bluuebunny/crossref_metadata_2025 huggingface dataset:
Education as Aesthetic Experience
Authors: Weddington Hank S.
Published: April 2004

This article examines the characteristics marking human beings engaged in aesthetic experience as envisioned by John Dewey. Of interest is the interaction between self and other distinguished by emotional self-investment, intellectual hospitality, vulnerability to loss, and existential responsibility. Such interaction opens spaces where human beings experience and provide opportunities for transformation. In this sense, aesthetic experience is a continual source of reciprocal transformations and thus a ceaseless unfolding of growth. If one conceptualizes education as aesthetic experience, it becomes manifest in human interaction as opposed to passive reception. Education becomes an existential constant instead of a solitary school-based activity. A classroom narrative is offered as exemplifying such an educational conception and then analyzed for the marking characteristics of aesthetic experience. Readers arrive at a conception of education that counters current educational policies alienating human beings from one another and thus from interactions that may provide and sustain growth.
Influence of Substrate Bias Pretreatment on Growth of Diamond Films by HFCVD
Authors: Kromka A. , Balon F. , Daniš T. , Pavlov J. , Janík J. , Dubravcová V. , Červeň I.
Published: April 2004

In the hot filament CVD (HFCVD) process, the nucleation process is enhanced by ion bombardment of the negatively biased substrate. To achieve ion bombardment at voltages as low as possible, a hybrid HFCVD technique was developed utilising a dual plasma arrangement. The I- V measurements of the plasma formed between the substrate and the filaments showed that the saturation of the total current depends on the process duration and substrate bias. A low nucleation bias voltage, i.e. ≤ 100 V, results in poor nucleation and non-continuous film formation. An increase in substrate bias voltage up to 120 V results in homogeneous nucleation and subsequent deposition of diamond films consisting mainly of large rectangle-like crystals. Further increase in nucleation voltage to ≥ 140 V leads to the formation of films with increased density of grains, which show edges with streak and cracking features indicating a twinning growth. During nucleation, the total current on the substrate has a tendency to increase with time, except for the sample nucleated at 100 V. The time constant, defined as the point when the total current starts to increase, is reduced with increase in substrate bias. It is proposed that this effect is related to the increased density of diamond nucleation sites.
Getting a Better Breast Image
Authors: Hubbard Anne
Published: April 2004

This article shows some of the pits I have fallen into over the last 15 years, with hints on trying to stay out of them.
Prevention of hepatopulmonary syndrome and hyperdynamic state by pentoxifylline in cirrhotic rats
Authors: Sztrymf B. , Rabiller A. , Nunes H. , Savale L. , Lebrec D. , Le Pape A. , de Montpreville V. , Mazmanian M. , Humbert M. , Hervé P.
Published: April 2004

Inhibition of tumour necrosis factor‐α (TNF‐α), levels of which are increased in the blood of cirrhotic rats, prevents hyperdynamic circulatory state, mainly by decreasing the vascular overproduction of nitric oxide. Hepatopulmonary syndrome, which is characterised by intrapulmonary vascular dilatation and increased alveolar to arterial oxygen tension difference (PA-a,O2), is mainly related to pulmonary overproduction of NO by macrophages accumulated in lung vessels. Since TNF‐α is a potent activator of macrophagic inducible nitric oxide synthase (NOS), the aim of this study was to investigate whether TNF‐α inhibition prevented hepatopulmonary syndrome and hyperdynamic circulatory state in rats with cirrhosis.

TNF‐α was inhibited by 5 weeks of pentoxifylline (10 mg·kg body weight−1·day−1) in rats with cirrhosis induced by common bile duct ligation.

Cardiac output, pulmonary and systemic vascular resistance,PA-a,O2and cerebral uptake of intravenous technetium‐99m‐labelled albumin macroaggregates (which reflects intrapulmonary vascular dilatation) were similar in sham- and pentoxifylline-treated cirrhotic rats. Blood TNF‐α concentrations and pulmonary intravascular macrophage sequestration, as assessed by morphometric analysis and radioactive colloid uptake, were decreased with pentoxifylline. Pentoxifylline also prevented increases in aorta and lung NOS activities and inducible NOS expression.

Thus pentoxifylline prevents development of hyperdynamic circulatory state and hepatopulmonary syndrome, probably by inhibiting the effects of tumour necrosis factor‐α on vascular nitric oxide synthase and intravascular macrophages. These results support an important role for tumour necrosis factor‐α in the genesis of hepatopulmonary syndrome.
Nontuberculous mycobacteria in non‐HIV patients: epidemiology, treatment and response
Authors: Henry M.T. , Inamdar L. , O'Riordain D. , Schweiger M. , Watson J.P.
Published: April 2004

Recent international guidelines published in 1997 and 1999 have proposed diagnostic and treatment criteria for disease caused by nontuberculous mycobacteria (NTM).

In this paper, the epidemiological data, diagnostic criteria, treatment regimens and outcomes from 117 HIV‐negative patients who had a positive culture for NTM between 1995–1999 are reviewed. The authors wished to identify factors associated with improved outcome in these patients.

A total of 71 patients were believed to have a clinical disease caused by NTM, as defined by international criteria. A total of 72% patients were found to have had pulmonary disease. There was a rise in infections between 1995–1999, with a peak in infections in 1997. The most striking rise was inMycobacterium aviumintracellulare complex infections (1995: 33% infections; 1996: 36% infections; 1997: 41% infections; 1998: 61% infections; 1999: 57% infections). There was a link between deprivation and number of positive NTM isolates (34.4% isolates occurred in the areas of lowest Carstairs deprivation indexversus20.6% isolates from areas of least deprivation). There was a significant association between appropriate therapy, defined by American Thoracic Society and British Thoracic Society guidelines, and successful outcome (74%) in contrast to those who received inappropriate treatment prior to the publication of these guidelines.

Nontuberculous mycobacteria infections remain a significant problem in non‐HIV patients. Adherence to published guidelines may improve patient outcomes.
Diesel particulate filter pressure drop Part 2: On-board calculation of soot loading
Authors: Haralampous O. A. , Kandylas I. P. , Koltsakis G. C. , Samaras Z. C.
Published: April 2004

In the first part of this study, an improved model for the calculation of pressure drop in particulate filters was presented with special emphasis on the soot permeability properties and its dependence on temperature and pressure. With the assumption of uniform wall flow distribution throughout the channel length, it was also possible to derive an analytical expression that was validated against experimental data on an engine bench. Using the results of pressure drop modelling, it is possible to carry out ‘inverse’ calculations of the soot mass in the filter based on the measurements of flowrate, temperature and backpressure, which forms the main subject of the present work. This approach is tested successfully against experimental data in filters of different geometry and material, yielding promising results. Such computations may be very helpful for the interpretation of experimental results in engine testing. In this paper, typical applications in the field of reaction rate assessment are presented. Moreover, model-based soot loading calculations are expected to assist the implementation of regeneration and on-board diagnostics strategies for particulate filters.
Follicular dendritic cell sarcoma arising from the hypopharynx
Authors: Georgalas Christos , Kanagalingam Jeeve , Gallimore Andrew , O’Flynn Paul
Published: April 2004

Follicular dendritic cell (FDC) tumours have been described recently as malignant tumours arising from accessory cells of the lymph nodes. They are rare tumours with fewer than 70 cases occurring worldwide. They usually present in cervical or abdominal lymph nodes,with very few occurring extranodally. We present the first case of an FDC tumour to occur in the hypopharynx with simultaneous cervical node metastases. The pathology is discussed and the literature reviewed.
Practice Abstracts
Authors: Keefer Donald L.
Published: April 2004

“Practice Abstracts” carries short reports of specific current or recent OR/MS projects. Often these reports are based on existing documents, such as internal reports or company newsletters. We hope that these abstracts will be accessible, interesting, and valuable to practitioners in other organizations. Contributions should be sent for evaluation to the editor of “Practice Abstracts,” Donald L. Keefer, Department of Supply Chain Management, Arizona State University, Box 874706, Tempe, Arizona 85287-4706 (don.keefer@asu.edu).
Nu-kote’s Spreadsheet Linear-Programming Models for Optimizing Transportation
Authors: LeBlanc Larry J. , Hill James A. , Greenwell Gregory W. , Czesnat Alexandre O.
Published: April 2004

Nu-kote International manufactures ink-jet, laser, and toner cartridges; ribbons; and thermal fax supplies. We developed spreadsheet linear-programming models for planning shipments of finished goods between vendors, manufacturing plants, warehouses, and customers to minimize overall cost subject to maximum-shipping-distance policies. Nu-kote used versions of these linear programs (LPs) to model supply chains with different warehouse configurations. The LPs have between 5,000 and 9,700 variables and 2,452 constraints. Nu-kote has used these LPs for an inherently nonlinear problem to identify improved shipments that will reduce annual costs by approximately $1 million and customer transit time by two days. It has already saved $425,000 from insight gained from the model.
Femtosecond Broadband Stimulated Raman: A New Approach for High-Performance Vibrational Spectroscopy
Authors: McCamant David W. , Kukura Philipp , Mathies Richard A.
Published: April 2004

Femtosecond stimulated Raman spectroscopy (FSRS) is a new technique that produces high-quality vibrational spectra free from background fluorescence. FSRS combines a narrow-bandwidth picosecond Raman pump pulse with an ∼80 fs continuum probe pulse to produce stimulated Raman spectra from the pump-induced gain in the probe spectrum. The high intensity of the Raman pump combined with the broad bandwidth of the probe produces high signal-to-noise vibrational spectra with very short data acquisition times. FSRS spectra of standard solutions and solvents such as aqueous Na2SO4, aqueous KNO3, methanol, isopropanol, and cyclohexane are collected in seconds. Furthermore, stimulated Raman spectra can be obtained using just a single pump–probe pulse pair that illuminates the sample for only ∼1 ps. Fluorescence rejection is demonstrated by collecting FSRS spectra of dyes (rhodamine 6G, chlorophyll a, and DTTCI) with varying degrees of fluorescence background and resonance enhancement. The high signal-to-noise, short data acquisition time, fluorescence rejection, and high spectral and temporal resolution of femtosecond stimulated Raman spectroscopy make it a valuable new vibrational spectroscopic technique.
Advances in the Raman Depth Profiling of Polymer Laminates
Authors: Froud C. A. , Hayward I. P. , Laven J.
Published: April 2004

The use of Raman microspectroscopy to depth profile multi-layered polymer laminates is becoming increasingly popular. However, the results are generally degraded by aberrations introduced by the change in refractive index at the air/sample interface. Recent research has suggested that the use of an immersion oil and suitable objective can reduce this effect. This study evaluates this proposal by comparing depth profiling results on a multi-layer poly(styrene)/poly(methylmethacrylate) (PS/PMMA) laminate polymer from both dry metallurgical objectives and immersion objectives (used in combination with an oil of suitable refractive index). The immersion technique enabled successful depth profiling to the full working distance of the objective (100 μm), showing clear and distinct variations in 11 different layers within the laminate; a dry metallurgical objective used for comparison achieved poor resolution of only two layers. This is the first demonstration of depth profiling within a polymer laminate to this depth. The depth profiling results are compared to results obtained by sectioning the PS/PMMA sample after setting it in resin.
On Confocal Raman Spectroscopy of Semicrystalline Polymers: The Effect of Optical Scattering
Authors: MacDonald A. M. , Vaughan A. S. , Wyeth P.
Published: April 2004

A series of semicrystalline polymers has been prepared through morphological control. Each of these has an identical refractive index but a different, well-defined, scattering behavior. From existing geometrical optical theories of confocal Raman spectroscopy, these materials should behave identically. Initially, the extent of scattering in each system was assessed quantitatively, from the near-infrared through the visible wavelength range, by UV/visible spectroscopy. The effect of optical scattering on the variation of intensity of the Raman scattered radiation with subsurface position was then examined in all four materials; the effect of surface roughness was also considered in the highest clarity system. Where surface effects are removed through careful sample preparation and the materials are interrogated using identical optical systems to mitigate against the impact of refractive index mismatch and other optical effects, the Raman response is strongly affected by the scattering characteristics of each material. A simple empirical relationship has been determined that adequately described all our specimens.
Infrared Reflection Spectroscopy of Thin Films on Highly Oriented Pyrolytic Graphite
Authors: Leitner Thomas , Kattner Jürgen , Hoffmann Helmuth
Published: April 2004

The properties of highly oriented pyrolytic graphite (HOPG) as a substrate for external reflection infrared spectroscopy in the mid-infrared region were investigated. Clean HOPG substrates, physisorbed hydrocarbon multilayers, and chemisorbed monolayers of p-substituted aryl radicals on HOPG were used as samples, and the experimental spectra were compared and complemented with the results of spectral simulations. From reflectivity measurements of clean HOPG surfaces with polarized light as a function of the light incidence angle and the frequency, the anisotropic optical constants n (refractive index) and k (absorption index) were determined for in-plane and out-of-plane directions with respect to the graphite basal plane. These constants express the semimetallic properties of HOPG, indicated by an intermediate reflectivity between a typical metal and a dielectric substrate and by asymmetric, distorted peak shapes in adsorbate film spectra, which represent a transition state between symmetrical, positive absorptions on metals and inverted, negative peaks on dielectric substrates. Regarding spectral sensitivity and surface selection rules, HOPG behaves much like a metal and is therefore an equally suitable substrate for external reflection infrared (IR) measurements.
Simultaneous Determination of the Pesticides Carbaryl and Thiabendazole in Environmental Samples by a Three-Dimensional Derivative Variable-Angle and a Synchronous Room-Temperature Phosphorescence Spectroscopy
Authors: Díaz B. Cañabate , Carretero A. Segura , Blanco C. Cruces , Gutiérrez A. Fernández
Published: April 2004

A three-dimensional derivative variable-angle synchronous scanning (DVASS) and a synchronous scanning (SS) heavy-atom room-temperature phosphorimetry (HAI-RTP) method are reported, for the first time, to identify and quantify the spectral overlapping phosphorescent pesticides thiabendazole (TBZ) and carbaryl (CBL). These pesticides are widely used in agriculture. The phosphorescence emission of the two compounds was obtained using sodium sulfite as the O2 scavenger and an external heavy atom salt. A careful selection of these experimental variables has been carried out. The increase of selectivity afforded by the DVASS and the SS methodology permitted the demonstration of its applicability to the simultaneous determination of phosphorescent signals of these two pesticides with overlapping spectral profiles. Limits of detection ranged between 1.4 ng/mL for TBZ and 1.7 ng/mL for CBL. The proposed method has been satisfactorily applied to the analysis of both pesticides in different types of water samples.
Simultaneous Monitoring of Organic Acids and Sugars in Fresh and Processed Apple Juice by Fourier Transform Infrared—Attenuated Total Reflection Spectroscopy
Authors: Irudayaraj Joseph , Tewari Jagdish
Published: April 2004

A combination of Fourier transform infrared spectroscopy (FT-IR) and chemometrics was used as a screening tool for the determination of sugars and organic acids such as sucrose, glucose, fructose, sorbitol, citric acid, and malic acid in processed commercial and extracted fresh apple juices. Prepared samples of synthetic apple juice in different constituent concentration ranges were scanned by attenuated total reflectance (ATR) accessory and the spectral region in the range between 950 and 1500 cm−1 was selected for calibration model development using partial least squares (PLS) regression and principal component regression (PCR). The calibration models were successfully validated by high-performance liquid chromatography (HPLC) measurements against several commercial juice varieties as well as juice extracted from different apple varieties to provide an overall R2 correlation of 0.998. The present study demonstrates that Fourier transform infrared spectroscopy could be used for rapid and nondestructive determination of multiple constituents in commercial and fresh apple juices. Results indicate this approach to be a rapid and cost-effective tool for routine monitoring of multiple constituents in a fruit juice production facility.
Rotational Invariants for Polarized Raman Spectroscopy
Authors: Frisk S. , Ikeda R. M. , Chase D. B. , Rabolt J. F.
Published: April 2004

A new method has been developed to determine an orientation-independent Raman scattered intensity based on various polarized Raman measurements. The equivalent term in infrared spectroscopy is the structural absorbance, which has existed for many years. As with the structural absorbance, the calculated Raman intensity allows one to observe spectral changes that are due uniquely to morphological changes in a set of different samples in the presence of orientation differences. The full theoretical development is presented, followed by an example based on a set of polymer fibers processed under different conditions leading to different morphologies and degrees of molecular orientation.
Semiautomated Depositor for Infrared Microspectrometry
Authors: Jarman Jessica L. , Seerley Shelly I. , Todebush Richard A. , De Haseth James A.
Published: April 2004

The measurement of minute samples is desirable in many areas of research and analysis, including biological, environmental, and forensic sciences. The use of manual solution direct deposition, combined with surface evaporation, is a very useful and convenient method for the transfer of many analytes to a spectroscopic sampling window. For Fourier transform infrared (FT-IR) spectrometric analysis, high quality attenuated total reflection (ATR) and transmission analyses are possible with suitable solution deposits. If the sample area is very small, placement of the analyte deposit on the active area of the sampling accessory must be done carefully. To achieve this, a novel direct deposition system has been developed. This system, a series of valves attached to a glass nebulizer, generates deposits that are reproducible, and placement of the deposits is precise. The valves allow the sample to be loaded, helium airflow to expel the sample, and the nebulizer to be cleaned after deposition. To help contain the sample to a small area once deposition has taken place, a vacuum line is attached to the nebulizer. This simple semiautomated deposition system allows for higher sensitivity and run-to-run reproducibility for minute sample analysis.
Analysis of Depth Profiling Data Obtained by Confocal Raman Microspectroscopy
Authors: Vyörykkä J. , Paaso J. , Tenhunen M. , Tenhunen J. , Iitti H. , Vuorinen T. , Stenius P.
Published: April 2004

The nominal depth resolution achieved in confocal Raman microscopy is on the order of a few micrometers. Often, however, the depth resolution is decreased by light refraction at the sample surface. The problem can be avoided with the use of an immersion objective and index matching oils. Through this intervention the instrument point-spread function (PSF) can be assumed to be independent of the depth of focus in the sample, and spatially invariant depth profiles can be acquired. In this work the instrument PSF was determined by measuring a depth profile of a thick uniform sample and calculating the first derivative of the depth profile curve. The first-derivative method was also used to determine sample thickness. Convolution with the PSF makes it possible to simulate the behavior of the instrument with different sample functions. It is also possible to use the instrument PSF to deconvolve depth-profiling data. Deconvolution reduces the blurring effect of the instrument and increases the depth resolution. Deconvolution can also be used in analysis of the sample surface position and in layer structure analysis. In this paper we show how the convolution integral can be used with the immersion sampling technique to determine the PSF and how the sample thickness can be determined.
Isotopic Measurements of Uranium Using Inductively Coupled Plasma Cavity Ringdown Spectroscopy
Authors: Wang Chuji , Mazzotti Fabio J. , Miller George P. , Winstead Christopher B.
Published: April 2004

Inductively coupled plasma cavity ringdown spectroscopy (ICP-CRDS) is applied to isotopic measurements of uranium. We have successfully obtained the isotopic-resolved spectra of uranium at three different atomic/ionic transition lines, 286.57, 358.49, and 409.01 nm. Of the three lines, the largest isotope shift of approximately 9 pm was measured at the 286.57 ionic line. Isotopic-resolved spectra were recorded in ratio of 1:1 (235U/238U, 2.5 μg/mL) and at the natural abundance ratio of 0.714% (235U/238U, 1.25 μg/mL 235U). The smallest measurable isotope shift of approximately 3 pm was determined for the 409.01 nm ion spectral line. Detection limits (DL) were obtained under optimized ICP operating conditions to be in the range of 70∼150 ng/mL, except for the 238U component of the 286.57 nm line (300 ng/mL). This latter result was determined to be due to a strong, previously unreported, absorption interference from the argon plasma. The 235U isotope component (DL 70 ng/mL) was found to be unaffected. This work demonstrates the applicability of ICP-CRDS for uranium isotopic measurements. The potential of development of a field-deployable, on-line uranium isotope monitor using plasma-CRDS is discussed.
Identification of Impurities in Phenylacetylene by Species-Selected Mass-Analyzed Threshold Ionization Spectroscopy
Authors: Lin Jung Lee , Tzeng Wen Bih
Published: April 2004

Two-color resonant two-photon mass-analyzed threshold ionization (MATI) spectroscopy was used to identify styrene impurities in a commercial phenylacetylene sample. With the mass-gating setup, the recorded MATI spectra are free of contamination from molecules of different mass. Analysis of these spectra gives information on the precise adiabatic ionization and the active cation vibrations, which can be used as fingerprints for the identification of molecular ions.
Reference Sample Method Reduces the Error Caused by Variable Cryosection Thickness in Fourier Transform Infrared Imaging
Authors: Rieppo Jarno , Hyttinen Mika M. , Jurvelin Jukka S. , Helminen Heikki J.
Published: April 2004

Fourier transform infrared imaging (FT-IRI) is a novel technique for characterization of the biochemical composition of biological tissues, e.g., articular cartilage. The use of cryosections is preferred in FT-IRI. Unfortunately, significant variation in section thickness often impairs the suitability of cryosections for quantitative FT-IRI analysis. The present study introduces an inexpensive reference sample method for quantitative analysis. In this technique, specimen absorption is normalized with that of nitrocellulose membrane embedded and cryosectioned with the sample. Mean variation of the infrared absorption in cartilage specimens was 11.5%, 12.1%, and 20.6% for 5 μm, 10 μm, and 14 μm thick sections, respectively, without normalization. Normalization reduced the variation to 5.2%, 4.0%, and 4.6% for the same sections, respectively. The normalization method enables usage of cryosections for quantitative work and significantly reduces the cost and time needed for FT-IRI analysis.
Digital Signal Processing for Step-Scan Phase and Electrochemical Potential Double-Modulation Fourier Transform Infrared Spectrometry
Authors: Brevnov Dmitri A. , Hutter Eliza , Fendler Janos H.
Published: April 2004

Step-scan double-modulation (phase and electrochemical potential) Fourier transform infrared (FT-IR) spectrometry provides both spectroscopic and dynamic information about faradaic reactions. Recently introduced digital signal processing (DSP) can be used, instead of two lock-in amplifiers, for the optical signal demodulation at two modulation frequencies. In order to establish the merits of double-modulation FT-IR spectrometry with DSP, spectro-electrochemical experiments are performed in the attenuated total reflection configuration and with the commonly used ferri/ferrocyanide redox couple. Because of a large potential drop associated with the uncompensated resistance, a satisfactory signal-to-noise ratio for the alternating current (ac) optical measurements is obtained only with the employment of positive feedback compensation. In this arrangement, the amplitude of electrochemical modulation is sufficiently large to convert a significant fraction of the reduced form to the oxidized form and back to the reduced form. Large amplitude ac voltammetry demonstrates that the phase of faradaic admittance at the formal potential is approximately 45° at 2.00 Hz. In addition, these experiments allow for calculation of the interfacial ac potential. This variable is needed for the normalization of the in-phase and the quadrature spectra in order to overcome the problem associated with the iRu drop. Because of the integral relationship between the faradaic current and the electromodulation reflectance coefficient, the phases of electromodulation reflectance coefficient with respect to the interfacial ac potential are expected to be −45° and 135° for the reduced and oxidized forms, respectively. However, dynamic information from double-modulation FT-IR spectrometry is available only if demodulation at the electrochemical potential modulation frequency is performed with respect to a defined phase. Because of an undefined demodulation phase implemented in the current version of DSP software, step-scan double-modulation FT-IR spectrometry with DSP is suitable only to provide spectroscopic information. In order to overcome this limitation, the demodulation of the ac optical signal at the electrochemical modulation frequency must be synchronized in phase with the ac potential modulation applied to the electrochemical cell.
On-Line Monitoring of the Density of Linear Low-Density Polyethylene in a Real Plant by Near-Infrared Spectroscopy and Chemometrics
Authors: Watari Masahiro , Higashiyama Hisamitsu , Mitsui Naoto , Tomo Masahiro , Ozaki Yukihiro
Published: April 2004

This paper reports on-line monitoring of the density of linear low-density polyethylene (LLDPE) by near-infrared (NIR) spectroscopy and chemometrics. The on-line monitoring was carried out not only in a laboratory but also in a real plant. We composed an on-line monitoring system for molten polymers consisting of a Fourier transform near-infrared (FT-NIR) spectrometer, input/output (I/O) module, a personal computer, and a sampling cell that we developed. We first compared NIR spectra of LLDPE in the solid and melt states and then developed calibration models that predict the density using partial least squares regression (PLS). The sample sets for developing prediction models were collected for three months at the plant, and the density of LLDPE was continuously monitored on-line for another three months using the model. The standard error of prediction (SEP) for the on-line monitoring of the density of LLDPE at the plant was ±2.1 mg/cm3 (range: 0.91–0.95 g/cm3).
Capabilities of Surface Composition Analysis Using a Long Laser-Induced Breakdown Spectroscopy Spark
Authors: Rodolfa Kit T. , Cremers David A.
Published: April 2004

An apparatus has been investigated based on laser-induced breakdown spectroscopy (LIBS) for the rapid determination of the spatial distribution of elements on surfaces. Cylindrical optics are used to create a linear spark approximately 1 cm in length. Light emitted by atoms excited along the spark is collected and provides a spatial profile of elemental composition in the sample when analyzed with a spectrometer and gated charge-coupled device (ICCD) detector. Moving the spark across the sample surface as spectral data is recorded at regularly spaced intervals allows for the development of a three-dimensional elemental distribution map (emission intensity versus spatial distribution across an area). An analysis of the spatial resolution of this methodology is presented along with representative data from several sample types. Application of full-image analysis allowing for simultaneous investigations into the spatial distributions of multiple elements is also discussed and results are presented.
Glucose Quantification in Dried-down Nanoliter Samples Using Mid-Infrared Attenuated Total Reflection Spectroscopy
Authors: Diessel Edgar , Willmann Stefan , Kamphaus Peter , Kurte Roland , Damm Uwe , Heise H. Michael
Published: April 2004

The aim of this study was to determine the feasibility of minimally invasive glucose concentration measurement of a body fluid within the physiologically important range below 100 nL with a number of samples such as interstitial fluid, plasma, or whole blood using mid-infrared spectroscopy, but starting with preliminary measurements on samples of simple aqueous glucose solutions. The Fourier transform infrared spectrometer was equipped with a Golden Gate® single reflection diamond attenuated total reflection (ATR) accessory and a room-temperature pyroelectric detector. As the necessary detection limits can be achieved only for dried samples within the spectrometric conditions realized by a commercial instrument, the work focused on the optimization of such ATR measurements. We achieved quantification of samples with volumes as low as 7 nL between 10 and 600 mg/dL. The standard error of prediction (SEP) for the concentration range 10–100 mg/dL is 3.2 mg/dL with full interval data between 1180 and 940 cm−1. The performance of the prediction is given by a coefficient of variation of prediction (CVpred) of 6.2%. When all samples within the whole concentration range are included, the SEP increases to 20.2 mg/dL, and hence the CVpred to 10.6% due to a nonlinear signal dependence on glucose concentration. A detection limit for glucose of 0.7 ng with a signal-to-noise ratio of 10 was obtained.
Optical Measurements of Ion Trajectories through the Vacuum Interface of an Inductively Coupled Plasma Mass Spectrometer
Authors: Macedone Jeffrey H. , Mills Andrew A. , Farnsworth Paul B.
Published: April 2004

A flexible laser excited fluorescence system has been used to trace ion trajectories in the first vacuum stage of an inductively coupled plasma mass spectrometer. The system has been used to record the spatial distributions of ions immediately upstream from the sampling cone and in the 10 mm downstream from the cone for a variety of positions of the plasma with respect to the sampling cone. The data were used in turn to test the efficacy of scanning the plasma across the sampling cone to generate maps of ion distributions in the plasma. The maps generated by scanning the plasma across the cone are close approximations of the ion distribution immediately upstream from the sampling cone, but are not representative of distributions in an unperturbed plasma.
Single Diode Laser Sensor for Wide-Range H2O Temperature Measurements
Authors: Gharavi Mohammadreza , Buckley Steven G.
Published: April 2004

A single diode laser absorption sensor (near 1477 nm) useful for simultaneous temperature and H2O concentration measurements is developed. The diode laser tunes approximately 1.2 cm−1 over three H2O absorption transitions in each measurement. The line strengths of the transitions are measured over a temperature range from 468 to 977 K, based on high-resolution absorption measurements in a heated static cell. The results indicate that the selected transitions are suitable for sensitive temperature measurements in atmospheric pressure combustion systems using absorption line ratios. Comparing the results with HITRAN 96 data, it appears that these transitions will be sensitive over a wide range of temperatures (450–2000 K), suggesting applicability for combustion measurements.
Reflectance Study of Compressed Paper
Authors: Oksman Antti , Silvennoinen Raimo , Peiponen Kai-Erik , Avikainen Marko , Komulainen Hannu
Published: April 2004

Reflectance of three paper grades was investigated using a pressure gauge, an imaging system, and a spectrophotometer. It was observed that under high pressure, dark-colored areas appear in paper when using the imaging system. The area of the dark pattern increases as the pressure is raised. Reflectance measurements as a function of wavelength confirmed that the dark patterns appear due to the contact of the paper and the probe window of the pressure gauge. Based on results by other researchers the amount and the nature of optical contact observed depends on structural properties of paper such as surface roughness, formation, and compressibility. Although there are differences in the spectral properties of different paper grades they all share the common feature that the reflectance is decreasing as a function of the applied pressure. An empiric result for the fine and the super-calendered (SC) paper samples measured is that they both have an exponential dependence of total reflectance as a function of applied pressure when the illumination wavelength is kept constant.
Voltage-Dependent Enhancement of Electrical Coupling by a Subthreshold Sodium Current
Authors: Curti Sebastián , Pereda Alberto E.
Published: April 2004

Voltage-dependent changes in electrical coupling are often attributed to a direct effect on the properties of gap junction channels. Identifiable auditory afferents terminate as mixed (electrical and chemical) synapses on the distal portion of the lateral dendrite of the goldfish Mauthner cells, a pair of large reticulospinal neurons involved in the organization of sensory-evoked escape responses. At these afferents, the amplitude of the coupling potential produced by the retrograde spread of signals from the postsynaptic Mauthner cell is dramatically enhanced by depolarization of the presynaptic terminal. We demonstrate here that this voltage-dependent enhancement of electrical coupling does not represent a property of the junctions themselves but the activation of a subthreshold sodium current present at presynaptic terminals that acts to amplify the synaptic response. We also provide evidence that this amplification operates under physiological conditions, enhancing synaptic communication from the Mauthner cells to the auditory afferents where electrical and geometrical properties of the coupled cells are unfavorable for retrograde transmission. Retrograde electrical communication at these afferents may play an important functional role by promoting cooperativity between afferents and enhancing transmitter release. Thus, the efficacy of an electrical synapse can be dynamically modulated in a voltage-dependent manner by properties of the nonjunctional membrane. Finally, asymmetric amplification of electrical coupling by intrinsic membrane properties, as at the synapses between auditory afferents and the Mauthner cell, may ensure efficient communication between neuronal processes of dissimilar size and shape, promoting neuronal synchronization.
Specific Na+Sensors Are Functionally Expressed in a Neuronal Population of the Median Preoptic Nucleus of the Rat
Authors: Grob Magali , Drolet Guy , Mouginot Didier
Published: April 2004

Whole-cell patch-clamp recordings were performed on acute brain slices of male rats to investigate the ability of the neurons of the median preoptic nucleus (MnPO) to detect fluctuation in extracellular osmolarity and sodium concentration ([Na+]out). Local application of hypotonic and hypertonic artificial CSF hyperpolarized and depolarized the neurons, respectively. Similar responses obtained under synaptic isolation (0.5 μM TTX) highlighted the intrinsic ability of the MnPO neurons to detect changes in extracellular osmolarity and [Na+]out. Manipulating extracellular osmolarity, [Na+]out, and [Cl-]outshowed in an independent manner that the MnPO neurons responded to a change in [Na+]outexclusively. The specific Na+response was voltage insensitive and depended on the driving force for Na+ions, indicating that a sustained background Na+permeability controlled the membrane potential of the MnPO neurons. This specific response was not reduced by Gd3+, amiloride, or benzamil, ruling out the participation of mechanosensitive cationic channels, specific epithelial Na+channels, and Phe-Met-Arg-Phe-gated Na+channels, respectively. Combination ofin situhybridization, using a riboprobe directed against the atypical Na+channel (NaX), and immunohistochemistry, using an antibody against neuron-specific nuclei protein, revealed that a substantial population of MnPO neurons expressed the NaXchannel, which was characterized recently as a concentration-sensitive Na+channel. This study shows that a neuronal population of the MnPO acts as functional Na+sensors and that the NaXchannel might represent the molecular basis for the extracellular sodium level sensing in these neurons.
Corticotropin-Releasing Factor and Urocortin I Modulate Excitatory Glutamatergic Synaptic Transmission
Authors: Liu Jie , Yu Baojian , Neugebauer Volker , Grigoriadis Dimitri E. , Rivier Jean , Vale Wylie W. , Shinnick-Gallagher Patricia , Gallagher Joel P.
Published: April 2004

Corticotropin-releasing factor (CRF)-related peptides serve as hormones and neuromodulators of the stress response and play a role in affective disorders. These peptides are known to alter complex behaviors and neuronal properties, but their receptor-mediated effects at CNS synapses are not well described. Here we show that excitatory glutamatergic transmission is modulated by two endogenous CRF-related peptide ligands, corticotropin-releasing factor [CRF rat/human (r/h)] and Urocortin I (Ucn I), within the central nucleus of the amygdala (CeA) and the lateral septum mediolateral nucleus (LSMLN). These limbic nuclei are reciprocally innervated, are involved in stress and affective disorders, and have high densities of the CRF receptors CRF1and CRF2. Activation of these receptors exerts diametrically opposed actions on glutamatergic transmission in these nuclei. In the CeA, CRF(r/h) depressed excitatory glutamatergic transmission through a CRF1-mediated postsynaptic action, whereas Ucn I facilitated synaptic responses through presynaptic and postsynaptic CRF2-mediated mechanisms. Conversely, in the LSMLN, CRF caused a CRF1-mediated facilitation of glutamatergic transmission via postsynaptic mechanisms, whereas Ucn I depressed EPSCs by postsynaptic and presynaptic CRF2-mediated actions. Furthermore, antagonists of these receptors also affected glutamatergic neurotransmission, indicating that endogenous ligands tonically modulated synoptic activity at these synapses.

These data show that CRF receptors in CeA and LSMLN synapses exert and maintain a significant synaptic tone and thereby regulate excitatory glutamatergic transmission. The results also suggest that CRF receptors may provide novel targets in affective disorders and stress.
Maintenance of Spatial and Motor Codes during Oculomotor Delayed Response Tasks
Authors: Curtis Clayton E. , Rao Vikas Y. , D'Esposito Mark
Published: April 2004

The most compelling neural evidence for working memory is persistent neuronal activity bridging past sensory cues and their contingent future motor acts. This observation, however, does not answer what is actually being remembered or coded for by this activity. To address this fundamental issue, we imaged the human brain during maintenance of spatial locations and varied whether the memory-guided saccade was selected before or after the delay. An oculomotor delayed matching-to-sample task (match) was used to measure maintained motor intention because the direction of the forthcoming saccade was known throughout the delay. We used a nonmatching-to-sample task (nonmatch) in which the saccade was unpredictable to measure maintained spatial attention. Oculomotor areas were more active during match delays, and posterior parietal cortex and inferior frontal cortex were more active during nonmatch delays. Additionally, the fidelity of the memory was predicted by the delay-period activity of the frontal eye fields; the magnitude of delay-period activity correlated with the accuracy of the memory-guided saccade. Experimentally controlling response selection allowed us to functionally separate nodes of a network of frontal and parietal areas that usually coactivate in studies of working memory. We propose that different nodes in this network maintain different representational codes, motor and spatial. Which code is being represented by sustained neural activity is biased by when in the transformation from perception to action the response can be selected.
Einfluss der Gehäusung auf den Entwurf und die Realisierung umweltrobuster, miniaturisierter Drucksensoren (Influence of Housing to Design and Manufacturing of Miniaturised Pressure Sensors for Harsh Environments)
Authors: Sindlinger Stefan , Wohlgemuth Christian , Werthschützky Roland
Published: April 2004

Zur Sicherung eines langfristigen Schutzes von piezoresistiven Silizium-Drucksensorelementen vor aggressiven Messmedien gibt es gegenwärtig keine Alternative zu Edelstahlgehäusen mit metallischen Trennmembranen und Koppelmedium. Der Einfluss der einzelnen Sensorbauteile auf das Übertragungsverhalten wird beim kompletten Entwurf des Differenzdrucksensors und der Auswahl der Fertigungstechnologien berücksichtigt. Auf Basis der so optimierten Entwurfsparameter wird die Konstruktion eines Differenzdrucksensors abgeleitet.
Lateral periodicity of elastic domains in MnAs/GaAs(001) epitaxial layers studied by high resolution X-ray diffraction
Authors: Jenichen Bernd , Kaganer Vladimir M. , Herrmann Claudia , Wan Li , Däweritz Lutz , Ploog Klaus H.
Published: April 2004

Periodic elastic domains in epitaxial films of MnAs(11̅00)/GaAs(001) are studied near the ferromagnetic phase transition. We obtain the period of the domain structure from the observed the X-ray diffraction satellites arising from the lateral periodicity. The application of the X-ray methods provides a high level of accuracy and gives information about average values over areas of several mm2. The observed periods are in a good agreement with those obtained by calculation and minimization of the elastic energy.
Paxlovid Is Effective but Underused—Here’s What the Latest Research Says About Rebound and More
Authors: Rubin Rita
Published: January 2024

This Medical News story examines the latest information about rebound, treatment eligibility, optimal dosing, and other questions related to nirmatrelvir-ritonavir for treating COVID-19.
What Is Your Secret to Health?
Authors: Levine Rebecca Ann
Published: January 2024

This essay describes how asking a single simple question helps the author understand the factors most important to patients and that could be indirectly considered the secret to their lives’ health, happiness, and longevity.
Outcomes in Clinical Subgroups of Patients With Alcohol-Related Hospitalizations
Authors: Friesen Erik L. , Mataruga Andrea , Nickel Nathan , Kurdyak Paul , Bolton James M.
Published: January 2024

Importance

Alcohol-related hospitalizations are common and associated with significant cost to the health care system. We have a limited understanding of the characteristics of individuals who experience alcohol-related hospitalizations, which limits our capacity to prioritize those at the highest risk of postdischarge harm.

Objective

To identify and characterize the clinical subgroups of individuals who are hospitalized for alcohol-related harms.

Design, Setting, and Participants

This cohort study used latent class analysis (LCA) to identify clinical subgroups of individuals experiencing alcohol-related hospitalizations in 2 provinces in Canada. All individuals between ages 10 and 105 years who were hospitalized for an alcohol-related harm between January 2017 and December 2018 (ie, the index hospitalization) were eligible. Data were analyzed between June 2023 and August 2023.

Exposures

The exposure of interest was the clinical subgroup that an individual belonged to. These subgroups were identified using an LCA based on (1) the characteristics of the index hospitalization and (2) the history of alcohol-related health service use.

Main Outcomes and Measures

In-hospital mortality, alcohol-related hospital readmission, and all-cause mortality in the year following discharge from the index hospitalization. The association between subgroup membership and the risk of in-hospital and postdischarge outcomes was evaluated using multivariable regression.

Results

A total of 34 043 individuals were included in analysis, 4753 from Manitoba (median [IQR] age, 49 [40-58] years; 1786 female [37.6%]) and 29 290 from Ontario (median [IQR] age, 57 [45-67] years; 8527 female [29.1%]). Seven subgroups were identified following a gradient from low-frequency service use for acute intoxication to high-frequency service use for severe alcohol use disorder and liver disease. In Ontario, there were 4431 individuals in the liver disease subgroup representing 15.5% of the cohort who were at the highest risk of 1-year mortality (1382 [31.2%]) relative to the acute intoxication subgroup (42 [4.0%]) (adjusted hazard ratio [aHR], 3.83; 95% CI, 2.80-5.24). There was also a small subgroup (10.6%) of individuals with high-frequency alcohol-related health service use who had a much higher hazard of readmission following the index hospitalization (1-year readmission: 703 of 1526 [46.1%] vs 104 of 1058 [9.8%] in the acute intoxication subgroup; aHR, 5.09; 95% CI, 4.11-6.31).

Conclusions and Relevance

In this population-based cohort study of individuals experiencing alcohol-related hospitalizations, we identified several small, clinically distinct subgroups that were at a disproportionately high risk of readmission and mortality. These groups could merit prioritization in strategies aimed at reducing the risk of adverse outcomes following alcohol-related hospitalizations.