11,274 research outputs found
Flight simulator for hypersonic vehicle and a study of NASP handling qualities
The research goal of the Human-Machine Systems Engineering Group was to study the existing handling quality studies in aircraft with sonic to supersonic speeds and power in order to understand information requirements needed for a hypersonic vehicle flight simulator. This goal falls within the NASA task statements: (1) develop flight simulator for hypersonic vehicle; (2) study NASP handling qualities; and (3) study effects of flexibility on handling qualities and on control system performance. Following the above statement of work, the group has developed three research strategies. These are: (1) to study existing handling quality studies and the associated aircraft and develop flight simulation data characterization; (2) to develop a profile for flight simulation data acquisition based on objective statement no. 1 above; and (3) to develop a simulator and an embedded expert system platform which can be used in handling quality experiments for hypersonic aircraft/flight simulation training
MANDATORY VERSUS VOLUNTARY PRICE REPORTING: AN EMPIRICAL INVESTIGATION OF THE MARKET TRANSPARENCY CONTROVERSY
The ability of the former voluntary price reporting system to generate market transparency in U.S. livestock markets was called into question by producer groups and academic research prior to the new federal system of mandatory price reporting being implemented. The market transparency issue is investigated by comparing price data collected from the former AMS voluntary price reporting system to mandatory price reporting data for live slaughter steers collected by the State of South Dakota before the advent of the new federal system. The relationship between a set of public price report series and the South Dakota mandatory price series is analyzed using cointegration techniques. The empirical findings indicate a strong long-run and short-run integrated relationship between the mandatory price series and a majority of the selected public price reports. We conclude that in the cash market for live steers in South Dakota, the former voluntary price reporting system did foster market transparency and aided in the price discovery process.Marketing,
On the designation of the patterned associations for longitudinal Bernoulli data: weight matrix versus true correlation structure?
Due to potential violation of standard constraints for the correlation for binary data, it has been argued recently that the working correlation matrix should be viewed as a weight matrix that should not be confused with the true correlation structure. We propose two arguments to support our view to the contrary for the first-order autoregressive AR(1) correlation matrix. First, we prove that the standard constraints are not unduly restrictive for the AR(1) structure that is plausible for longitudinal data; furthermore, for the logit link function the upper boundary value only depends on the regression parameter and the change in covariate values between successive measurements. In addition, for given marginal means and parameter , we provide a general proof that satisfaction of the standard constraints for consecutive marginal means will guarantee the existence of a compatible multivariate distribution with an AR(1) structure. The relative laxity of the standard constraints for the AR(1) structure coupled with the existence of a simple model that yields data with an AR(1) structure bolsters our view that for the AR(1) structure at least, it is appropriate to view this model as a correlation structure versus a weight matrix
Are SERMs safe and effective for the treatment of hypogonadism in men?
Q: Are SERMs safe and effective for the treatment of hypogonadism in men? Evidence-based answer: YES. For both normal-weight and obese men with low testosterone levels and hypogonadal symptoms, selective estrogen receptor modulators (SERMs), such as clomiphene citrate (CC) and enclomiphene citrate (EC), appear to be effective and safe for improving serum
testosterone levels (strength of recommendation [SOR]: C, disease-oriented outcomes from randomized controlled trials [RCTs] and cohort studies). Studies also show that symptom improvement is comparable to that with exogenous testosterone
replacement and similar to eugonadal men (SOR: B, patient-oriented outcomes from retrospective cohort studies).Tina Joseph, DO; Lawrence M. Gibbs, MD, MSEd, FAAFP; Kim Pham, DO (Methodist Charlton Family Medicine Residency, Dallas, TX)Includes bibliographical reference
Minimum-Cost Coverage of Point Sets by Disks
We consider a class of geometric facility location problems in which the goal
is to determine a set X of disks given by their centers (t_j) and radii (r_j)
that cover a given set of demand points Y in the plane at the smallest possible
cost. We consider cost functions of the form sum_j f(r_j), where f(r)=r^alpha
is the cost of transmission to radius r. Special cases arise for alpha=1 (sum
of radii) and alpha=2 (total area); power consumption models in wireless
network design often use an exponent alpha>2. Different scenarios arise
according to possible restrictions on the transmission centers t_j, which may
be constrained to belong to a given discrete set or to lie on a line, etc. We
obtain several new results, including (a) exact and approximation algorithms
for selecting transmission points t_j on a given line in order to cover demand
points Y in the plane; (b) approximation algorithms (and an algebraic
intractability result) for selecting an optimal line on which to place
transmission points to cover Y; (c) a proof of NP-hardness for a discrete set
of transmission points in the plane and any fixed alpha>1; and (d) a
polynomial-time approximation scheme for the problem of computing a minimum
cost covering tour (MCCT), in which the total cost is a linear combination of
the transmission cost for the set of disks and the length of a tour/path that
connects the centers of the disks.Comment: 10 pages, 4 figures, Latex, to appear in ACM Symposium on
Computational Geometry 200
Catecholaminergic connectivity to the inner ear, central auditory, and vocal motor circuitry in the plainfin midshipman fish porichthys notatus
Author Posting. Ā© John Wiley & Sons, 2014. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Journal of Comparative Neurology 522 (2014): 2887-2927, doi:10.1002/cne.23596.Although the neuroanatomical distribution of catecholaminergic
(CA) neurons has been well documented across all
vertebrate classes, few studies have examined CA connectivity
to physiologically and anatomically identified neural
circuitry that controls behavior. The goal of this study was
to characterize CA distribution in the brain and inner ear
of the plainfin midshipman fish (Porichthys notatus) with
particular emphasis on their relationship with anatomically
labeled circuitry that both produces and encodes social
acoustic signals in this species. Neurobiotin labeling of the
main auditory end organ, the saccule, combined with tyrosine
hydroxylase immunofluorescence (TH-ir) revealed a
strong CA innervation of both the peripheral and central
auditory system. Diencephalic TH-ir neurons in the periventricular
posterior tuberculum, known to be dopaminergic,
send ascending projections to the ventral telencephalon and prominent descending projections to
vocalāacoustic integration sites, notably the hindbrain
octavolateralis efferent nucleus, as well as onto the base
of hair cells in the saccule via nerve VIII. Neurobiotin backfills
of the vocal nerve in combination with TH-ir revealed
CA terminals on all components of the vocal pattern generator,
which appears to largely originate from local TH-ir
neurons but may include input from diencephalic projections
as well. This study provides strong neuroanatomical
evidence that catecholamines are important modulators of
both auditory and vocal circuitry and acoustic-driven social
behavior in midshipman fish. This demonstration of TH-ir
terminals in the main end organ of hearing in a nonmammalian
vertebrate suggests a conserved and important
anatomical and functional role for dopamine in normal
audition.National Institutes of Health; Grant number:
SC2DA034996 (to P.M.F.); Grant sponsor: The Professional Staff Congress/
The City University of New York (PSC-CUNY); Grant number:
65650-00 43 (to P.M.F.); Grant sponsor: Leonard and Claire Tow Travel
Award (to P.M.F.); Grant sponsor: Whitman Investigator Faculty Research
Fellowships from the Marine Biological Laboratory, Woods, Hole, MA
(where the study was partly conducted) (to P.M.F. and J.A.S.).2015-05-0
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Mechanisms of airfoil noise near stall conditions
The focus of this paper is on investigating the noise produced by an airfoil at high angles of attack over a range of Reynolds number
Reā2Ć10āµā4Ć10āµ. The objective is not modeling this source of noise but rather understanding the mechanisms of generation for surface pressure fluctuations, due to a separated boundary layer, that are then scattered by the trailing edge. To this aim, we use simultaneous noise and surface pressure measurement in addition to velocimetric measurements by means of hot wire anemometry and time-resolved particle image velocimetry. Three possible mechanisms for the so-called āseparation-stall noiseā have been identified in addition to a clear link between far-field noise, surface pressure, and velocity fields in the noise generation
Sigma1 Targeting to Suppress Aberrant Androgen Receptor Signaling in Prostate Cancer.
Suppression of androgen receptor (AR) activity in prostate cancer by androgen depletion or direct AR antagonist treatment, although initially effective, leads to incurable castration-resistant prostate cancer (CRPC) via compensatory mechanisms including resurgence of AR and AR splice variant (ARV) signaling. Emerging evidence suggests that Sigma1 (also known as sigma-1 receptor) is a unique chaperone or scaffolding protein that contributes to cellular protein homeostasis. We reported previously that some Sigma1-selective small molecules can be used to pharmacologically modulate protein homeostasis pathways. We hypothesized that these Sigma1-mediated responses could be exploited to suppress AR protein levels and activity. Here we demonstrate that treatment with a small-molecule Sigma1 inhibitor prevented 5Ī±- dihydrotestosterone-mediated nuclear translocation of AR and induced proteasomal degradation of AR and ARV, suppressing the transcriptional activity and protein levels of both full-length and splice-variant AR. Consistent with these data, RNAi knockdown of Sigma1 resulted in decreased AR levels and transcriptional activity. Furthermore, Sigma1 physically associated with ARV7 and A
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