2,064 research outputs found
Subcolumnar Dendritic and Axonal Organization of Spiny Stellate and Star Pyramid Neurons within a Barrel in Rat Somatosensory Cortex
Excitatory neurons at the level of cortical layer 4 in the rodent somatosensory barrel field often display a strong eccentricity in comparison with layer 4 neurons in other cortical regions. In rat, dendritic symmetry of the 2 main excitatory neuronal classes, spiny stellate and star pyramid neurons (SSNs and SPNs), was quantified by an asymmetry index, the dendrite-free angle. We carefully measured shrinkage and analyzed its influence on morphological parameters. SSNs had mostly eccentric morphology, whereas SPNs were nearly radially symmetric. Most asymmetric neurons were located near the barrel border. The axonal projections, analyzed at the level of layer 4, were mostly restricted to a single barrel except for those of 3 interbarrel projection neurons. Comparing voxel representations of dendrites and axon collaterals of the same neuron revealed a close overlap of dendritic and axonal fields, more pronounced in SSNs versus SPNs and considerably stronger in spiny L4 neurons versus extragranular pyramidal cells. These observations suggest that within a barrel dendrites and axons of individual excitatory cells are organized in subcolumns that may confer receptive field properties such as directional selectivity to higher layers, whereas the interbarrel projections challenge our view of barrels as completely independent processors of thalamic inpu
The Active CryoCubeSat Project: System Modeling and Control Design
Utah State University together with the NASA Jet Propulsion Laboratory have been developing new cooling technology for high power CubeSats. This effort has been funded by the NASA Space Technology Mission Directorate in an effort to enable CubeSats with extraordinary thermal control needs for subsystems such as computing, telemetry, or cryogenics and where passive techniques are insufficient. The approach is to use a pumped fluid loop to remove heat from an internal heat exchanger and transport it to an external radiator on the CubeSat. Recently, Utah State has thermal vacuum-tested prototype systems collecting significant amounts of data on the thermodynamics of pumped fluid loops for small spacecraft. This paper presents the model-based thermal feedback and control system design for Utah State’s Active CryoCubeSat prototype. This system is based on a single-phase, two-stage mechanically pumped fluid system, designed to support 6U CubeSat platforms and above. The system modeling was conducted using two different approaches. First, a physical model was derived from the first principle equations, then a system identification was conducted using data collected from the thermal vacuum chamber test of the ACCS system. This paper presents the results and comparison of both models, as well as their limitations in describing the physical behavior of the system. Based on those models, a control system was designed and tuned to achieve a series of thermal requirements for the thermal control of a small cryocooler supporting an infra-red detector at 70 to 120K
Thermal and Radiation Design Considerations for CubeSats in Low Lunar Orbit
NASA\u27s Artemis program is turning the attention back to the Moon. As an example of Artemis I, CubeSats can now be inserted into lunar orbits by ridesharing. Designers must become familiarized with the additional technical challenges of operating far away from the usual low Earth orbit (LEO) condition, especially regarding the lunar radiation and thermal environments. This paper analyzes the thermal environment loads for a spacecraft operating in a low lunar orbit (LLO) at 100km altitude with a fixed nadir-pointing orientation. A simplified thermal model is presented to assess the impact of the surfaces\u27 thermal-optical properties and internal thermal resistances on the maximum dissipation power for 6U and 12U CubeSats at different orbital Beta-Sun angles. The occurrences of Solar eclipses in the next decade are reviewed, as well as the impact on the required heating energy to keep the CubeSats in the safe temperature range during the longest eclipse of the series. The radiation analysis focuses on the total ionization dose received by the spacecraft in LLO compared to LEO. The impact of a full-body radiation shielding approach on the chassis mass is also assessed for different wall thicknesses
Logística integral en mejora de la exportación de espárrago verde orgánico hacia Holanda, desde la empresa Vivadis – Ascope, Trujillo 2018
RESUMEN
La presente investigación se ha desarrollado con el fin de analizar y proponer una
mejora en la logística con el propósito de minimizar los costos de exportación de
esparrago verde orgánico hacia Holanda, desde la empresa VIVADIS – Ascope.
En el desarrollo de esta investigación se ha podido determinar, qué parte del proceso
logístico eleva los costos; identificando que el problema se encuentra en los costos de
exportación, debido a que la empresa emplea para sus exportaciones, el transporte
aéreo, ello afecta directamente en los costos de exportación y muchas veces llegando a
costar más que la materia prima.
Por otro lado, establecer correctamente los costos de exportación se ha vuelto un
factor determinante; ya que de esto depende la rentabilidad de la empresa. Para ello se
debe optar por un tipo de transporte más rentable acorde al tipo de producto o bien a
exportar, considerando de igual modo la seguridad necesaria de este en todo el trayecto
hasta el destino final; además de realizar un contrato adecuado donde beneficie a ambas
partes.
Finalmente, se llega a la conclusión de que VIVADIS debe optar por exportar vía
marítima, teniendo en cuenta que existen contenedores refrigerados especialmente para
este tipo de productos, como consecuencia esto minimizará considerablemente sus
costos. Cumpliendo con los requisitos establecidos para exportar a Holanda y cuidando
que la cadena de frio no se rompa para mantener al espárrago en buen estado.ABSTRACT
The present investigation has been developed with the purpose of analyzing and
proposing an improvement in logistics with the purpose of minimizing the costs of
exporting green asparagus to Holland, from the company VIVADIS - Ascope.
In the development of this research it has been possible to determine, wich part of the
logistic process raises costs; Identifying that the problem lies in export costs, because the
company uses for its exports, air transport, which directly costs export and often is costing
more than the raw material.
On the other side, correctly establishing export costs has become a determining factor;
since the profitability of the company depends on this. To do this, you must choose a
more profitable type of transport according to the type of product or export, considering
the necessary security of the same throughout the journey to the final destination; In
addition to making an adequate contract when it benefits both parties.
Finally, it is concluded that VIVADIS must opt to export to the sea, taking into account
that there are refrigerated containers, especially for this type of products, as a result of
these costs. Complying with the requirements to export to Holland and taking care that the
cold chain does not break to keep the asparagus in good condition
Stimulated Brillouin scattering in tellurite-covered silicon nitride waveguides
Stimulated Brillouin scattering (SBS), a coherent nonlinear effect coupling acoustics and optics, can be used in a wide range of applications such as Brillouin lasers and tunable narrowband RF filtering. Wide adoption of such technologies however, would need a balance of strong Brillouin interaction and low optical loss in a structure compatible with large scale fabrication. Achieving these characteristics in scalable platforms such as silicon and silicon nitride remains a challenge. Here, we investigate a scalable Brillouin platform combining low loss Si3N4 and tellurium oxide (TeO2) exhibiting strong Brillouin response and enhanced acoustic confinement. In this platform we measure a Brillouin gain coefficient of 8.5~m−1W−1, exhibiting a twenty fold improvement over the largest previously reported Brillouin gain in a Si3N4 platform. Further, we demonstrate cladding engineering to control the strength of the Brillouin interaction. We utilized the Brillouin gain and loss resonances in this waveguide for an RF photonic filter with more than 15 dB rejection and 250 MHz linewidth. Finally, we present a pathway by geometric optimization and cladding engineering to a further enhancement of the gain coefficient to 155~m−1W−1, a potential 400 times increase in the Brillouin gain coefficient
Wheat Variety Test Results for South Central Kansas - 2022
South central Kansas is the highest producing wheat region in Kansas. This report summarizes the results of winter wheat variety tests for 2021-2022 in six locations
Stimulated Brillouin scattering in tellurite-covered silicon nitride waveguides
Stimulated Brillouin scattering (SBS), a coherent nonlinear effect coupling
acoustics and optics, can be used in a wide range of applications such as
Brillouin lasers and tunable narrowband RF filtering. Wide adoption of such
technologies however, would need a balance of strong Brillouin interaction and
low optical loss in a structure compatible with large scale fabrication.
Achieving these characteristics in scalable platforms such as silicon and
silicon nitride remains a challenge. Here, we investigate a scalable Brillouin
platform combining low loss SiN and tellurium oxide (TeO)
exhibiting strong Brillouin response and enhanced acoustic confinement. In this
platform we measure a Brillouin gain coefficient of 8.5~mW,
exhibiting a twenty fold improvement over the largest previously reported
Brillouin gain in a SiN platform. Further, we demonstrate cladding
engineering to control the strength of the Brillouin interaction. We utilized
the Brillouin gain and loss resonances in this waveguide for an RF photonic
filter with more than 15 dB rejection and 250 MHz linewidth. Finally, we
present a pathway by geometric optimization and cladding engineering to a
further enhancement of the gain coefficient to 155~mW, a
potential 400 times increase in the Brillouin gain coefficient
European surveillance for enterovirus D68 during the emerging North-American outbreak in 2014
M. Lappalainen, A. Jääskeläinen ja T. Smura ovat työryhmän ESCV-ECDC EV-D68 Study Grp jäseniä.Background: In August and September 2014, unexpected clusters of enterovirus-D68 (EV-D68) infections associated with severe respiratory disease emerged from North-America. In September, the European Centre for Disease Prevention and Control (ECDC) asked European countries to strengthen respiratory sample screening for enterovirus detection and typing in cases with severe respiratory presentations. Objectives: To provide a detailed picture of EV-D68 epidemiology in Europe by conducting a retrospective and prospective laboratory analysis of clinical specimens. Study design: An initiative supported by the European Society for Clinical Virology (ESCV) and ECDC was launched to screen for EV-D68 in respiratory specimens between July 1st and December 1st 2014 in Europe and to sequence the VP1 region of detected viruses for phylogenetic analytic purposes. Results: Forty-two institutes, representing 51 laboratories from 17 European countries, analyzed 17,248 specimens yielding 389 EV-D68 positive samples (2.26%) in 14 countries. The proportion of positive samples ranged between 0 and 25% per country. These infections resulted primarily in mild respiratory disease, mainly detected in young children presenting with wheezing and in immuno-compromised adults. The viruses detected in Europe are genetically very similar to those of the North-American epidemic and the majority (83%) could be assigned to clade B. Except for 3 acute flaccid paralysis (AFP) cases, one death and limited ICU admissions, no severe cases were reported. Conclusions: The European study showed that EV-D68 circulated in Europe during summer and fall of 2014 with a moderate disease burden and different pathogenic profile compared to the North-American epidemic. (C) 2015 The Authors. Published by Elsevier B.V.Peer reviewe
Inhaled Sedation in Patients with COVID-19-Related Acute Respiratory Distress Syndrome: An International Retrospective Study
Background and objectives: The coronavirus disease 2019 (COVID-19) pandemic and the shortage of intravenous sedatives has led to renewed interest in inhaled sedation for patients with acute respiratory distress syndrome (ARDS). We hypothesized that inhaled sedation would be associated with improved clinical outcomes in COVID-19 ARDS patients. Methods: Retrospective international study including mechanically ventilated patients with COVID-19 ARDS who required sedation and were admitted to 10 European and US intensive care units. The primary endpoint of ventilator-free days through day 28 was analyzed using zero-inflated negative binomial regression, before and after adjustment for site, clinically relevant covariates determined according to the univariate results, and propensity score matching. Results: A total of 196 patients were enrolled, 78 of whom died within 28 days. The number of ventilator-free days through day 28 did not differ significantly between the patients who received inhaled sedation for at least 24 h (n = 111) and those who received intravenous sedation only (n = 85), with medians of 0 (interquartile range [IQR] 0–8) and 0 (IQR 0–17), respectively (odds ratio for having zero ventilator-free days through day 28, 1.63, 95% confidence interval [CI], 0.91–2.92, p = 0.10). The incidence rate ratio for the number of ventilator-free days through day 28 if not 0 was 1.13 (95% CI, 0.84–1.52, p = 0.40). Similar results were found after multivariable adjustment and propensity matching. Conclusion: The use of inhaled sedation in COVID-19 ARDS was not associated with the number of ventilator-free days through day 28.
Keywords:
coronavirus disease 2019; acute respiratory distress syndrome; inhaled sedation; sevoflurane; isofluran
IVOA Recommendation: Spectrum Data Model 1.1
We present a data model describing the structure of spectrophotometric
datasets with spectral and temporal coordinates and associated metadata. This
data model may be used to represent spectra, time series data, segments of SED
(Spectral Energy Distributions) and other spectral or temporal associations.Comment: http://www.ivoa.ne
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