5,057 research outputs found

    Perturbative QCD Corrections to the Soft Pomeron

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    We study the interface between soft and hard QCD at high energy and small momentum transfer. At LHC and SSC energies, we find that a cutoff BFKL equation leads one to expect a measurable perturbative component in traditionally soft processes. We show that the total cross section could become as large as 175 mb (122 mb) and the rho parameter 0.40 (0.25) at the SSC (LHC).Comment: 10 pages, McGill/92--2

    The High Energy Behavior of the Forward Scattering Parameters---An Amplitude Analysis Update

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    Utilizing the most recent experimental data, we reanalyze high energy \pbar p and pp data, using the asymptotic amplitude analysis, under the assumption that we have reached `asymptopia'. This analysis gives strong evidence for a log(s/s0)\log \,(s/s_0) dependence at {\em current} energies and {\em not} log2(s/s0)\log^2 (s/s_0), and also demonstrates that odderons are {\em not} necessary to explain the experimental data.Comment: 7 pages in LaTeX, 4 figures and 5 files, uuencoded in file "sigall.uu

    Sources of the ultraheavy cosmic rays

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    The suggestions that the source abundances of cosmic ray nuclei heavier then Fe differ significantly from Solar System abundances are not well supported by the data without assuming preferential acceleration. The Solar System abundances of Pb and Bi are split into r-, standard s-, and cyclic 8-process components; the apprarent deficiency of Pb seen in the HEAO-3 Heavy Nuclei Experiment data might indicate an absence of Pb from the recycling 8-process

    Curve fits of predicted inviscid stagnation-point radiative heating rates, cooling factors, and shock standoff distances for hyperbolic earth entry

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    Curve-fit formulas are presented for the stagnation-point radiative heating rate, cooling factor, and shock standoff distance for inviscid flow over blunt bodies at conditions corresponding to high-speed earth entry. The data which were curve fitted were calculated by using a technique which utilizes a one-strip integral method and a detailed nongray radiation model to generate a radiatively coupled flow-field solution for air in chemical and local thermodynamic equilibrium. The range of free-stream parameters considered were altitudes from about 55 to 70 km and velocities from about 11 to 16 km.sec. Spherical bodies with nose radii from 30 to 450 cm and elliptical bodies with major-to-minor axis ratios of 2, 4, and 6 were treated. Powerlaw formulas are proposed and a least-squares logarithmic fit is used to evaluate the constants. It is shown that the data can be described in this manner with an average deviation of about 3 percent (or less) and a maximum deviation of about 10 percent (or less). The curve-fit formulas provide an effective and economic means for making preliminary design studies for situations involving high-speed earth entry

    Quality perception in higher education - using SERVQUAL methodology

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    Understanding the student’s perception in higher education goes far beyond student retention. Factors such as satisfaction, motivation and irritability points help not only in a more convergent service planning between the institution’s efforts in the face of student expectation, but also in better learning. The perceived quality is difficult to measure and subjective. This work aims to understand the perceived quality of the student and analyze the SERQUAL model for its application in higher education. The 5 dimensions of the model were correlated with academic pillars and the sub-items of each dimension were expanded, according to previous studies. The research was conducted with 15% of the universe of students from a higher education course, which represents 69 students, from a private institution. The results were validated in a focus group of 5 students using tools such as the Ishikawa diagram and the Interrelationship Diagram. As a result of the application it was diagnosed that students have a higher expectation than the service offered, which results in a perceived negative quality. Points such as ‘parking’ and ‘operational service’, which are not essential characteristics of the educational service, directly impact on the perception of quality and consequently on the student’s satisfaction. As a main result it was noticed that the method points out the problems that most bother the students. They tend to analyze the whole and camouflage items in the face of these stressful stimuli. The method proved to be an ally in the detection of problems of perceived felt quality, but that requires beyond the determination of the data to understand the root cause of the results

    Student satisfaction through an adaptation of the SAM method: an analysis from consumption to post-consumption in higher education degrees

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    The higher education market is experiencing a duality between meeting financial and academic goals. In both perspectives, the search for student/consumer satisfaction is a reality. The methods for measuring student satisfaction, in the Brazilian scenario, are mostly based on marketing metrics, without a real understanding of the students' feelings and perceptions. Given this scenario, the question is whether there is a divergence in perception between the student and the former student and if there is any viable technique capable of measuring these issues. In a quantitative survey, with 256 students, 81 former students, and 47 professors, an adaptation of the SAM (Self-Assessment Manikin) scale was carried out, with reason-emotion humanoids and academic stimuli. The main result is that the SAM is a viable, fast and effective model. It addresses institutional technical issues from a personal perspective. Furthermore, the divergence of perception between the former students and the current students was found.This work was financed by the Project Lab2PT - Landscapes, Heritage and Territory laboratory - UIDB/04509/2020 through FCT - Fundação para a Ciência e a Tecnologia

    Surface Fire to Crown Fire: Fire History in the Taos Valley Watersheds, New Mexico, USA

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    Tree-ring fire scars, tree ages, historical photographs, and historical surveys indicate that, for centuries, fire played different ecological roles across gradients of elevation, forest, and fire regimes in the Taos Valley Watersheds. Historical fire regimes collapsed across the three watersheds by 1899, leaving all sites without fire for at least 119 years. Historical photographs and quaking aspen (Populus tremuloides Michx.) ages indicate that a high-severity fire historically burned at multiple high-elevation subalpine plots in today’s Village of Taos Ski Valley, with large high-severity patches (\u3e640 ha). Low-severity, frequent (9–29-year median interval) surface fires burned on the south aspects in nearby lower elevation dry conifer forests in all watersheds. Fires were associated with drought during the fire year. Widespread fires commonly burned synchronously in multiple watersheds during more severe drought years, preceded by wet years, including fire in all three watersheds in 1664, 1715, and 1842. In contrast, recent local “large” wildfires have only burned within single watersheds and may not be considered large in a historical context. Management to promote repeated low-severity fires and the associated open stand structures is within the historical range of variability in the dry conifer forests of these watersheds. In the high-elevation, subalpine forests, different management approaches are needed, which balance ecological and socioeconomic values while providing public safety

    Targeted Derepression of the Human Immunodeficiency Virus Type 1 Long Terminal Repeat by Pyrrole-Imidazole Polyamides

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    The host factor LSF represses the human immunodeficiency virus type 1 long terminal repeat (LTR) by mediating recruitment of histone deacetylase. We show that pyrrole-imidazole polyamides targeted to the LTR can specifically block LSF binding both in vitro and within cells via direct access to chromatin, resulting in increased LTR expression

    Cellular Origin of Spontaneous Ganglion Cell Spike Activity in Animal Models of Retinitis Pigmentosa

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    Here we review evidence that loss of photoreceptors due to degenerative retinal disease causes an increase in the rate of spontaneous ganglion spike discharge. Information about persistent spike activity is important since it is expected to add noise to the communication between the eye and the brain and thus impact the design and effective use of retinal prosthetics for restoring visual function in patients blinded by disease. Patch-clamp recordings from identified types of ON and OFF retinal ganglion cells in the adult (36–210 d old) rd1 mouse show that the ongoing oscillatory spike activity in both cell types is driven by strong rhythmic synaptic input from presynaptic neurons that is blocked by CNQX. The recurrent synaptic activity may arise in a negative feedback loop between a bipolar cell and an amacrine cell that exhibits resonant behavior and oscillations in membrane potential when the normal balance between excitation and inhibition is disrupted by the absence of photoreceptor input
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