The procurement and evaluation of a prototype laser satellite-tracking system Final report, 1 Jan. 1967 - 30 Sep. 1968

Pulsed ruby laser satellite tracking syste

A distributed model predictive control scheme with robustness against noncompliant controllers

A tube-based distributed model predictive control (DMPC) scheme is proposed for dynamically coupled linear systems. The control scheme is designed to guarantee local performance even when neighboring controllers are not complying with the requirements of the algorithm (e.g., they are malicious or faulty). The resulting conservativeness is minimized, for controllers aim to minimize their state and input constraint sets to reduce mutual disturbances. Also, sufficient conditions for feasibility and exponential stability are given. Finally, these ideas are illustrated and assessed with respect to other robust DMPC via a simulated example

Photographic measurements of the energy distribution in the beam of a ruby laser

Photographic measurement of energy distribution in beam of Q-switched ruby lase

Measurements of satellite range with a ruby laser

Range measurements of GEOS-I and BE-C satellites with ruby lase

Use of a laser for satellite-range measurement

Optical laser satellite range measuring syste

Investigating how queer people of color use ICTs to cope with stigma

Stigma is an attribute that differentiates and negatively classifies an individual within a specific categorized identity. Multiple identities are stigmatized, such as the LGBTQ and PoC communities. When these identities are layered on top of one another, so are the stigmas associated with them, and this creates an increased risk of negative consequences. Literature indicates that a way to ameliorate these negative consequences is to find ways to cope. This lit- erature review analyzes the current research regarding what is known about how QPOC leverage ICTs as a tool for coping with stigma. Overall, it was found that not much is known about the particular ICTs QPoC are leveraging to cope, nor is there much knowledge on how they are using these unidentified ICTs. Further research is necessary to better understand what ICTs are being used and how QPoC are using them in order to help ameliorate the negative consequences of stigma

On the relation between virial coefficients and the close-packing of hard disks and hard spheres

The question of whether the known virial coefficients are enough to determine the packing fraction $\eta_\infty$ at which the fluid equation of state of a hard-sphere fluid diverges is addressed. It is found that the information derived from the direct Pad\'e approximants to the compressibility factor constructed with the virial coefficients is inconclusive. An alternative approach is proposed which makes use of the same virial coefficients and of the equation of state in a form where the packing fraction is explicitly given as a function of the pressure. The results of this approach both for hard-disk and hard-sphere fluids, which can straightforwardly accommodate higher virial coefficients when available, lends support to the conjecture that $\eta_\infty$ is equal to the maximum packing fraction corresponding to an ordered crystalline structure.Comment: 10 pages, 6 figures; v2: discussion about hard-square and hard-hexagon systems on a lattice added; five new reference

Risk of Dementia Associated with Elevated Plasma Homocysteine in a Latin American Population

The relationship between total homocysteine (tHcy) and dementia risk remains controversial, as the association varies among populations and dementia subtypes. We studied a Venezuelan population that has high prevalence of both elevated tHcy and dementia. We tested the hypotheses that (1) elevated tHcy is associated with increased dementia risk, (2) the risk is greater for vascular dementia (VaD) than for Alzheimer's disease (AD), and (3) a history of stroke may partly explain this association. 2100 participants (≥55 years old) of the Maracaibo Aging Study underwent standardized neurological, neuropsychiatric, and cardiovascular assessments. Elevated tHcy was significantly associated with dementia, primarily VaD. When history of stroke and other confounding factors were taken into account, elevated tHcy remained a significant risk factor in older (>66 years), but not in younger (55–66 years) subjects. Ongoing studies of this population may provide insight into the mechanism by which tHcy increases risk for dementia

The apolipoprotein ϵ4 allele in Parkinson\u27s disease with and without dementia

The ϵ4 isoform of apolipoprotein E (Apo-E) may confer genetic susceptibility for familial and sporadic Alzheimer\u27s disease (AD). Because dementia in AD and Parkinson\u27s disease (PD) share many biologic and clinical features, we determined the Apo-E genotypes for 79 patients with PD, 22 of whom were demented, and for 44 age-matched healthy elderly controls from the same community. We hypothesized that if the dementia was similar to AD, there would be a higher allele frequency of apolipoprotein ϵ4 (Apoϵ4) in demented PD patients compared with nondemented PD patients and controls. The ϵ4 allele frequency for PD without dementia was 0.132, for PD with dementia, 0.068, and for controls, 0.102. There was no association between Apoϵ4 and dementia in the PD patients. We conclude that the biologic basis for dementia in PD may differ from that of AD