julilili42/papers huggingface dataset:
Relation between the X-ray and optical luminosities in binary systems with accreting nonmagnetic white dwarfs
2014-04-01

We investigate the relation between the optical (g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brightness does not drop below Mg~13-14. Using the latter fact, we show that in current and planned X-ray sky surveys, the family of accreting nonmagnetic white dwarfs can be completely identified to the distance determined by the sensitivity of an optical sky survey in this region. For the Sloan Digital Sky Survey (SDSS) with a limiting sensitivity m_g~22.5, this distance is ~400-600 pc
Fluorescence Imaging of Human Cells with a Novel Conjugate of the Antifungal Nystatin
2014-04-01

The antitumor activity of antibacterial and antifungal compounds has been of interest in the past. In several investigations glycopeptide antibiotics like bleomycin and antifungal agents like itraconazole have shown direct positive results whereas antifungal polyenes such as amphotericin B have been shown to potentiate the effects of antitumor agents. After having investigated the fluorescence-marked antibacterial glycopeptides vancomycin and ramoplanin on various malignant and healthy human cells in previous studies, the present work is focused on the antifungal polyene nystatin. We coupled nystatin to the fluorescent dye fluorescein isothiocyanate (FITC). After confirming the correct mass by mass spectrometry the effect of the conjugate on nine different human cell lines (two benign and seven tumor cell lines) was examined. The character of the uptake was determined by confocal laser scanning microscopy (CLSM) and the uptake was quantified by fluorescence activated cell sorting (FACS). The addition of propidium iodide (PI) allowed for detection and quantification of cell membrane disruption caused by the fluorescein-nystatin conjugate. Uptake of the conjugate was found to vary among the nine cell lines investigated. Conjugate uptake was strongest after 6 hours in most cell lines. Only the two prostate carcinoma cell lines PC3 and LNCaP showed further increase in uptake after long-time (24h) incubation. PI staining in general correlated well with the conjugate FITC staining values. The Colo205 colon carcinoma cell line and the U373 and LN18 glioblastoma cell lines exhibited very low conjugate uptake and PI staining. The results indicate that this conjugate shows potential for future imaging studies on certain human cancer cells.
Unusual presentation of cerebral venous sinus thrombosis associated with contraceptive usage.
2014-04-01

A 23-year-old woman was referred to our department complaining of intermittent double vision for 3 weeks. Best corrected visual acuity (BCVA) was 20/20 in both eyes (OU), the pupils were round and reactive to light with no relative afferent pupillary defect (RAPD), intraocular pressure (IOP) was 12mmHg OU; color vision by Ishihara pseudo-isochromatic plates and automated visual fields (Figure 1) were normal OU, as well. Orthoptic examination showed slight limitation of abduction and partial sixth nerve palsy in the left eye (OS). Dilated fundoscopy revealed bilateral optic disc edema (Figure 2). A high dose steroid (methylprednisolone) was initially administered with the clinical suspicion of an underlying neuro-inflammatory process. Figure 1 Visual field testing (Octopus): no significant defects were detected in the right (upper image) and left (lower image) eyes. Figure 2 Dilated fundoscopy: bilateral optic disc edema at presentation. Magnetic resonance imaging (MRI) excluded intracranial masses, hemorrhage, meningitis or other similar conditions causing optic disc edema. Lumbar puncture revealed elevated cerebrospinal fluid (CSF) opening pressure at 46 mmHg (normal up to 16 mmHg) with no abnormal constituents, therefore papilledema was verified. There was no history of weight gain, obesity, migraine headaches or tobacco use. The patient had been using an oral birth control pill, Yasmin 28 (drospirenone and ethinyl estradiol) over the past 5 months. No abnormal findings were detected on an extensive hematology panel including erythrocyte sedimentation rate (ESR), complete blood count (CBC), kidney function, C-reactive protein (CRP) and partial thomboplastin time (PTT). Magnetic resonance venography (MRV) showed partial venous thrombosis of the right transverse and sigmoid sinuses (Figure 3). Figure 3 Magnetic resonance venography demonstrates partial venous thrombosis of the right transverse and sigmoid sinuses (arrows). Fraxiforte® (nadroparin calcium) injections 0.4 ml once daily, Sintrom® (acenocoumarol) and acetazolamide 250mg twice daily were administered as initial treatment and the steroid was tapered. One week later, BCVA and color vision were stable at 20/20 OU and 13/13 OU, respectively. Six months later the fundoscopic appearance improved, Sintrom® was discontinued and acetazolamide was reduced to 250mg daily for 1 month and 125mg daily for the next month. Ten months after the episode, the patient was clinically stable and optic disc edema had completely regressed (Figure 4). Figure 4 Dilated fundoscopy: resolution of optic disc edema in both eyes, ten months later.
Frequency reconfigurable box shaped narrow band monopole antenna
2014-04-01

A novel design of small frequency reconfigurable monopole antenna has been proposed. The antenna was entirely made of copper and reconfigurability was achieved by changing positions of ground connections. Three antenna configurations that resonate at 2.2, 2.7 and 3.4GHz were presented. The prototype measurements show good agreement with the simulation results.
In vitro elastogenesis (87.1)
2014-04-01

Background: Elastic fibers are one of the main components of the extracellular matrix (ECM), providing dynamic tissues such as lungs, skin, blood vessels, heart valve leaflets and ligaments with flexibility and elasticity. However, the complex process of elastic fiber assembly is poorly understood und the generation of elastic fibers on a human base is a missing link in tissue engineering. Methods: A constant shear stress providing, fluid flow bioreactor system was designed and evaluated. For in vitro studies, human vascular smooth muscle cells (VSMCs) were seeded onto three‐dimensional (3D) electropsun scaffolds and cultured in the bioreactor system. After 6 days dynamic culture, the scaffolds were harvested and analyzed regarding elastin gene and protein expression. The produced ECM was investigated applying immunostaining of elastogenesis‐associated proteins and transmission electron microscopy (TEM). Results: After a 6 day dynamic culture of VSMCs on 3D scaffolds, a significant increase of elastin gene and protein expression was detected when comparing to the 2D cultures and static controls. Moreover, TEM confirmed a proper developed ECM similar to native fetal tissue, including long bundels of microfibrils, collagen and elastin. This is the first report showing developing elastic fibers as well as the availability of elastogenesis‐associated proteins on a human‐based tissue engineered construct.
Connexin 37 and KCa3.1 contribute to P2Y 2 receptor initiated endothelial‐derived hyperpolarization (1079.15)
2014-04-01

Nucleotides such as ATP and UTP are important paracrine regulators of vascular tone. Importantly, we previously demonstrated that in vivo activation of P2Y 2 receptors (activated by ATP/UTP) causes an acute NO‐independent decrease in blood pressure (BP), indicating this signaling pathway requires an endothelial‐derived hyperpolarization (EDH) response. To define the mechanisms by which in vivo activation of P2Y 2 receptors initiates EDH and vasodilation, we studied connexin 37 and 40 (Cx37, Cx40), both part of the myoendothelial gap junction, as well as big‐conductance (KCa1.1, expressed in smooth muscle cells) and intermediate‐conductance K channels (KCa3.1, expressed in endothelial cells), all hypothesized to be part of the EDH response. We compared the effects of the P2Y 2/4 receptor agonist, INS45973, in wild‐type (WT) mice and mice lacking Cx37, Cx40, KCa1.1, or KCa3.1 (n=4‐5/genotype) under anesthesia, while monitoring intra‐arterial BP. Acute application of INS45973 (0.01, 0.03, 0.1, 0.3, 1, or 3 mg/kg bw i.v. in 0.5 μl/g bw over 45 sec) dose‐dependently and rapidly (within 15 sec of starting infusion) decreased BP in WT mice (max response % of baseline: ‐38±1%, EC50: 0.8±0.2 mg/kg) for 2‐3 min. Whereas the responses in Cx40‐/‐ and KCa1.1‐/‐ mice were comparable to WT mice (‐41±2%, 0.3±0.1 mg/kg and ‐44±3%, 0.3±0.1 mg/kg, respectively), responses in Cx37‐/‐ and KCa3.1‐/‐ mice were significantly impaired (‐27±1%, 1.2±0.3 mg/kg and ‐13±5%, 1.6±0.8 mg/kg, respectively). Heart rate was not affected in either genotype. Our data indicate that Cx37 and KCa3.1 are required, at least in part, for the P2Y 2 receptor‐initiated EDH response and subsequent vasodilation. Grant Funding Source : 10SDG2610034 and P30DK079337
Reconstructing the acoustic scenes encountered by free-flying, foraging bats
2014-04-01

Aerial insectivorous bats face the challenge of efficient echo scene analysis for localizing obstacles and capturing prey in flight. Data collected with a telemetry microphone mounted on the foraging bat's head provide a valuable opportunity to reconstruct acoustic scenes comprised of echoes returning to the bat's ears. This study explores the information embedded in echoes from a tethered insect and background clutter recorded by the telemetry microphone in laboratory experiments. Using images from high-speed video cameras and recordings from a far-field microphone array, angular information about different objects in the echoes are restored by assimilating the reconstructed bat's position and echolocation beam aim with respect to the objects along its flight trajectory toward prey capture. This procedure is further augmented by theoretical simulations using acoustic scattering principles to circumvent the limitation imposed by the sensitivity and signal-to-noise ratio of the telemetry microphone. The reconstructed acoustic scenes offer an avenue for detailed analysis of important cues for figure-ground separation in a cluttered environment, and serve as a basis for subsequent neurocomputational modeling of auditory scene analysis performed by the bat's sonar receiver.
Sleep for cognitive enhancement
2014-04-02

Sleep is essential for effective cognitive functioning. Loosing even a few hours of sleep can have detrimental effects on a wide variety of cognitive processes such as attention, language, reasoning, decision making, learning and memory. While sleep is necessary to ensure normal healthy cognitive functioning, it can also enhance performance beyond the boundaries of the normal condition. This article discusses the enhancing potential of sleep, mainly focusing on the domain of learning and memory. Sleep is known to facilitate the consolidation of memories learned before sleep as well as the acquisition of new memories to be learned after sleep. According to a widely held model this beneficial effect of sleep relies on the neuronal reactivation of memories during sleep that is associated with sleep-specific brain oscillations (slow oscillations, spindles, ripples) as well as a characteristic neurotransmitter milieu. Recent research indicates that memory processing during sleep can be boosted by (i) cueing memory reactivation during sleep; (ii) stimulating sleep-specific brain oscillations; and (iii) targeting specific neurotransmitter systems pharmacologically. Olfactory and auditory cues can be used, for example, to increase reactivation of associated memories during post-learning sleep. Intensifying neocortical slow oscillations (the hallmark of slow wave sleep (SWS)) by electrical or auditory stimulation and modulating specific neurotransmitters such as noradrenaline and glutamate likewise facilitates memory processing during sleep. With this evidence in mind, this article concludes by discussing different methodological caveats and ethical issues that should be considered when thinking about using sleep for cognitive enhancement in everyday applications.
Leukodystrophies underlying cryptic spastic paraparesis: frequency and phenotype in 76 patients
2014-04-02

Background and purpose In chronic progressive spasticity of the legs many rare causes have to be considered, including leukodystrophies due to neurometabolic disorders. To determine the frequency of leukodystrophies and the phenotypic spectrum patients with cryptic spasticity of the legs were screened for underlying neurometabolic abnormalities. Methods Seventy‐six index patients presenting with adult‐onset lower limb spasticity of unknown cause consistent with autosomal recessive inheritance were included in this study. Screening included serum levels of very long chain fatty acids for X ‐linked adrenoleukodystrophy/adrenomyeloneuropathy and lysosomal enzyme activities in leukocytes for metachromatic leukodystrophy, GM 1‐gangliosidosis, T ay− S achs, S andhoff and K rabbe disease. If clinical evidence was indicative of other types of leukodystrophies, additional genetic testing was conducted. Clinical characterization included neurological and psychiatric features and magnetic resonance imaging. Results Basic screening detected one index patient with metachromatic leukodystrophy, two patients with K rabbe disease and four patients with adrenoleukodystrophy/adrenomyeloneuropathy. Additional genetic testing revealed one patient with vanishing white matter disease. These patients accounted for an overall share of 11% of leukodystrophies. One patient with K rabbe disease and three patients with adrenoleukodystrophy/adrenomyeloneuropathy presented with pure spasticity of the lower limbs, whilst one patient each with K rabbe disease, metachromatic leukodystrophy and adrenoleukodystrophy/adrenomyeloneuropathy showed additional complicating symptoms. Conclusions Adult patients presenting with cryptic spasticity of the legs should be screened for underlying X ‐linked adrenoleukodystrophy/adrenomyeloneuropathy and lysosomal disorders, irrespective of the presence of additional complicating symptoms. Leukodystrophies may manifest as late as the sixth decade and hyperintensity of cerebral white matter on magnetic resonance FLAIR images is not obligatory.
Parametric Amplification of the Mechanical Vibrations of a Suspended Nanowire by Magnetic Coupling to a Bose-Einstein Condensate
2014-04-02

We show how the vibrational modes of a nanowire may be coherently manipulated with a Bose-Einstein condensate of ultracold atoms. We consider the magnetomechanical coupling between paramagnetic atoms and a suspended nanowire carrying a dc current. Atomic spin flips produce a backaction onto the wire vibrations, which can lead to mechanical mode amplification. In contrast to systems considered before, the condensate has a finite energy bandwidth in the range of the chemical potential and we explore the consequences of this on the parametric drive. Applying the resolvent method, we determine the threshold coupling and we also find a significant frequency shift of the vibration due to magnetomechanical dressing.
Principles of Vibrational Spectroscopic Methods and their Application to Bioanalysis
2014-04-02

Vibrational spectroscopy, particularly FTIR, has been in use for a long time to determine secondary structure features of biomolecules. FTIR studies of proteins and peptides are usually concerned with the amide groups and their deuterium-substituted analogs and carboxyl groups. FTIR spectroscopy is ideal for the study of conformational changes and protein unfolding, as well as investigation of hydration effects around and inside biomolecules. It is also much used in the study of biomembranes and biomembrane-associated proteins, providing possibilities to study surface orientation. FTIR has been successfully applied to the study of adsorption of biomolecules to solid surfaces, involving either attenuated total reflection (ATR) or grazing incidence reflection (GIR) accessories. FTIR microscopy has provided possibilities for the study of proteins in their native environment, such as in serum, whole blood, bone, brain tissue, and many other matrices. Although the application of FTIR directly to clinical studies and diagnosis has been very much debated, some promising results have been obtained for the in vivo monitoring of glucose, hemoglobin, urea, albumin, phosphocreatine, and nitric oxide. A significant portion of this chapter focuses on various types of Raman spectroscopy, including SERS, as well as terahertz (THz) spectroscopy. In particular, it will present the state of the art in Raman, including laser sources, spectrometers, detectors, Raman microscopy (confocal and micro-Raman), Raman imaging, fiber optic probes for in vivo and in vitro analysis, and methods to obtain depth profile information. The issue of fluorescence interference will be considered from the perspectives of excitation wavelength selection and data treatment. Methods to optimize signal to noise with minimized excitation laser irradiance to avoid sample damage are also discussed. This chapter then reviews applications of Raman spectroscopy to bioanalysis. Areas discussed include pathology, cytopathology, single-cell analysis, in vivo and in vitro tissue characterization, chemical composition of cell components, proteomics, metabolomics, large-scale screening, microorganism identification, biocompatible materials, and counter biowarfare methods. Finally, surface-enhanced Raman spectroscopy (SERS) is still much used for determination of the functional groups that are in direct contact with noble metal surfaces or nanostructures. Finally, terahertz spectroscopy has given many new possibilities for studies of low-frequency interactions between electromagnetic radiation and biomaterials. In contrast to spectroscopic techniques at shorter wavelengths, THz spectroscopy directly probes long-range dynamics in biomolecules (such as conformation of DNA and proteins), vibrations of inter- and intramolecular hydrogen bonds in solid-state materials, as well as picosecond dynamics in liquid solutions. This chapter reviews modern instrumentation and techniques for THz spectroscopy, with emphasis on applications in bioanalysis.
Photoelectron Spectroscopy Applications to Materials Science
2014-04-02

The detailed understanding of complex materials requires the use of state-of-the-art experimental techniques that provide information on the electronic properties of the materials. Therefore, the aim of this book chapter is to give an overview on a powerful technique as photoemission spectroscopy is. Photoemission experiments deliver a wealth of information on a large number of different aspects connected with the characterization of a system, ranging from core levels states to chemical environment, from interface effects and bonding to growth. We focus on the basic concepts that represent the background of the photoemission experiments. In addition, we review some investigations showing that this technique not only gives information on the occupied states, but its use sheds light on several aspects as bonding of adsorbates with substrates, growth modes, and structural properties in thin films.
NEXAFS Studies at Surfaces
2014-04-02

The detailed understanding of complex materials requires the use of state-of-the-art experimental techniques that provide information on electronic and magnetic properties of the materials. Therefore, the aim of this chapter is to give an overview on a faceted technique as edge X-ray absorption fine structure spectroscopy (NEXAFS). We focus on the basic concepts that represent the background of the photon absorption in the X-ray range by electrons distributed within specific orbitals in a population of molecules or atoms. In addition, we review some NEXAFS investigations showing that this technique only gives information on the unoccupied states, but its use sheds light on several aspects as oxidation states, bonding of adsorbates with substrates, molecular orientation, and structural properties in thin films.
Direct Optical Detection in Bioanalytics
2014-04-02

In addition to the measurement of fluorescence in bioanalytics and color change read-out in ELISA plates, more and more direct optical detection principles are used, especially in miniaturized arrays. This chapter provides an introduction to the optical principles of micro-reflectometry and micro-refractometry, discusses the pros and cons of the different methods, and describes the requirements in physics and application to bioassays. For various assay types (direct, competitive, binding inhibition, and sandwich), the advantages of direct optical detection for various applications such as antibody/antigen, enzyme inhibition, DNA hybridization, protein/protein interaction, and so on, are discussed. The possibilities of obtaining kinetic and thermodynamic data, including free standard reaction enthalpies and entropies, are given. These ideas are demonstrated by means of a few examples.
Scanning Near‐Field Gap‐Mode Microscopy
2014-04-02

Since the pioneering days of scanning near-field optical microscopy, an important goal has always been to combine the scanning probe microscopy techniques with spectroscopic means for characterizing the chemical structure of materials with nanometer spatial resolution. This turned out to be a demanding but fascinating endeavor, as the nanoscale optical and spectroscopic phenomena manifest distinctive characteristics different from those observed at the macroscopic scale. This challenge continues to stimulate worldwide researchers from physics, chemistry, and engineering streams to investigate light–matter interactions at dimensions much smaller than the wavelength of electromagnetic radiation (d ≪ λ). Widespread applications of such investigations are demonstrated, for example, in material sciences (maximizing photovoltaic energy conversion), in engineer sciences (pursuing quantum devices at the quantum limit with single photons), or in life sciences (as local optical sensors to observe chemical processes in living cells). With the development of nanophotonics and nanotechnology, the understanding of light–matter interaction in the subwavelength regime has been considerably deepened and more and more new microscopic spectroscopy techniques have been invented. In this chapter, we will introduce an effective high-resolution scanning near-field optical microscopy method – scanning near-field gap-mode microscopy (SNGM), which combines optical spectroscopy and scanning probe microscopy. In the following sections, we lead you through the principles, the theoretical background, the experimental realization, and the applications of this technique. Our goal is to develop an intuitive picture of this fascinating ultramicroscopic technique and to discuss the physical processes that allow us to extract optical information from a sample with nanometer spatial resolution and sensitivity down to the single-molecule level.
Raman Spectroscopy Fundamentals
2014-04-02

This chapter contains sections titled: Theory Qualitative Analysis Experimental Details Raman Data Treatment and Calibration Raman Spectral Databases Database Searching Extensible Markup Language (XML) Data Model References