7,820 research outputs found
Optimizing an array of antennas for cellular coverage from a high altitude platform
In a wireless communications network served by a high altitude platform (HAP) the cochannel interference is a function of the antenna beamwidth, angular separation and. sidelobe level. At the millimeter wave frequencies proposed for HAPs, an array of aperture type antennas on the platform is a practicable solution for serving the cells. We present a method for predicting cochannel interference based on curve-fit approximations for radiation patterns of elliptic beams which illuminate cell edges with optimum power, and a means of estimating optimum beamwidths for each cell of a regular hexagonal layout. The method is then applied to a 121 cell architecture. Where sidelobes are modeled As a flat floor at 40-dB below peak directivity, a cell cluster size of four yields carrier-to-interference ratios (CIRs), which vary from 15 dB at cell edges to 27 dB at cell centers. On adopting a cluster size of seven, these figures increase, respectively, to 19 and 30 dB. On reducing the sidelobe level, the. improvement in CIR can be quantified. The method also readily allows for regions of overlapping channel coverage to be shown
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An Extended Culture System that Supports Human Primordial Germ Cell-like Cell Survival and Initiation of DNA Methylation Erasure.
The development of an in vitro system in which human primordial germ cell-like cells (hPGCLCs) are generated from human pluripotent stem cells (hPSCs) has been invaluable to further our understanding of human primordial germ cell (hPGC) specification. However, the means to evaluate the next fundamental steps in germ cell development have not been well established. In this study we describe a two dimensional extended culture system that promotes proliferation of specified hPGCLCs, without reversion to a pluripotent state. We demonstrate that hPGCLCs in extended culture undergo partial epigenetic reprogramming, mirroring events described in hPGCs in vivo, including a genome-wide reduction in DNA methylation and maintenance of depleted H3K9me2. This extended culture system provides a new approach for expanding the number of hPGCLCs for downstream technologies, including transplantation, molecular screening, or possibly the differentiation of hPGCLCs into gametes by in vitro gametogenesis
Self-reported Pleasantness Ratings and Examiner-Coded Defensiveness in Response to Touch in Children with ASD: Effects of Stimulus Material and Bodily Location
Tactile defensiveness, characterized by behavioral hyperresponsiveness and negative emotional responses to touch, is a common manifestation of aberrant sensory processing in autism spectrum disorders (ASD) and other developmental disabilities (DD). Variations in tactile defensiveness with the properties of the stimulus and the bodily site of stimulation have been addressed in adults with self-report of perceived tactile pleasantness, but not in children. We presented three materials (pleasant, unpleasant, social) at three bodily sites and measured both examiner-coded defensiveness and self-reported pleasantness from a group of children with ASD and two comparison groups (one with DD, one with typical development (TD)). The main findings were: 1) children with ASD and DD showed significantly more defensiveness reactions and lower pleasantness ratings than the TD group, with higher variability, 2) there was a double dissociation for the effects of material and bodily site of stimulation: while bodily site predicted behavioral defensiveness, material predicted pleasantness rating. Additionally, it was noted that 3) the most pleasant material and the social touch conditions best distinguished ASD and DD from TD on defensiveness, and 4) within the ASD group, social impairment and defensiveness in bodily sites associated with social touch were positively correlated, suggesting a clinically relevant distinction between social and discriminative touch in ASD
A Rapid Flexible Method for Determining Bile Lipids
A rapid flexible method has been developed for the quantitative determination of bile lipids In gallbladder and hepatic bile and duodenal aspirates. Quantification of bile salts involves separation of bile salt conjugates from one another and other bile lipids by thin layer chromatography. The separated salts are determined using 3-hydroxysteroid dehydrogenase and gas liquid chromatography. Cholesterol is determined in petroleum ether extracts of saponified bile by application of the Lieberman-Burchard reaction. Phospholipid phosphorus is determined in purified bile lipid extracts by oxidation followed by application of Bartlett\u27s modification of the Fiske- SubbaRow method
Pola Komunikasi Pemimpin Organisasi Dalam Meningkatkan Motivasi Kerja Anggota Di LPM (Lembaga Pers Mahasiswa) Inovasi Unsrat
Penelitian ini dengan judul Pola Komunikasi Pemimpin Organisasi Dalam Meningkatkan Motivasi Kerja Anggota Di LPM (lembaga pers mahasiswa) Inovasi Unsrat, dengan focus penelitian adalah : Bagaimana komunikasi pemimpin organisasi dalam aspek orientasi kerja. Kemudian tentang bagaimana komunikasi pemimpin organisasi dalam aspek orientasi hubungan. Dan juga bagaimana komunikasi pemimpin organisasi dalam aspek keefektifan. Penelitian ini menggunakan pendekatan metode kualitatif sebagai prosedur penelitian yang menghasilkan data deskriptif berupa kata-kata atau lisan dari orang-orang dan perilaku yang dapat diamati. Teori yang digunakan dalam penelitian ini adalah teori Reddin, mendapatkan hasil penelitian sebagai berikut : (1). Aspek Orientasi-Kerja. Pemimpin Organisasi di LPM Inovasi Unsrat memberikan pemahaman kepada anggota agar dapat mengerti tugas yang diberikan, serta motivasi yang dapat membuat anggota menjadi giat bekerja. Anggota juga berusaha untuk memahami dan termotivasi agar dapat bekerja dengan baik. Komunikasi yang dilakukan dalam meningkatkan motivasi kerja anggota adalah dengan menggunakan komunikasi kelompok medium group yaitu komunikasi dalam kelompok sedang lebih mudah karena dapat diorganisir dengan baik dan terarah, misalnya komunikasi antara satu bidang dengan bidang yang lain dalam organisasi. (2) Aspek Orientasi-Hubungan. Pemimpin organisasi selalu menciptakan hubungan yang baik dengan anggota, begitupun sebaliknya dengan anggota. Komunikasi antara pemimpin dan anggota dalam menciptakan hubungan yang baik dalam organisasi yaitu dengan menggunakan komunikasi antar personal yaitu komunikasi yang terjadi antar komunikator dengan komunikan secara langsung dengan cara berhadapan muka atau tidak. Komunikasi seperti ini lebih efektif karena kedua belah pihak saling melancarkan komunikasinya dan dengan feedback keduanya melaksanakan fungsi masing-masing. Untuk itu pemimpin harus mampu menyediakan waktu untuk dapat berbincang dengan para anggota, sekaligus mengatasi kendala-kendala yang menjadi pemicu keterlambatan dalam penyelesaian tugas. Hal ini juga akan memunculkan berbagai tanggapan ataupun masukkan dari para anggota, yang harus diterima oleh pemimpin organisasi. (3) Aspek Keefektifan. Setiap tugas yang diberikan tidak selalu dapat diselesaikan sesuai target dan tepat waktu, namun pemimpin selalu berusaha untuk mengupayakan agar pencapaian produksi seperti pembuatan majalah tahunan dapat terselesaikan dengan baik dan tepat waktu sesuai deadline. Tidak bisa efektif juga karena kendala yang dihadapi oleh organisasi yang menjadi faktor utama yaitu dana. Pencairan dana yang diproses melalui pengelola Gedung PKM Unsrat, bisa diproses cukup lama, karena pengecekan dilakukan dengan prosedur-prosedur yang telah ditetapkan
Detection limits of organic compounds achievable with intense, short-pulse lasers
Many organic molecules have strong absorption bands which can be accessed by ultraviolet short pulse lasers to produce efficient ionization. This resonant multiphoton ionization scheme has already been exploited as an ionization source in time-of-flight mass spectrometers used for environmental trace analysis. In the present work we quantify the ultimate potential of this technique by measuring absolute ion yields produced from the interaction of 267 nm femtosecond laser pulses with the organic molecules indole and toluene, and gases Xe, N2 and O2. Using multiphoton ionization cross sections extracted from these results, we show that the laser pulse parameters required for real-time detection of aromatic molecules at concentrations of one part per trillion in air and a limit of detection of a few attomoles are achievable with presently available commercial laser systems. The potential applications for the analysis of human breath, blood and tissue samples are discussed
Simulation of tillage systems impact on soil biophysical properties using the SALUS model
A sustainable land management has been defined as the management system that allows for production, while minimizing risk, maintaining quality of soil and water. Tillage systems can significantly decrease soil carbon storage and influence the soil environment of a crop. Crop growth models can be useful tools in evaluating the impact of different tillage systems on soil biophysical properties and on the growth and final yield of the crops. The objectives of this paper were i) to illustrate the SALUS model and its tillage component; ii) to evaluate the effects of different tillage systems on water infiltration and time to ponding, iii) to simulate the effect of tillage systems on some soil biophysical properties. The SALUS (System Approach to Land Use Sustainability) model is designed to simulate continuous crop, soil, water and nutrient conditions under different tillage and crop residues management strategies for multiple years. Predictions of changes in surface residue, bulk density, runoff, drainage and evaporation were consistent with expected behaviours of these parameters as described in the literature. The experiment to estimate the time to ponding curve under different tillage system confirmed the theory and showed the beneficial effects of the residue on soil surface with respect to water infiltration. It also showed that the no-tillage system is a more appropriate system to adopt in areas characterized by high intensity rainfal
Testing limits to airflow perturbation device (APD) measurements
<p>Abstract</p> <p>Background</p> <p>The Airflow Perturbation Device (APD) is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated.</p> <p>Method</p> <p>Ten subjects between the ages of 18 and 35 were tested for each station in the experiment. The first station involved testing the effects of leaks of known sizes on APD measurements. The second station tested the use of an oronasal mask used in conjunction with the APD during nose and mouth breathing. The third station tested the effects of two different resistances added in series with the APD mouthpiece. The fourth station tested the usage of a flexible ventilator tube in conjunction with the APD.</p> <p>Results</p> <p>All leaks reduced APD resistance measurement values. Leaks represented by two 3.2 mm diameter tubes reduced measured resistance by about 10% (4.2 cmH<sub>2</sub>O·sec/L for control and 3.9 cm H<sub>2</sub>O·sec/L for the leak). This was not statistically significant. Larger leaks given by 4.8 and 6.4 mm tubes reduced measurements significantly (3.4 and 3.0 cm cmH<sub>2</sub>O·sec/L, respectively). Mouth resistance measured with a cardboard mouthpiece gave an APD measurement of 4.2 cm H<sub>2</sub>O·sec/L and mouth resistance measured with an oronasal mask was 4.5 cm H<sub>2</sub>O·sec/L; the two were not significantly different. Nose resistance measured with the oronasal mask was 7.6 cm H<sub>2</sub>O·sec/L. Adding airflow resistances of 1.12 and 2.10 cm H<sub>2</sub>O·sec/L to the breathing circuit between the mouth and APD yielded respiratory resistance values higher than the control by 0.7 and 2.0 cm H<sub>2</sub>O·sec/L. Although breathing through a 52 cm length of flexible ventilator tubing reduced the APD measurement from 4.0 cm H<sub>2</sub>O·sec/L for the control to 3.6 cm H<sub>2</sub>O·sec/L for the tube, the difference was not statistically significant.</p> <p>Conclusion</p> <p>The APD can be adapted for use in ventilated, unconscious, and uncooperative patients with use of a ventilator tube and an oronasal mask without significantly affecting measurements. Adding a resistance in series with the APD mouthpiece has an additive effect on resistance measurements, and can be used for qualitative calibration. A leak size of at least the equivalent of two 3.2 mm diameter tubes can be tolerated without significantly affecting APD measurements.</p
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Supporting Data: Controls on Sediment Bed Erodibility in a Muddy, Partially-Mixed Tidal Estuary, York River, Virginia
Dataset consists of all sampling cruises with data that were analyzed and used in the statistical modeling associated with Wright (2021) and Wright et al. (2022). Each cruise folder includes erodibility data that was analyzed using a Gust Microcosm along with sediment and water column characteristics
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