2,261 research outputs found
Cantilever-based Resonant Microsensors with Integrated Temperature Modulation for Transient Chemical Analysis
This work introduces a resonant cantilever platform with integrated temperature modulation for real-time chemical sensing. Embedded heaters allow for rapid thermal cycling of individual sensors, thereby enabling real-time transient signal analysis without the need for a microfluidic setup to switch between analyte and reference gases. Compared to traditional mass-sensitive microsensors operating in steady state, the on-chip generation of signal transients provides additional information for analyte discrimination
Cantilever-based Resonant Gas Sensors with Integrated Recesses for Localized Sensing Layer Deposition
This work presents mass-sensitive hammerhead resonators with integrated recesses as a gas-phase chemical microsensor platform. Recesses are etched into the head region of the resonator to locally deposit chemically sensitive polymers by ink-jet printing. This permits the sensing films to be confined to areas that (a) are most effective in detecting mass loading and (b) are not strained during the in-plane vibrations of the resonator. As a result of the second point, even 5-μm thick polymer coatings on resonators with a 9-12 μm silicon thickness barely affect the Q-factor in air. This translates into higher frequency stability and ultimately higher sensor resolution compared to uniformly coated devices
Raman spectroscopy, a non-destructive solution to the study of glass and its alteration
This paper presents the potential of Raman spectroscopy, a non-destructive technique which can be applied in-situ, for the analyses of glass and their alteration. Recent analytical developments are summarised for different glass composition and practical examples are given. The paper describes how to extract compositional information from the glass, first based on the spectra profile to distinguish rapidly alkali silicate from alkaline-earth alkali silicate and lead alkali silicate glass, then using the spectral decomposition and correlations to extract quantitative data. For alkali silicate glasses, that are most prone to alteration, the spectral characteristics are described to interpret the alteration process (selective leaching or dissolution of the glass) from the Raman spectra of the altered glass. These developments have greatly widened the potential of the technique and supplement well its ability to measure the thickness of the altered layer and identify the crystalline deposits
Lp-cohomology of negatively curved manifolds
We compute the -cohomology spaces of some negatively curved manifolds.
We deal with two cases: manifolds with finite volume and sufficiently pinched
negative curvature, and conformally compact manifolds
Überinfusion von Verbrennungsopfern: häufig und schädlich
Zusammenfassung: Hintergrund: Schwerbrandverletzte (mehr als 20% verbrannter Körperoberfläche bei Erwachsenen) weisen in der ersten Phase (8-48h) einen durch das massive Kapillarleck bedingten Verbrennungsschock auf, der einer Infusionstherapie bedarf, um die Hämodynamik wieder herzustellen. Bis in die 80erJahre stellte eine unzureichende Flüssigkeitstherapie (Unterinfusion) die Haupttodesursache von Verbrennungspatienten dar. Seither ist die übermäßige Flüssigkeitstherapie (Überinfusion) zu einer beachtenswerten Quelle von Komplikationen geworden: abdominales Kompartmentsyndrom, Entlastungsschnitte (Escharotomie), Verschlechterung des Gasaustauschs, Verlängerung der künstlichen Beatmung und des Spitalaufenthalts. Die Überinfusion hat Ende der 90erJahre begonnen, wo innerhalb der ersten 24h Flüssigkeitsmengen zugeführt wurden, die weit über den 4ml/kg/%BSA ("burn surface area") der Parkland-Formel lagen. Ziel: Dieser Beitrag analysiert die Faktoren, welche zu einer Überinfusion führen können und zeigt Möglichkeiten, dem durch eine strikte Kontrolle der präklinischen Infusionstherapie sowie durch eine permissive Hypovolämie vorzubeuge
Using a value chain framework for food safety assessment of broiler and indigenous chicken meat systems of Nairobi
Purpose:
Research on livestock food systems in developing countries remains limited, yet this context needs to
be understood to investigate the epidemiology of zoonoses. The aim of this study was to use a value
chain framework to characterize the broiler and indigenous chicken meat systems of Nairobi and their
food safety risks.
Methods:
Using such a framework for food safety characterisation at system level is novel and has significant
potential in developing countries. Data collection involved 18 focus group discussions and 236
interviews with various poultry meat value chain stakeholders in Nairobi. Analysis included chain
mapping and identification of governance and food safety challenges.
Results:
The study identified 10 chain profiles, characterising the broiler and indigenous chicken systems, and
production-retailing continuum.
Food safety risks identified were related to lack of biosecurity, cold chain and access to water, poor
cleaning and hygiene practices, consumption of sick animals, significant environmental contamination
of by-products, and lack of inspection at farm slaughter.
Large companies dominated the governance of the broiler system through the control of day-old chick
production. Overall government control was relatively weak leading to minimal official regulatory
enforcement. Large companies and brokers were identified as dominant groups in market information
dissemination and price setting. No dominant group was identified for indigenous chicken profiles,
farming being at household level for local consumption, with quasi non-existent regulations. Lack of
industry association was system-wide, creating a barrier for access to capital. Other system barriers
included lack of space and expertise, leading to poor infrastructure and limited ability to implement
effective hygienic measures.
Conclusions and relevance:
Optimal food safety and disease control strategies should consider the structure of the poultry meat
system and stakeholder interactions to ensure effective programmes. This study provides a new
perspective for epidemiologists and public health officers to address food safety risks in full
understanding of the food system context
Propagation of gamma rays and production of free electrons in air
A new concept of remote detection of concealed radioactive materials has been
recently proposed \cite{Gr.Nusin.2010}-\cite{NusinSprangle}. It is based on the
breakdown in air at the focal point of a high-power beam of electromagnetic
waves produced by a THz gyrotron. To initiate the avalanche breakdown, seed
free electrons should be present in this focal region during the
electromagnetic pulse. This paper is devoted to the analysis of production of
free electrons by gamma rays leaking from radioactive materials. Within a
hundred meters from the radiation source, the fluctuating free electrons appear
with the rate that may exceed significantly the natural background ionization
rate. During the gyrotron pulse of about 10 microsecond length, such electrons
may seed the electric breakdown and create sufficiently dense plasma at the
focal region to be detected as an unambiguous effect of the concealed
radioactive material.Comment: 27 pages, 10 figure
Bound states due to a strong interaction supported by a curved surface
We study the Schr\"odinger operator in
with a interaction supported by an infinite non-planar
surface which is smooth, admits a global normal parameterization with
a uniformly elliptic metric. We show that if is asymptotically planar
in a suitable sense and is sufficiently large this operator has a
non-empty discrete spectrum and derive an asymptotic expansion of the
eigenvalues in terms of a ``two-dimensional'' comparison operator determined by
the geometry of the surface . [A revised version, to appear in J. Phys.
A]Comment: LaTeX 2e, 21 page
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