46,577 research outputs found
New meter probes provide protection from high current power sources at potentials up to 600 volts
Meter probes incorporating integral fuse holder which contains limitation fuse of 600 V, 5A, with interruption rating of 50,000 KVA. provide required protection and minimize danger incurred by defective or improperly operated meter
Technique for extending the frequency range of digital dividers
A technique for extending the frequency range of a presettable digital divider is described. The conventional digital divider consists of several counter stages with the count of each stage compared to a preselected number. When the counts for all stages are equal to the preselected numbers, an output pulse is generated and all stages are reset. For high input frequencies, the least significant stage of the divider has to be reset in a very short time. This limits the frequency that can be handled by the conventional digital divider. This invention provides a technique in which the second least significant and higher stages are reset and the least significant stage is permitted to free-run. Hence, the time in which the reset operation can be performed is increased thereby extending the frequency range of the divider
Killing Spinors for the Bosonic String
We obtain the effective action for the bosonic string with arbitrary
Yang-Mills fields, up to the \alpha' order, in general dimensions. The form of
the action is determined by the requirement that the action admit well-defined
Killing spinor equations, whose projected integrability conditions give rise to
the full set of equations of motion. The success of the construction suggests
that the hidden "pseudo-supersymmetry" associated with the Killing spinor
equations may be a property of the bosonic string itself.Comment: 9 page
The MS Symptom and Impact Diary (MSSID): psychometric evaluation of a new instrument to measure the day to day impact of multiple sclerosis
OBJECTIVES: This study aimed to develop further a diary originally devised to measure the impact of multiple
sclerosis (MS) as part of a cost utility study of beta interferon, and to evaluate its reliability, validity, and
responsiveness in an outpatient sample of people with MS.
METHODS: The original diary was further developed using qualitative and quantitative methods to ensure
that it addressed the views of people with MS. The psychometric properties of the MS Symptom and Impact
Diary (MSSID) were evaluated in a sample of 77 people who completed the MSSID daily for 12 weeks.
Internal and test–retest reliability, discriminant and convergent validity, and responsiveness were assessed
using traditional psychometric methods.
RESULTS: The MSSID formed three, internally consistent scales that measured mobility, fatigue, and the
overall impact of MS. The test–retest reliability of the mobility scale was adequate for individual
comparisons (ICC.0.90) and the fatigue and overall impact scales were adequate for group comparisons
(ICC.0.70). The MSSID was able to distinguish between clinical groups depending on clinical course,
indoor ambulation status, and relapse status. It demonstrated associations with other single point
instruments in the expected direction. Compared with single point instruments, its responsiveness was
similar or better, especially in detecting short term improvements in functioning.
CONCLUSIONS: The MSSID may provide a useful complement to currently available instruments to measure
the outcomes of MS within clinical trials. Further research is needed to explore its feasibility in the context
of a randomised controlled trial and its utility for clinicians
The 125 GeV Higgs and Electroweak Phase Transition Model Classes
Recently, the ATLAS and CMS detectors have discovered a bosonic particle
which, to a reasonable degree of statistical uncertainty, fits the profile of
the Standard Model Higgs. One obvious implication is that models which predict
a significant departure from Standard Model phenomenology, such as large exotic
(e.g., invisible) Higgs decay or mixing with a hidden sector scalar, are
already ruled out. This observation threatens the viability of electroweak
baryogenesis, which favors, for example, a lighter Higgs and a Higgs coupled to
or mixed with light scalars. To assess the broad impact of these constraints,
we propose a scheme for classifying models of the electroweak phase transition
and impose constraints on a class-by-class basis. We find that models, such as
the MSSM, which rely on thermal loop effects are severely constrained by the
measurement of a 125 GeV Higgs. Models which rely on tree-level effects from a
light singlet are also restricted by invisible decay and mixing constraints.
Moreover, we find that the parametric region favored by electroweak
baryogenesis often coincides with an enhanced symmetry point with a distinctive
phenomenological character. In particular, enhancements arising through an
approximate continuous symmetry are phenomenologically disfavored, in contrast
with enhancements from discrete symmetries. We also comment on the excess of
diphoton events observed by ATLAS and CMS. We note that although Higgs portal
models can accommodate both enhanced diphoton decay and a strongly first order
electroweak phase transition, the former favors a negative Higgs portal
coupling whereas the latter favors a positive one, and therefore these two
constraints are at tension with one another.Comment: 35 pages, 7 figure
On the Existence and Interpretation of the "Unit Root" in U.S. GNP
In this paper, we assess the degree to which four of the most commonly used models of risky decision making can explain the choices individuals make when faced with risky prospects. To make this assessment, we use experimental evidence for two random samples of young adults. Using a robust, nonlinear least squares procedure, we estimate a model that is general enough to approximate Kahnenman and Tversky's prospect theory and that for certain parametric values will yield the expected utility model, a subjective expected utility model and a probability-transform model. We find that the four models considered explain the decision-making behavior of the majority of our subjects. Surprisingly, we find that the choice behavior of the largest number of subjects is consistent with a probability-transform model. Such models have only been developed recently and have not been used in applied settings. We find least support for the expected utility model -- the most widely used model of risky decision making.
Are Business Cycles Symmetric?
This note shows that contrary to widespread belief there is little evidence that the business cycle is asymmetric. Using American data for the pre- and post-war periods and data on five other major OECD nations for the post-war period, we are unable to support the hypothesis that contractions are shorter and sharper than expansions. We conclude that there is not much basis for preferring some version of traditional cyclical techniques to more modern statistical methods.
The Changing Cyclical Variability of Economic Activity in the United States
This paper examines the changing cyclical variability of economic activity in the United States. It first shows that the decline in variability since World War II cannot be explained by changes in the composition of economic activity or by the avoidance of financial panics. We then show that increased automatic stabilization by the government, and the increased availability of private credit after World War II combined to stabilize consumption and reduce the variability of aggregate demand. The main argument of the paper holds that greater price rigidity in recent times may have contributed to economic stability by preventing destabilizing deflations and inflations. Empirical evidence is presented to support this proposition.
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