gebhart/patrepeval huggingface dataset:
When Perfusion Meets Diffusion: <i>in vivo</i> Measurement of Water Permeability in Human Brain (2006)

Quantification of water permeability can improve the accuracy of perfusion measurements obtained with arterial spin labeling (ASL) methods, and may provide clinically relevant information regarding the functional status of the microvasculature. The amount of labeled water in the vascular and tissue compartments in an ASL experiment can be estimated based on their distinct diffusion characteristics, and in turn, water permeability determined from the relative vascular and tissue contributions. In the present study, a hybrid magnetic resonance imaging technique was introduced by marrying a continuous ASL method with a twice-refocused spin-echo diffusion sequence. Series of diffusion-weighted ASL signals were acquired with systematically varied b values. The signals were modeled with fast and slow decaying components that were associated with the vascular and tissue compartments, respectively. The relative amount of labeled water in the tissue compartment increased from 61% to 74% and to 86% when the postlabeling delay time was increased from 0.8 to 1.2 and to 1.5 secs. With a b value of 50 secs/mm2, the capillary contribution (fast component) of the ASL signal could be effectively minimized. Using the single-pass approximation model, the water permeability of gray matter in the human brain was estimated based on the derived relative water fractions in the tissue and microvasculature. The potential for in vivo magnetic resonance mapping of water permeability was showed using two diffusion weighted ASL measurements with b=0 and 50 secs/mm2 in both healthy subjects and a case of brain tumor.
Compliant Joint Actuator With Dual Spiral Springs (2013)

The main motivation behind the creation of a compliant actuation system is to provide safety, capability of storing energy, and improved performance levels in dynamic tasks. The choice of the proper compliance level pertaining to robots depends on the specific purposes of the robots. In this paper, a dual-spiral-spring actuation system (DSSAS) is proposed to provide high compliance and deformation values for wearable robots. Among many different applications of wearable robotic systems, we aim for systems in which safety and compliance are more important than the control bandwidth of the joints. A spiral spring is selected to take advantage of the characteristics of high levels of compliance and deformation compared to other elastic components. The proposed dual-spiral-spring actuation system uses two spiral springs in opposite directions, as the spiral spring generates torque only in one direction. First, we present the characteristics of the spiral spring for a compliant joint. Then, the design and performance of the DSSAS are demonstrated by experiments.
Molecular Basis for Atovaquone Resistance in Pneumocystis jirovecii Modeled in the Cytochrome bc1Complex of Saccharomyces cerevisiae (2004)

Atovaquone is a substituted hydroxynaphthoquinone that is widely used to prevent and clear Plasmodium falciparum malaria and Pneumocystis jirovecii pneumonia. Atovaquone inhibits respiration in target organisms by specifically binding to the ubiquinol oxidation site at center P of the cytochrome bc(1) complex. The failure of atovaquone treatment and mortality of patients with malaria and P. jirovecii pneumonia has been linked to the appearance of mutations in the cytochrome b gene. To better understand the molecular basis of atovaquone resistance, we have introduced seven of the mutations from atovaquone-resistant P. jirovecii into the cytochrome b gene of Saccharomyces cerevisiae and thus obtained cytochrome bc(1) complexes resistant to inhibition by atovaquone. In these enzymes, the IC(50) for atovaquone increases from 25 nm for the enzyme from wild-type yeast to >500 nm for some of the mutated enzymes. Modeling of the changes in cytochrome b structure and atovaquone binding with the mutated bc(1) complexes provides the first quantitative explanation for the molecular basis of atovaquone resistance.
Production of N <sub>2</sub> through Anaerobic Ammonium Oxidation Coupled to Nitrate Reduction in Marine Sediments (2002)

In the global nitrogen cycle, bacterial denitrification is recognized as the only quantitatively important process that converts fixed nitrogen to atmospheric nitrogen gas, N(2), thereby influencing many aspects of ecosystem function and global biogeochemistry. However, we have found that a process novel to the marine nitrogen cycle, anaerobic oxidation of ammonium coupled to nitrate reduction, contributes substantially to N(2) production in marine sediments. Incubations with (15)N-labeled nitrate or ammonium demonstrated that during this process, N(2) is formed through one-to-one pairing of nitrogen from nitrate and ammonium, which clearly separates the process from denitrification. Nitrite, which accumulated transiently, was likely the oxidant for ammonium, and the process is thus similar to the anammox process known from wastewater bioreactors. Anaerobic ammonium oxidation accounted for 24 and 67% of the total N(2) production at two typical continental shelf sites, whereas it was detectable but insignificant relative to denitrification in a eutrophic coastal bay. However, rates of anaerobic ammonium oxidation were higher in the coastal sediment than at the deepest site and the variability in the relative contribution to N(2) production between sites was related to large differences in rates of denitrification. Thus, the relative importance of anaerobic ammonium oxidation and denitrification in N(2) production appears to be regulated by the availability of their reduced substrates. By shunting nitrogen directly from ammonium to N(2), anaerobic ammonium oxidation promotes the removal of fixed nitrogen in the oceans. The process can explain ammonium deficiencies in anoxic waters and sediments, and it may contribute significantly to oceanic nitrogen budgets.
Total synthesis of (+)-nojirimycin and (+)-1-deoxynojirimycin (1987)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTotal synthesis of (+)-nojirimycin and (+)-1-deoxynojirimycinHideo Iida, Naoki Yamazaki, and Chihiro KibayashiCite this: J. Org. Chem. 1987, 52, 15, 3337–3342Publication Date (Print):July 1, 1987Publication History Published online1 May 2002Published inissue 1 July 1987https://pubs.acs.org/doi/10.1021/jo00391a031https://doi.org/10.1021/jo00391a031research-articleACS PublicationsRequest reuse permissionsArticle Views2303Altmetric-Citations128LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Recent advances in crystalline and amorphous particulate protein formulations for controlled delivery (2016)

The number of particulate delivery systems for biologics is negligible compared to liquid dosage forms, signifying the complications associated with development of solid protein delivery systems. Particulate protein delivery systems can improve stability, reduce viscosity of suspensions at high protein concentration and allow for controlled drug release. This review discusses current advances in controlled delivery of particulate protein formulations. While the focus lies on protein crystals and delivery systems employing protein crystals, amorphous protein particles will also be addressed. Crystallization and precipitations methods and modifications allowing controlled delivery with and without encapsulation are summarized and discussed.
A Procedure for Culture of Cells From Mouse Tail Biopsies: <italic>Brief Communication</italic><xref ref-type="fn" rid="FN1">2</xref> (1978)

The synthesis and characterization of perylenediimide polyisocyanides is reported. In addn. to short oligomers, our synthetic approach results in the formation of extremely long, well-defined, and rigid perylenediimide polymers. Ordering and close-packing of the chromophores in these long polymers is guaranteed by attachment to a polyisocyanide backbone with amino acid side chains. Hydrogen bonding interactions between those groups stabilize and rigidify the helical polymer structure. The rodlike nature of the synthesized long perylenediimide pendant polyisocyanides as well as the helical arrangement of the chromophores is demonstrated by means of at. force microscopy. Remarkably, polymer fibers up to 1 mm in length have been visualized, contg. several thousands of perylenediimide mols. CD spectroscopy reveals the chiral organization of the chromophore units in the polymer, whereas absorption and emission measurements prove the occurrence of excited-state interactions between those moieties due to the close packing of the chromophore groups. However, an intricate optical behavior is encountered in bulk as a result of the coexistence of short oligomers and long polymers of perylenediimide, a situation subsequently uncovered by means of single-mol. expts. Individual long helical perylenediimide polyisocyanides exhibit a typical red-shifted fluorescence spectrum, which, together with depolarized emission continuously decreasing in time, demonstrate that fluorescence arises from multiple excimer-like species in the polymer. Upon continuous irradn. of these long polymers, a fast decay in fluorescence lifetime is obsd., a situation explained by photoinduced creation of quenching sites. Radical/ion formation by intramol. electron transfer between close-by perylenediimide moieties is the most probable mechanism for this process. Appropriate control of the electron-transfer process might open the possibility of applying these polymers as perylenediimide-based supramol. nanowires. [on SciFinder (R)]
Revised Prevalence Estimates of Mental Disorders in the United States (2002)

Establishing the clinical significance of disorders in the community is crucial for estimating treatment need. More work should be done in defining and operationalizing clinical significance, and characterizing the utility of clinically significant symptoms in determining treatment need even when some criteria of the disorder are not met. Discrepancies in ECA and NCS results are largely due to methodologic differences.
Spammer success through customization and randomization of URLs (2015)

Spam researchers and security personnel require a method for determining whether the URLs embedded in email messages are safe or potentially hostile. Prior research has been focused on spam collections that are quite insignificant compared to real-world spam volumes. In this paper, researchers evaluate 464 million URLs representing nearly 1 million unique domains observed in email messages in a six day period from November 2014. Four methods of customization and randomization of URLs believed to be used by spammers to attempt to increase deliverability of their URLs are explored: domain diversity, hostname wild-carding, path uniqueness, and attribute uniqueness. Implications of the findings suggest improvements for “URL blacklist” methods, methods of sampling to decrease the number of URLs that must be reviewed for safety, as well as presenting some challenges to the ICANN, Registrar, and Email Safety communities.
Construction and Characterization of <i>Moraxella catarrhalis</i> Mutants Defective in Expression of Transferrin Receptors (1999)

We have previously reported the construction of an isogenic mutant defective in expression of OmpB1, the TbpB homologue, in Moraxella catarrhalis 7169. In this report, we have extended these studies by constructing and characterizing two new isogenic mutants in this clinical isolate. One mutant is defective in expression of TbpA, and the other mutant is defective in expression of both TbpA and TbpB. These isogenic mutants were confirmed by using PCR analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sequencing. In vitro growth studies, comparing all three mutants, demonstrated that the tbpA mutant and the tbpAB mutant were severely limited in their ability to grow with human holotransferrin as the sole source of iron. In contrast, the ompB1 (tbpB) mutant was capable of utilizing iron from human transferrin, although not to the extent of the parental strain. While affinity chromatography with human holotransferrin showed that each Tbp was capable of binding independently to transferrin, solid-phase transferrin binding studies using whole cells demonstrated that the tbpA mutant exhibited binding characteristics similar to those seen with the wild-type bacteria. However, the ompB1 (tbpB) mutant exhibited a diminished capacity for binding transferrin, and no binding was detected with the double mutant. These data suggest that the M. catarrhalis TbpA is necessary for the acquisition of iron from transferrin. In contrast, TbpB is not essential but may serve as a facilitory protein that functions to optimize this process. Together these mutants are essential to provide a more thorough understanding of iron acquisition mechanisms utilized by M. catarrhalis.
Maternalism (2016)

Maternalism refers to the concept that women possess particular characteristics that make them uniquely suitable to care for children as well as to a movement going by the same name that sought to enhance state care for women and children while also increasing women's participation in the paid workforce. Maternalism is therefore primarily concerned with women's ability to mother. However, the movement contained contradictions that impacted upon its ability to push for reforms for the welfare of women and children.
Hierarchical Multimodal Mesoporous Carbon Materials with Parallel Macrochannels (2007)

Hierarchically structured multimodal meso-macroporous carbon materials have been prepared by using the nanoreplication of the mesoporous walls of a meso-macroporous zirconia exotemplate. Like the zirconia exotemplate, the pure carbon material possesses funnel shaped straight macrochannels, parallel to each other and perpendicular to the tangent of the particles' dense mesoporous shell. As a result of the funnel-like shape, each macrochannel has a pore size gradient with a large opening centered at 300−700 nm. The walls of the macrochannels and the dense mesoporous shells are formed by a hierarchical mesostructured porous system with uniform mesopore sizes centered at 3, 15−17, and 25−50 nm. Macrochannels are interconnected with hierarchically mesostructured walls and shells. A high surface area of 950 m2/g with a mesopore volume of 0.44 cm3/g is obtained. The possibility of the nanoreplication of other meso-macroporous oxides such as aluminosilicates, titania, and niobium oxide with different macrochannel size, shape, and organization has also been studied to generate meso-macroporous carbon materials with different organizations of the macrochannels.
An Automatic LO Leakage Calibration Method for Class-AB Power Mixer Based RF Transmitters (2018)

Mixers in a transmitter typically use pseudo differential common-source baseband amplifiers driving local oscillator (LO) switches. The common-source amplifiers are biased near cut-off for class-AB operation which yields higher efficiency. To mitigate their non-linearity, they are usually preceded by feedback controlled pre-distortion circuitry. DC bias differences between the two pseudo-differential halves of the common-source amplifiers turns out to be a major source of LO leakage. This paper presents an automatic calibration method to reduce the LO leakage. Major contributors of LO leakage in class-AB based power mixers with enhanced linearity and baseband noise filtering is analyzed. Monte Carlo analysis shows that LO leakage is less than -35dBc for 17% of the cases without calibration and 98% of the cases with calibration.
Multilayer aperture-coupled broadside microstrip lines (2002)

This paper describes new multilayer aperture-coupled broadside microstrip lines suitable for miniaturized microwave monolithic integrated circuits (MMICs). The new transmission line structure is applicable to both loose and tight coupling applications. The quasi-static spectral domain method is used to determine both the c- and /spl pi/-mode characteristic impedances and effective dielectric constants.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Maxima for Graphs and a New Proof of a Theorem of Turán (1965)

Maximum of a square-free quadratic form on a simplex. The following question was suggested by a problem of J. E. MacDonald Jr. (1): Given a graph G with vertices 1, 2, . . . , n. Let S be the simplex in E n given by x i ≥ 0, Σ x i = 1. What is
Spatio-temporal ultrawideband indoor propagation modelling by reduced complexity geometric optics (2007)

A simple and efficient virtual-source ray-tracing technique for the simulation of indoor wideband radio and optical propagation channels is proposed. The parametric deterministic model considers the room geometry, transceiver locations, material properties and probe signal types. It is applied to the indoor ultrawideband channel in the FCC-allocated 3.1–10.6 GHz band, and a range of novel results are presented to illustrate several possible applications. The channel small-scale fading statistics and spatial variability are examined by synthesising a densely sampled aperture. Multiple-antenna array systems are simulated to evaluate multiple-input multiple-output performance. The multipath angular characteristics are analysed from the simulated azimuth-delay profile. The simulation results closely match previous channel measurement studies and statistical models, validating the proposed technique. It is shown that specular reflection is dominant, and power convergence is achieved with three reflections in a typical indoor environment. Thus, it is demonstrated that despite its simplicity, the model yields reliable and accurate results, and can therefore be a useful tool for indoor wireless network planning and performance prediction.
The protective action of glycols against freezing damage of mouse and rat embryos (1978)

Eight-cell mouse and rat embryos were frozen to -79 degrees C or -196 degrees C in the presence of ethylene, diethylene, triethylene, propylene or polyethylene glycol. Ethylene glycol was the most effective cryoprotectant for mouse and rat embryos and considerable protection against damage during freezing and thawing was also afforded by propylene glycol. The degree of protection given by the other glycols was relatively low. Mouse embryos survived freezing after only 0.1 min exposure to ethylene glycol at 0 degrees C but exposure for longer periods was necessary with the other glycols. Mouse embryos that survived freezing and thawing with a glycol as the protective agent were capable of developing to full-term fetuses.
Integrated On-Chip Nano-Optomechanical Systems (2017)

Recent developments in integrated on-chip nano-optomechanical systems are reviewed. Silicon-based nano-optomechanical devices are fabricated by a two-step process, where the first step is a foundry-enabled photonic circuits patterning and the second step involves in-house mechanical device release. We show theoretically that the enhanced responsivity of near-field optical transduction of mechanical displacement in on-chip nano-optomechanical systems originates from the finesse of the optical cavity to which the mechanical device couples. An enhancement in responsivity of more than two orders of magnitude has been observed when compared side-by-side with free-space interferometry readout. We further demonstrate two approaches to facilitate large-scale device integration, namely, wavelength-division multiplexing and frequency-division multiplexing. They are capable of significantly simplifying the design complexity for addressing individual nano-optomechanical devices embedded in a large array.
Suppression of mode switching noise in wavelength stabilized laser diodes by external Bragg gratings (2013)

Special applications require low noise wavelength stabilized diode lasers for pumping of solid state lasers. We report on intensity noise in the frequency range of kHz to MHz due to bi-stable mode switching between external cavity modes in laser diodes with volume Bragg grating as external reflector. Two regimes of bi-stability are identified which are attributed to switching between longitudinal or lateral resonator modes. The origin of noise is explained by thermal bi-stability which can be suppressed by proper design of the external resonator. Low noise operation of single mode ridge waveguide lasers is demonstrated having the potential of scaling up the pump power by using ridge waveguide arrays.
Brain Morphology in Children With Specific Language Impairment (1997)

The planum temporale and pars triangularis have been found to be larger in the left hemisphere than the right in individuals with normal language skills. Brain morphology studies of individuals with developmental language disorders report reversed asymmetry or symmetry of the planum, although the bulk of this research has been completed on adults with dyslexia. Pars triangularis has not been studied in the developmental language impaired population. In this study, magnetic resonance imaging (MRI) was used for quantitative comparisons of the planum temporale (Wernicke's area) and pars triangularis (Broca's area) in children with specific language impairment (SLI) and children with normal language skills. The subjects were 11 children with SLI and 19 age- and sex-matched controls between 5.6 and 13.0 years old. Each subject received a neurolinguistic battery of tests and a high resolution volumetric MRI scan. Major results were that (a) pars triangularis was significantly smaller in the left hemisphere of children with SLI, and (b) children with SLI were more likely to have rightward asymmetry of language structures. Furthermore, anomalous morphology in these language areas correlated with depressed language ability. These findings support the hypothesis that language impairment is a consequence of an underlying neurobiological defect in areas of the brain known to subserve language.
Argonne National Laboratory superconducting pulsed coil program (1979)

The main objectives are to develop high current (approx. 100 kA) cryostable cable configurations with reasonably low ac losses, to build a demonstration pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat. A 1.5-MJ cryostable pulsed superconducting coil has been developed and constructed at ANL. The coil has a peak field of 4.5 T at an operating current of 11.0 kA. A large inexpensive plastic cryostat has been developed for testing the pulsed coil. The coil has been pulsed with a maximum dB/dt of 11 T/s. The coil was pulsed more than 4000 cycles. Detailed results of the ac loss measurements and the current sharing of the cryostability will be described. (MOW)