Effects of Sweep and Thickness on the Static Longitudinal Aerodynamic Characteristics of a Series of Thin, Low-aspect-ratio, Highly Tapered Wings at Transonic Speeds : Transonic-bump Method

An investigation by the transonic-bump technique of the static longitudinal aerodynamic characteristics of a series of thin, low-aspect-ratio, highly tapered wings has been made in the Langley high-speed 7- by 10-foot tunnel. The Mach number range extended from about 0.60 to 1.18, with corresponding Reynolds numbers ranging from about 0.75 x 10(6) to 0.95 x 10(6). The angle of attack range was from -10 degrees to approximately 32 degrees.The effects on drag and lift-drag ratio of a variation in sweep angle from -14.03 degrees to 45 degrees with respect to the quarter-chord line for wings of 3-percent-chord thickness was found to be small in comparison to the effects of a variation in thickness from 2 percent chord to 4.5 percent chord for wings with 14.03 degree sweepback. For the range of variables considered, variations in plan form were considerably more important with regard to longitudinal stability characteristics than the variations in thickness. For the series of basic wings having an aspect ratio of 4, the most hearly linear pitching-moment characteristics were obtained with 26.57 degree of sweepback of the quarter-chord line. However, for the modified series of wings (obtained by clipping the tips of the original wings parallel to the plane of symmetry to give an aspect ratio of 3 and a taper ratio of 0.143), the most nearly linear pitching-moment characteristics were obtained with 36.87 degrees of sweepback. By decreasing the thickness-to-chord ratios from 0.03 to 0.02, a large increase in lift-curve slope was obtained for both the basic and modified wings. All of the wings of both series had fairly large inward shifts of the lateral center-of-pressure location (indicative of tip stalling) with increasing lift coefficient, except those wings having minimum sweepback angles

Association Between Cell Phone Restrictions and Teens\u27 Self-Reported Cell Phone Use While Driving

The purpose of this study was to describe the association between a range of cell phone restrictions and self-reported cell phone use while driving among teen drivers. Methods: U.S. high school students (N=780) from 14 states completed questionnaires, including items on cell phone use while driving. Cell phone restrictions for each state were identified using the Public Health Law Research Distracted Driving Law database and divided into five categories. Associations between cell phone restrictions and self-reported cell phone use while driving were estimated as odds ratios, adjusting for driving exposure. Results: In states with cell phone restrictions, teens were less likely to report talking or texting while driving, relative to teens in states with no restrictions. Talking and texting while driving were significantly less likely in states with texting restrictions for all drivers. All driver texting restrictions combined with teen hand-held phone restrictions were significantly associated with lower texting but not talking while driving. Conclusions: The presence of restrictions appears to be better than no restrictions with respect to self-reported teen cell phone use. Further research is needed to determine whether restrictions applying exclusively to teen drivers or restrictions for all drivers provide the greatest safety benefit

Optimization of Robustness of Complex Networks

Networks with a given degree distribution may be very resilient to one type of failure or attack but not to another. The goal of this work is to determine network design guidelines which maximize the robustness of networks to both random failure and intentional attack while keeping the cost of the network (which we take to be the average number of links per node) constant. We find optimal parameters for: (i) scale free networks having degree distributions with a single power-law regime, (ii) networks having degree distributions with two power-law regimes, and (iii) networks described by degree distributions containing two peaks. Of these various kinds of distributions we find that the optimal network design is one in which all but one of the nodes have the same degree, $k_1$ (close to the average number of links per node), and one node is of very large degree, $k_2 \sim N^{2/3}$, where $N$ is the number of nodes in the network.Comment: Accepted for publication in European Physical Journal

Time-resolved multi-mass ion imaging: femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera

The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with $(x,y)$ position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C$_2$F$_3$I photolysis are presented. The experiments utilized femtosecond UV and VUV (160.8~nm and 267~nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicates the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared

Solomon Islands: Western Province situation analysis

Aquatic agricultural systems (AAS) are places where farming and fishing in freshwater and/orscoastal ecosystems contribute significantly to household income and food security. Globally, theslivelihoods of many poor and vulnerable people are dependent on these systems. In recognitionsof the importance of AAS, the CGIAR Research Program (CRP) is undertaking a new generationsof global agricultural research programs on key issues affecting global food security and ruralsdevelopment. The overall goal of the research program is to improve the well-being of peoplesdependent on these systems. Solomon Islands is one of five priority countries in the AAS program,sled by WorldFish. In Solomon Islands, the AAS program operates in the Malaita Hub (MalaitasProvince) and the Western Hub (Western Province). This program and its scoping activities aressummarized in this report

Efficient massively parallel simulation of dynamic channel assignment schemes for wireless cellular communications

Fast, efficient parallel algorithms are presented for discrete event simulations of dynamic channel assignment schemes for wireless cellular communication networks. The driving events are call arrivals and departures, in continuous time, to cells geographically distributed across the service area. A dynamic channel assignment scheme decides which call arrivals to accept, and which channels to allocate to the accepted calls, attempting to minimize call blocking while ensuring co-channel interference is tolerably low. Specifically, the scheme ensures that the same channel is used concurrently at different cells only if the pairwise distances between those cells are sufficiently large. Much of the complexity of the system comes from ensuring this separation. The network is modeled as a system of interacting continuous time automata, each corresponding to a cell. To simulate the model, conservative methods are used; i.e., methods in which no errors occur in the course of the simulation and so no rollback or relaxation is needed. Implemented on a 16K processor MasPar MP-1, an elegant and simple technique provides speedups of about 15 times over an optimized serial simulation running on a high speed workstation. A drawback of this technique, typical of conservative methods, is that processor utilization is rather low. To overcome this, new methods were developed that exploit slackness in event dependencies over short intervals of time, thereby raising the utilization to above 50 percent and the speedup over the optimized serial code to about 120 times

Embryopathic Effects of Waterborne and Sediment-Accumulated Cadmium, Mercury and Zinc on Reproduction and Survival of Fish and Amphibian Populations in Kentucky

Fish and amphibian egg cultures were used to determine the embryopathic effects of cadmium, mercury, and zinc released from natural and metal-enriched sediments, and to develop egg culture bioassay procedures suitable for monitoring bottom sediments for hazardous contaminants. Eggs of the narrow-mouthed toad (Gastrophryne carolinensis), goldfish (Carassius auratus), and rainbow trout (Salmo gairdnei) were cultured in contaminant-free water added to natural and metal-enriched sediments. Exposure was initiated after fertilization (toad, goldfish) or at 10 days prehatching (trout) and maintained continuously through 4-10 days posthatching. Sediments were enriched with 0.1-100 ppm cadmium and mercury and 1.0-1000 ppm zinc. Natural control sediments contained average concentrations of 0.052 ppm mercury, 1.0 ppm cadmium, and 108.2 ppm zinc. Substantial frequencies of mortality and teratogenesis occurred for all 3 animal species when eggs were cultured over natural elements further enriched with as little as 0.1-1.0 ppm cadmium or mercury and 1-10ppm zinc. Survival of trout embryos and alevins closely paralleled sediment test concentrations. The sediment TL50 concentrations for trout stages cultured from 10 days prehatching through 10 days posthatching were approximately 1ppm for mercury, 2.15 ppm for cadmium, and 210.6 ppm for zinc. Sediment metals were substantially more lethal to eggs and embryos than to free-living larvae or fry

Note and Comment

Declaratory Judgments - The widespread interest in this ntw form of remedial instrument, which was. somewhat dashed by the recent decision of the Michigan Supreme. Court \u27n Amwmy v. Grand Ropds.Ry. Co. (r920), 211 Mich. 59, holding declaritoty relief to b! non-judicial and -outside the constitutional power of \u27courts (9ig MicH. LAw Rzv. 86), has been revived by the action of\u27the legislature of. Kansas in enacting a derlaratory judgment statute almost identical with the .Michigan act.. This was done with full knowledge of the decision in the .4mmy case, and inasmuch -as it is well known that some of the judges oti\u27the Supreme Court of Kansas have taken an active interest in advocating this reform, it is fair to assume that the act is likely tQ escape the constitutionalguillotine The English judges. have for two geneiations or m9re been the.chief proponents of English procedural. reform, and nothing *ould be more universally welcomed in this country than the generous participation and leadership of our high. judges in the efforts of\u27the public to. make\u27the administration of justice .more respoksive to social needs