Climatological characteristics of high altitude wind shear and lapse rate layers

Indications of the climatological distribution of wind shear and temperature lapse and inversion rates as observed by rawinsonde measurements over the western United States are recorded. Frequencies of the strongest shear, lapse rates, and inversion layer strengths were observed for a 1 year period of record and were tabulated for the lower troposphere, the upper troposphere, and five altitude intervals in the lower stratosphere. Selected bivariate frequencies were also tabulated. Strong wind shears, lapse rates, and inversion are observed less frequently as altitude increases from 175 millibars to 20 millibars. On a seasonal basis the frequencies were higher in winter than in summer except for minor influences due to increased tropopause altitude in summer and the stratospheric wind reversal in the spring and fall

Markov chain techniques for predicting the maximum wind in the maximum dynamic pressure region for launching space vehicles

Markov chain techniques for predicting maximum wind in maximum dynamic pressure region for spacecraft launchin

Revised prediction (estimation) of Cape Kennedy, Florida, wind speed profile

The prediction of the wind profile maximum speed at Cape Kennedy, Florida, is made for any selected calendar data. The prediction is based on a normal probability distribution model with 15 years of smoothed input data and is static in the sense that no dynamic principles of persistence or synoptic features are considered. Comparison with similar predictions based on 6 years of data shows the same general pattern, but the variability decreased with the increase of sample size

Probabilities of good, marginal, and poor flying conditions for space shuttle ferry flights

Empirical probabilities are provided for good, marginal, and poor flying weather for ferrying the Space Shuttle Orbiter from Edwards AFB, California, to Kennedy Space Center, Florida, and from Edwards AFB to Marshall Space Flight Center, Alabama. Results are given by month for each overall route plus segments of each route. The criteria for defining a day as good, marginal, or poor and the method of computing the relative frequencies and conditional probabilities for monthly reference periods are described

An empirical analysis of the 10-15 km maximum winds to determine Apollo and AAP launch opportunities, Cape Kennedy, Florida

Empirical analysis of maximum wind speeds in space vehicular dynamic pressure region over Cape Kennedy for Apollo and AAP launche

Impulse control disorders in Parkinson's disease: decreased striatal dopamine transporter levels

Objective Impulse control disorders are commonly associated with dopaminergic therapy in Parkinson's disease (PD). PD patients with impulse control disorders demonstrate enhanced dopamine release to conditioned cues and a gambling task on [11C]raclopride positron emission tomography (PET) imaging and enhanced ventral striatal activity to reward on functional MRI. We compared PD patients with impulse control disorders and age-matched and gender-matched controls without impulse control disorders using [123I]FP-CIT (2β-carbomethoxy-3β-(4-iodophenyl)tropane) single photon emission computed tomography (SPECT), to assess striatal dopamine transporter (DAT) density. Methods The [123I]FP-CIT binding data in the striatum were compared between 15 PD patients with and 15 without impulse control disorders using independent t tests. Results Those with impulse control disorders showed significantly lower DAT binding in the right striatum with a trend in the left (right: F(1,24)=5.93, p=0.02; left: F(1,24)=3.75, p=0.07) compared to controls. Conclusions Our findings suggest that greater dopaminergic striatal activity in PD patients with impulse control disorders may be partly related to decreased uptake and clearance of dopamine from the synaptic cleft. Whether these findings are related to state or trait effects is not known. These findings dovetail with reports of lower DAT levels secondary to the effects of methamphetamine and alcohol. Although any regulation of DAT by antiparkinsonian medication appears to be modest, PD patients with impulse control disorders may be differentially sensitive to regulatory mechanisms of DAT expression by dopaminergic medications

Thermopower of Aharonov-Bohm Interferometer with a Quantum Dot

We report on the thermopower of an Aharonov-Bohm interferometer (AB) with a quantum dot in the Kondo limit. The thermopower is anomalously enhanced due to the Kondo effect as in heavy fermion systems. In contrast to the bulk systems, the sign of the thermopower can be changed by adjusting the energy level scheme or the particle-hole asymmetry of a dot with the gate voltage. Further the magnitude and even the sign of the thermopower in the AB ring can be changed at will with varying either magnetic fields or the gate voltages.Comment: 4 pages, 3 figures, accepted for publication in Physical Review Letter

Approximation Algorithms for Min-Sum k-Clustering and Balanced k-Median

We consider two closely related fundamental clustering problems in this paper. In the min-sum k-clustering one is given a metric space and has to partition the points into k clusters while minimizing the sum of pairwise distances between the points within the clusters. In the Balanced k-Median problem the instance is the same and one has to obtain a clustering into k cluster C1,..., Ck, where each cluster Ci has a center ci, while minimizing the total assignment costs for the points in the metric; here the cost of assigning a point j to a cluster Ci is equal to |Ci | times the j, cj distance in the metric. In this paper, we present an O(log n)-approximation for both these problems where n is the number of points in the metric that are to be served. This is an improvement over the O(−1 log1+ n)-approximation (for any constant > 0) obtained by Bartal, Charikar, and Raz [STOC ’01]. We also obtain a quasi-PTAS for Balanced k-Median in metrics with constant doubling dimension. As in the work of Bartal et al., our approximation for general metrics uses embeddings into tree metrics. The main technical contribution in this paper is an O(1)-approximation for Balanced k-Median in hierarchically separated trees (HSTs). Our improvement comes from a more direct dynamic programming approach that heavily exploits properties of standard HSTs. In this way, we avoid the reduction to special types of HSTs that were considered by Bartal et al., thereby avoiding an additional O(−1 log n) loss