High Efficiency Power Combining of Ka-Band TWTs for High Data Rate Communications

Future NASA deep space exploration missions are expected in some cases to require telecommunication systems capable of operating at very high data rates (potentially 1 Gbps or more) for the transmission back to Earth of large volumes of scientific data, which means high frequency transmitters with large bandwidth. Among the Ka band frequencies of interest are the present 500 MHz Deep Space Network (DSN) band of 31.8 to 32.3 GHz and a broader band at 37-38 GHz allocated for space science [1]. The large distances and use of practical antenna sizes dictate the need for high transmitter power of up to 1 kW or more. High electrical efficiency is also a requirement. The approach investigated by NASA GRC is a novel wave guide power combiner architecture based on a hybrid magic-T junction for combining the power output from multiple TWTs [1,2]. This architecture was successfully demonstrated and is capable of both high efficiency (90-95%, depending on frequency) and high data rate transmission (up to 622 Mbps) in a two-way power combiner circuit for two different pairs of Ka band TWTs at two different frequency bands. One pair of TWTs, tested over a frequency range of 29.1 to 29.6 GHz, consisted of two 110-115W TWTs previously used in uplink data transmission evaluation terminals in the NASA Advanced Communications Technology Satellite (ACTS) program [1,2]. The second pair was two 100W TWTs (Boeing 999H) designed for high efficiency operation (greater than 55%) over the DSN frequency band of 31.8 to 32.3 GHz [3]. The presentation will provide a qualitative description of the wave guide circuit, results for power combining and data transmission measurements, and results of computer modeling of the magic-T and alternative hybrid junctions for improvements in efficiency and power handling capability. The power combiner results presented here are relevant not only to NASA deep space exploration missions, but also to other U.S. Government agency programs

Somatosensory processing in neurodevelopmental disorders

The purpose of this article is to review the role of somatosensory perception in typical development, its aberration in a range of neurodevelopmental disorders, and the potential relations between tactile processing abnormalities and central features of each disorder such as motor, communication, and social development. Neurodevelopmental disorders that represent a range of symptoms and etiologies, and for which multiple peer-reviewed articles on somatosensory differences have been published, were chosen to include in the review. Relevant studies in animal models, as well as conditions of early sensory deprivation, are also included. Somatosensory processing plays an important, yet often overlooked, role in typical development and is aberrant in various neurodevelopmental disorders. This is demonstrated in studies of behavior, sensory thresholds, neuroanatomy, and neurophysiology in samples of children with Fragile X syndrome, autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), and cerebral palsy (CP). Impaired somatosensory processing is found in a range of neurodevelopmental disorders and is associated with deficits in communication, motor ability, and social skills in these disorders. Given the central role of touch in early development, both experimental and clinical approaches should take into consideration the role of somatosensory processing in the etiology and treatment of neurodevelopmental disorders

Enhanced Growth and Osteogenic Differentiation of Human Osteoblast-Like Cells on Boron-Doped Nanocrystalline Diamond Thin Films

Intrinsic nanocrystalline diamond (NCD) films have been proven to be promising substrates for the adhesion, growth and osteogenic differentiation of bone-derived cells. To understand the role of various degrees of doping (semiconducting to metallic-like), the NCD films were deposited on silicon substrates by a microwave plasma-enhanced CVD process and their boron doping was achieved by adding trimethylboron to the CH4:H2 gas mixture, the B∶C ratio was 133, 1000 and 6700 ppm. The room temperature electrical resistivity of the films decreased from >10 MΩ (undoped films) to 55 kΩ, 0.6 kΩ, and 0.3 kΩ (doped films with 133, 1000 and 6700 ppm of B, respectively). The increase in the number of human osteoblast-like MG 63 cells in 7-day-old cultures on NCD films was most apparent on the NCD films doped with 133 and 1000 ppm of B (153,000±14,000 and 152,000±10,000 cells/cm2, respectively, compared to 113,000±10,000 cells/cm2 on undoped NCD films). As measured by ELISA per mg of total protein, the cells on NCD with 133 and 1000 ppm of B also contained the highest concentrations of collagen I and alkaline phosphatase, respectively. On the NCD films with 6700 ppm of B, the cells contained the highest concentration of focal adhesion protein vinculin, and the highest amount of collagen I was adsorbed. The concentration of osteocalcin also increased with increasing level of B doping. The cell viability on all tested NCD films was almost 100%. Measurements of the concentration of ICAM-1, i.e. an immunoglobuline adhesion molecule binding inflammatory cells, suggested that the cells on the NCD films did not undergo significant immune activation. Thus, the potential of NCD films for bone tissue regeneration can be further enhanced and tailored by B doping and that B doping up to metallic-like levels is not detrimental for cells

An overview of tissue engineering approaches for management of spinal cord injuries

Severe spinal cord injury (SCI) leads to devastating neurological deficits and disabilities, which necessitates spending a great deal of health budget for psychological and healthcare problems of these patients and their relatives. This justifies the cost of research into the new modalities for treatment of spinal cord injuries, even in developing countries. Apart from surgical management and nerve grafting, several other approaches have been adopted for management of this condition including pharmacologic and gene therapy, cell therapy, and use of different cell-free or cell-seeded bioscaffolds. In current paper, the recent developments for therapeutic delivery of stem and non-stem cells to the site of injury, and application of cell-free and cell-seeded natural and synthetic scaffolds have been reviewed

Quality analysis of functioning of the iButton sensors concerning their suitability in environmental studies

Pomiary temperatury powietrza w badaniach środowiskowych są zazwyczaj standardowymi działaniami, ale często stwarzają wiele problemów. Główną bolączką wszystkich pomiarów terenowych jest problem z zasilaniem. W pracy przedstawiono przykłady wykorzystania czujników iButton®Dallas, jako alternatywę dla drogiej, energetycznie zależnej aparatury. Wstępne testy wykazały ich wysoką czułość, dokładność i niezawodność. Czujniki zostały wykorzystane w kilku badaniach terenowych: analizie pionowego gradientu temperatury, badaniach nad rozkładem temperatury powietrza w makroprzestrzeni (ok. 10ha), analizie topoklimatycznej na powierzchni około 50 km2. Autonomiczność energetyczna czujników pomogła w pełni wykorzystać ich inne zalety, jak niewielki rozmiar i możliwość bezproblemowego umieszczenia w wybranych punktach. Uzyskane w ten sposób wyniki pokazały szereg ważnych informacji o rozkładzie temperatury, których w standardowych warunkach obserwacji nie można byłoby uczynić. W związku z tym, zdaniem autorów, czujniki iButton®Dallas są dobrą alternatywą dla wszelkiego rodzaju obserwacji terenowych, których celem jest sprawdzenie stanu cieplnego atmosfery i innych środowisk, np.: gleby lub wody.The measurements of air temperature in the environmental studies are usually a standard action, but often pose a lot of problems. The main trouble all field measurements is the problem of power supply. The paper presents an alternative to expensive and subsidiary equipment in the form of iButton®Dallas. The preliminary tests have shown their very high sensitivity, accuracy and reliability. The sensors have been used in several field studies, from the vertical point system, trough the distribution of microtherm conditions within 10 hectares, to the topoclimatic analysis an area of about 50 km2. Energy autonomous sensor allowed full use of the advantage of another that was small in size and place them with no problem at selected points. The measurements were obtained by a number of important information about the distribution of temperature, which in standard conditions of observation would be impossible to do so iButton®Dallas sensors are therefore a good alternative for all kinds of environmental observations, aimed at verification of thermal condition of the atmosphere and other backgrounds, for example soil or water

Stratification of thermo-hygrometric conditions of a grassy ecosystem in the open area and on the edge of a forest

Praca jest analizą mikroklimatu obszaru łąkowego, w obrębie Stacji Dydaktyczno-Badawczej w Bałdach, zlokalizowanej na Pojezierzu Olsztyńskim. Badania zrealizowano w oparciu o zasoby użytków zielonych stacji, przeznaczane przede wszystkim na wypas bydła w okresie od pierwszej dekady maja do końca października. W celu sprawdzenia wskaźników termicznych i wilgotnościowych wykonano obserwacje temperatury powietrza i wilgotności względnej na 6-ciu wysokościach: 0,05 m; 0,5 m; 1,0 m; 1,5 m; 2,0 m; 3,0 m; 4,0 m w dwóch wybranych punktach. Zostały one zlokalizowane nad ekosystemem trawiastym w terenie otwartym i na granicy z lasem. Dane o temperaturze powie-trza były zapisywane z częstotliwością 5-cio minutową w dwóch seriach pomiarowych: wiosną i jesienią, każdorazowo przez pięć dni. W wyniku pomiarów otrzymano unikalne rozkłady dobowe i godzinowe na poszczególnych wysokościach, które świadczą o znacznym zróżnicowaniu mikroklimatycznym poszczególnych punktów.The work is the analysis of the microclimatic conditions over the grassland ecosystem within the Teaching and Research Station in Bałdy, located in the Olsztyn Lake District. The study was carried out based on the resources of grassland station, devoted primarily to cattle grazing in the period from the first decade of May to end of October. In order to verify the thermal and moisture indicators, observations were made of air temperature and relative humidity for six heights: 0.05 m; 0.5 m; 1.0 m; 1.5 m; 2.0 m; 3.0 m; 4.0 m at the two selected points. They were located above the grassland ecosystem in the open area and at the border of the forest. Data on air temperature were recorded at a frequency of 5-minute measurements in two series : spring and autumn, each time for five days. As a result of the measurements, unique schedule of daily and hourly values at various altitudes were obtained. They show that the microclimates of the individual points are clearly differentiated

Modeling surface fluxes over a sparse vegetation

In this paper some of aspects in modeling over sparse vegetation using the Land-Air Parameterization Scheme (LAPS), including an approach in calculating the turbulent transfer coefficient using “K-theory” inside a sparse vegetation canopy, were considered. For this purpose, the scheme was run for different sparse agricultural cultivars, i.e., apple orchard, winter wheat and soybean crops, at different sites. The modeled values for surface fluxes, canopy temperature and soil moisture content, were compared with observations. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: Impacts, adaptation and mitigation