3,253 research outputs found
Interactions Between Convective Storms and Their Environment
The ways in which intense convective storms interact with their environment are considered for a number of specific severe storm situations. A physical model of subcloud wind fields and vertical wind profiles was developed to explain the often observed intensification of convective storms that move along or across thermal boundaries. A number of special, unusually dense, data sets were used to substantiate features of the model. GOES imagery was used in conjunction with objectively analyzed surface wind data to develop a nowcast technique that might be used to identify specific storm cells likely to become tornadic. It was shown that circulations associated with organized meso-alpha and meso-beta scale storm complexes may, on occasion, strongly modify tropospheric thermodynamic patterns and flow fields
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Black and minority ethnic trainees’ experiences of physical education initial teacher training
The official published version can be accessed at the link below.This report draws together the findings of research that aimed to explore black and minority ethnic (BME) trainees’ experiences of Physical Education (PE) initial teacher training (ITT). Although the numbers of BME trainees opting to enter teaching have improved considerably over the last few years, PE remains one of three specific subject areas where they remain significantly under-represented. Current figures suggest that PE attracts approximately 3% of trainees from BME backgrounds, compared with 11% for new entrants into teaching overall. The relative lack of success in attracting BME trainees into PE teaching compared to other subject areas suggests that the subculture of the subject may be a compounding factor. Over the last decade or so, a number of studies have explored the impact of ethnicity on teachers’ professional socialisation and their experiences as teachers in school, but none have focused on experiences within specific subject cultures. The centrality of the body in PE, and the link between this and the perceived low status of the subject, are influencing factors highlighted in the broader literature, including sports studies. For example, research exploring racism and the under-representation of BME participants in sport has highlighted the prevalence of stereotypical attitudes about their physicality and abilities held by coaches, administrators and spectators. Other research has suggested that some minority ethnic groups favour higher status, better paid, careers in areas such as law or medicine rather than teaching. As yet, there has been little attention to ‘race’ and ethnicity within PEITT, although studies have shown the impact of gender on trainees’ developing professional identities, and how teachers’ gendered bodies are important ‘tools’ of their work. In addition, there has been little research that has acknowledged trainees’ multiple identities, or the complex ways in which ‘race’, ethnicity, class and gender and other identity markers intersect to impact on the professional socialisation process. The research on which this report is based sought to fill some of these gaps in our understandings of BME trainees’ experiences of PEITT, and to identify strategies that might help in their recruitment and retention in the longer term. The research was funded through a small Recruitment and Retention Challenge Grant from the Teacher Development Agency (TDA). These grants form part of the TDA’s wider policy agenda to widen the diversity of new intakes opting into teaching. Higher education institutions have been encouraged, through targets and financial support and incentives, to develop specific strategies aimed at widening the diversity of their cohorts. Examples of such strategies include the provision of specialist admission help for BME prospective trainees; opportunities to gain experience in schools; open days and ‘taster’ events; advertising in the ethnic minority media, and the development of good practice guides and staff training to help ITT providers address issues of ‘race’ and ethnicity. 5 The impetus for this research resulted, in part, from presentations and discussions at a one day PEITT Network1 staff seminar on diversity held in October, 2007. The quantitative research conducted by the Association for Physical Education (AfPE) and the Ethnic Minority Foundation (EMF) presented here, showed the extent of the national under-representation of BME students in PEITT. Although the day focused on addressing reasons for BME under representation and strategies that might be used for improving recruitment, we felt it was also important to learn about the qualitative experiences of trainees that have been attracted into PEITT. Understanding the experiences of our current BME trainees might offer useful insights into how we might recruit and retain future such trainees. Our choice of qualitative research was supported by a national study published shortly after the network day, investigating the links between gender, ethnicity and degree attainment (Higher Education Academy, HEA, 2008), which specifically calls for further qualitative studies of students’ experiences of different subject areas.Funding from the Training and Development Agency (TDA
The swept angle retarding mass spectrometer: Initial results from the Michigan auroral probe sounding rocket
Data from a sounding rocket flight of the swept angle retarding ion mass spectrometer (SARIMS) are presented to demonstrate the capability of the instrument to make measurements of thermal ions which are differential in angle, energy, and mass. The SARIMS was flown on the Michigan auroral probe over regions characterized first by discrete auroral arcs and later by diffuse precipitation. The instrument measured the temperature, densities, and flow velocities of the ions NO(+) and O(+). Measured NO(+) densities ranged from 10 to the 5th power up to 3 x 10 to the 5th power ions/cu cm, while the measured O(+) densities were a factor of 5-10 less. Ion temperatures ranged from 0.15 up to 0.33 eV. Eastward ion flows approximately 0.5 km/sec were measured near the arcs, and the observed flow magnitude decreased markedly inside the arcs
Pilots' use of a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier operations. Volume 1: Methodology, summary and conclusions
Pilots' use of and responses to a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier line operations are described in Volume 1. TCAS 2 monitors the positions of nearby aircraft by means of transponder interrogation, and it commands a climb or descent when conflicting aircraft are projected to reach an unsafe closest point-of-approach within 20 to 25 seconds. A different level of information about the location of other air traffic was presented to each of three groups of flight crews during their execution of eight simulated air carrier flights. A fourth group of pilots flew the same segments without TCAS 2 equipment. Traffic conflicts were generated at intervals during the flights; many of the conflict aircraft were visible to the flight crews. The TCAS equipment successfully ameliorated the seriousness of all conflicts; three of four non-TCAS crews had hazardous encounters. Response times to TCAS maneuver commands did not differ as a function of the amount of information provided, nor did response accuracy. Differences in flight experience did not appear to contribute to the small performance differences observed. Pilots used the displays of conflicting traffic to maneuver to avoid unseen traffic before maneuver advisories were issued by the TCAS equipment. The results indicate: (1) that pilots utilize TCAS effectively within the response times allocated by the TCAS logic, and (2) that TCAS 2 is an effective collision avoidance device. Volume II contains the appendices referenced in Volume I, providing details of the experiment and the results, and the text of two reports written in support of the program
Report from magnetospheric science
By the early 1990s, magnetospheric physics will have progressed primarily through observations made from Explorer-class spacecraft, sounding rockets, ground based facilities, and shuttle based experiments. The global geospace science (GGS) element of the International Solar Terrestrial Physics program, when combined with contributions to the ESA Cluster mission and ground based and computer modeling programs, will form the basis for a major U.S. initiative in magnetospheric physics. The scientific objectives of the GGS program involve the study of energy transport throughout geospace. The Cluster mission will investigate turbulence and boundary phenomena in geospace, particularly at high latitudes on the dayside and in the region of the neutral sheet at geocentric distances of about 20 earth radii on the night side of the earth. The current state of knowledge is reviewed and the goals of these missions are briefly discussed
Pilots' use of a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier operations. Volume 2: Appendices
Pilots' use of and responses to a traffic alert and collision-avoidance system (TCAS 2) in simulated air carrier line operations are discribed in Volume 1. TCAS 2 monitors the positions of nearby aircraft by means of transponder interrogation, and it commands a climb or descent which conflicting aircraft are projected to reach an unsafe closest point-of-approach within 20 to 25 seconds. A different level of information about the location of other air traffic was presented to each of three groups of flight crews during their execution of eight simulated air carrier flights. A fourth group of pilots flew the same segments without TCAS 2 equipment. Traffic conflicts were generated at intervals during the flights; many of the conflict aircraft were visible to the flight crews. The TCAS equipment successfully ameliorated the seriousness of all conflicts; three of four non-TCAS crews had hazardous encounters. Response times to TCAS maneuver commands did not differ as a function of the amount of information provided, nor did response accuracy. Differences in flight experience did not appear to contribute to the small performance differences observed. Pilots used the displays of conflicting traffic to maneuver to avoid unseen traffic before maneuver advisories were issued by the TCAS equipment. The results indicate: (1) that pilots utilize TCAS effectively within the response times allocated by the TCAS logic, and (2) that TCAS 2 is an effective collision avoidance device. Volume 2 contains the appendices referenced in Volume 1, providing details of the experiment and the results, and the text of two reports written in support of the program
Instrument manual for the retarding ion mass spectrometer on Dynamics Explorer-1
The retarding ion mass spectrometer (RIMS) for Dynamics Explorer-1 is an instrument designed to measure the details of the thermal plasma distribution. It combines the ion temperature determining capability of the retarding potential analyzer with the compositional capabilities of the mass spectrometer and adds multiple sensor heads to sample all directions relative to the spacecraft ram direction. This manual provides a functional description of the RIMS, the instrument calibration, and a description of the commands which can be stored in the instrument logic to control its operation
Blood vessel anastomosis is spatially regulated by Flt1 during angiogenesis
Blood vessel formation is essential for vertebrate development and is primarily achieved by angiogenesis – endothelial cell sprouting from pre-existing vessels. Vessel networks expand when sprouts form new connections, a process whose regulation is poorly understood. Here, we show that vessel anastomosis is spatially regulated by Flt1 (VEGFR1), a VEGFA receptor that acts as a decoy receptor. In vivo, expanding vessel networks favor interactions with Flt1 mutant mouse endothelial cells. Live imaging in human endothelial cells in vitro revealed that stable connections are preceded by transient contacts from extending sprouts, suggesting sampling of potential target sites, and lowered Flt1 levels reduced transient contacts and increased VEGFA signaling. Endothelial cells at target sites with reduced Flt1 and/or elevated protrusive activity were more likely to form stable connections with incoming sprouts. Target cells with reduced membrane-localized Flt1 (mFlt1), but not soluble Flt1, recapitulated the bias towards stable connections, suggesting that relative mFlt1 expression spatially influences the selection of stable connections. Thus, sprout anastomosis parameters are regulated by VEGFA signaling, and stable connections are spatially regulated by endothelial cell-intrinsic modulation of mFlt1, suggesting new ways to manipulate vessel network formation
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