale. We identified a two-step mechanism for lid closure over the nucleotide-binding pocket. The activating co-chaperone Aha1 mobilizes the lid of apo Hsp90, suggesting an early role in the catalytic cycle
Effect of different concentrations of olive oil and oleic acid on the mechanical properties of albumen (egg white) edible films
The main objective of this study was to investigate the effect of olive oil and oleic acid addition to albumin (egg white) through emulsification to produce films on mechanical properties. Plasticizer was necessary to maintain film and coating integrity and to avoid pores cracks. Edible composite films were prepared from albumin and lipid material at (1 and 1.5%), respectively. The effect of unsaturated oleic acid with glycerol and monounsaturated olive oil on tensile strength, elongation at break, water vapor permeability (WVP), opacity (OP), solubility, colour and atomic force microscopy (AFM) was investigated. In general, the incorporation of lipid materials resulted in the increase (P < 0.05) of tensile strength and elongation at break, and the reduction of WVP with some exceptions. Overall, the effect of monounsaturated was greater than that of unsaturated. The surface microstructure of the films was analyzed using atomic force microscopy (AFM).Key words: Albumin protein, edible film, olive oil, oleic acid, mechanical properties
Adaptively evolved Escherichia coli for improved ability of formate utilization as a carbon source in sugar???free conditions
Background: Formate converted from CO2 reduction has great potential as a sustainable feedstock for biological production of biofuels and biochemicals. Nevertheless, utilization of formate for growth and chemical production by microbial species is limited due to its toxicity or the lack of a metabolic pathway. Here, we constructed a formate assimilation pathway in Escherichia coli and applied adaptive laboratory evolution to improve formate utilization as a carbon source in sugar-free conditions.
Results: The genes related to the tetrahydrofolate and serine cycles from Methylobacterium extorquens AM1 were overexpressed for formate assimilation, which was proved by the 13C-labeling experiments. The amino acids detected by GC/MS showed significant carbon labeling due to biomass production from formate. Then, 150 serial subcultures were performed to screen for evolved strains with improved ability to utilize formate. The genomes of evolved mutants were sequenced and the mutations were associated with formate dehydrogenation, folate metabolism, and biofilm formation. Last, 90 mg/L of ethanol production from formate was achieved using fed-batch cultivation without addition of sugars.
Conclusion: This work demonstrates the effectiveness of the introduction of a formate assimilation pathway, combined with adaptive laboratory evolution, to achieve the utilization of formate as a carbon source. This study suggests that the constructed E. coli could serve as a strain to exploit formate and captured CO2
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