Helicopter main-rotor speed effects: A comparison of predicted ranges of detection from the aural detection program ICHIN and the electronic detection program ARCAS

NASA LaRC personnel have conducted a strudy of the predicted acoustic detection ranges associated with reduced helicopter main rotor speeds. This was accomplished by providing identical input information to both the aural detection program ICHIN 6, (I Can Hear It Now, version 6) and the electronic acoustic detection program ARCAS (Assessment of Rotorcraft Detection by Acoustics Sensing). In this study, it was concluded that reducing the main rotor speed of the helicopter by 27 percent reduced both the predicted aural and electronic detection ranges by approximately 50 percent. Additionally, ARCAS was observed to function better with narrowband spectral input than with one-third octave band spectral inputs and the predicted electronic range of acoustic detection is greater than the predicted aural detection range

The perception of crowding

A good deal of research has recently been directed at analyzing the relationship between population density and the perception of crowding. This research was reviewed by outlining the variables that have been shown to increase (input overload, behavioral interference, and personal space violations) and decrease (activity and termination control) the perception of crowding. It was then proposed that affective variables, as well as cognitive and behavioral variables, have a significant influence on the perception of crowding. In order to test for the effects of affective and cognitive variables on the perception of crowding, a short-term high density laboratory experiment was conducted. In this experiment, individuals in all-male, all-female, or mixed-sex groups, were exposed to a positive, neutral or negative mood-inducing film. In addition, half of the participants were given perceived control over the experience, while the remainder were given no such information. It was predicted that a positive mood-inducer would decrease perception of crowding and a negative mood-inducer would increase the perception of crowding for individuals in a high density setting. The results only partially support this prediction. Positive mood decreased perception of crowding, but only for individuals in mixed-sex groups. Mood variations had no other reliable effects on the perception of crowding. It was also predicted that individuals with perceived control would report feeling less crowded than individuals without control. This prediction was supported in only the most limited conditions. Individuals in all-women groups, sitting in middle seats, and with perceived control reported feeling less crowded than did comparable individuals without perceived control. It was also predicted that mood and perceived control would interact to affect the perception of crowding. The results failed to support this prediction. A variety of theoretical and methodological explanations for these results were examined. It was concluded that mood variations, heretofore ignored in the literature, can influence the perception of crowding, especially when stemming directly from the high density experience. Conclusions about the effect of perceived control on the perception of crowding (commonly accepted in the current literature) should be re-examined before general acceptance

Helicopter far-field acoustic levels as a function of reduced main-rotor advancing blade-tip Mach number

During the design of a helicopter, the weight, engine, rotor speed, and rotor geometry are given significant attention when considering the specific operations for which the helicopter will be used. However, the noise radiated from the helicopter and its relationship to the design variables is currently not well modeled with only a limited set of full-scale field test data to study. In general, limited field data have shown that reduced main-rotor advancing blade-tip Mach numbers result in reduced far-field noise levels. The status of a recent helicopter noise research project is reviewed. It is designed to provide flight experimental data which may be used to further understand helicopter main-rotor advancing blade-tip Mach number effects on far-field acoustic levels. Preliminary results are presented relative to tests conducted with a Sikorsky S-76A helicopter operating with both the rotor speed and the flight speed as the control variable. The rotor speed was operated within the range of 107 to 90 percent NR at nominal forward speeds of 35, 100, and 155 knots

Environmental associations of cownose ray (Rhinoptera bonasus) seasonal presence along the U.S. Atlantic Coast

Identifying the mechanistic drivers of migration can be crucial in shaping conservation and management policies. The cownose ray (Rhinoptera bonasus) is a relatively poorly understood elasmobranch species that occurs along the U.S. Atlantic coast and undergoes large-scale seasonal migrations. To better understand the drivers and timing of cownose ray seasonal migration in order to inform potential management measures, we analyzed telemetry detections of 51 mature cownose rays (38 female, 13 male) tagged with acoustic transmitters in the Maryland and Virginia portions of Chesapeake Bay. Detections within their summer habitat in Chesapeake Bay and winter habitat in the vicinity of Cape Canaveral, Florida, were matched with publicly available sea surface temperature (SST) data recorded by data buoys near the areas of tag detections and with local photoperiod and day of year. These variables were used in boosted regression tree models of ray presence (all rays combined, females only, and males only) in each seasonal habitat. Models were developed for presence during the entire summer and winter season, and for the time periods of arrival and departure from both summer and winter habitats. Seasonal presence in both summer and winter habitats was associated with distinct temperature, photoperiod, and date ranges, with temperature as the most influential variable in seasonal models. In models of arrival and departure periods, southward migration (departure from Chesapeake Bay and arrival off Cape Canaveral) was strongly associated with SST for all rays and arrival in the Chesapeake Bay region after northward migration was most strongly associated with day of year. The most influential variable during the period of northward departure from Cape Canaveral differed between males (day of year) and females (SST). This suggests that mature female northward migration may be driven by temperature while male northward migration may be driven by endogenous cues. These findings provide detailed information on the timing of cownose ray arrival at, presence in, and departure from seasonal habitats and provide potential justification for including the species in cross-taxa comparative studies on migratory behavior

Stationary solutions of the one-dimensional nonlinear Schroedinger equation: I. Case of repulsive nonlinearity

All stationary solutions to the one-dimensional nonlinear Schroedinger equation under box and periodic boundary conditions are presented in analytic form. We consider the case of repulsive nonlinearity; in a companion paper we treat the attractive case. Our solutions take the form of stationary trains of dark or grey density-notch solitons. Real stationary states are in one-to-one correspondence with those of the linear Schr\"odinger equation. Complex stationary states are uniquely nonlinear, nodeless, and symmetry-breaking. Our solutions apply to many physical contexts, including the Bose-Einstein condensate and optical pulses in fibers.Comment: 11 pages, 7 figures -- revised versio

A Concept for Preoperative and Intraoperative Molecular Imaging and Detection for Assessing Extent of Disease of Solid Tumors

The authors propose a concept of “systems engineering,” the approach to assessing the extent of diseased tissue (EODT) in solid tumors. We modeled the proof of this concept based on our clinical experience with colorectal carcinoma (CRC) and gastrinoma that included short and long-term survival data of CRC patients. This concept, applicable to various solid tumors, combines resources from surgery, nuclear medicine, radiology, pathology, and oncology needed for preoperative and intraoperative assessments of a patient’s EODT. The concept begins with a patient presenting with biopsy-proven cancer. An appropriate preferential locator (PL) is a molecule that preferentially binds to a cancer-related molecular target (i.e., tumor marker) lacking in non-malignant tissue and is the essential element. Detecting the PL after an intravenous injection requires the PL labeling with an appropriate tracer radionuclide, a fluoroprobe, or both. Preoperative imaging of the tracer’s signal requires molecular imaging modalities alone or in combination with computerized tomography (CT). These include positron emission tomography (PET), PET/CT, single-photon emission computed tomography (SPECT), SPECT/CT for preoperative imaging, gamma cameras for intraoperative imaging, and gamma-detecting probes for precise localization. Similarly, fluorescent-labeled PLs require appropriate cameras and probes. This approach provides the surgeon with real-time information needed for R0 resection

Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise

The amplification of coastal hazards such as distant-source tsunamis under future relative sea-level rise (RSLR) is poorly constrained. In southern California, the Alaska-Aleutian subduction zone has been identified as an earthquake source region of particular concern for a worst-case scenario distant-source tsunami. Here, we explore how RSLR over the next century will influence future maximum nearshore tsunami heights (MNTH) at the Ports of Los Angeles and Long Beach. Earthquake and tsunami modeling combined with local probabilistic RSLR projections show the increased potential for more frequent, relatively low magnitude earthquakes to produce distant-source tsunamis that exceed historically observed MNTH. By 2100, under RSLR projections for a high-emissions representative concentration pathway (RCP8.5), the earthquake magnitude required to produce \u3e1 m MNTH falls from ~Mw9.1 (required today) to Mw8.0, a magnitude that is ~6.7 times more frequent along the Alaska-Aleutian subduction zone

Hot Carrier Transport and Photocurrent Response in Graphene

Strong electron-electron interactions in graphene are expected to result in multiple-excitation generation by the absorption of a single photon. We show that the impact of carrier multiplication on photocurrent response is enhanced by very inefficient electron cooling, resulting in an abundance of hot carriers. The hot-carrier-mediated energy transport dominates the photoresponse and manifests itself in quantum efficiencies that can exceed unity, as well as in a characteristic dependence of the photocurrent on gate voltages. The pattern of multiple photocurrent sign changes as a function of gate voltage provides a fingerprint of hot-carrier-dominated transport and carrier multiplication.Comment: 4 pgs, 2 fg

Perturbation with Intrabodies Reveals That Calpain Cleavage Is Required for Degradation of Huntingtin Exon 1

Background: Proteolytic processing of mutant huntingtin (mHtt), the protein that causes Huntington's disease (HD), is critical for mHtt toxicity and disease progression. mHtt contains several caspase and calpain cleavage sites that generate N-terminal fragments that are more toxic than full-length mHtt. Further processing is then required for the degradation of these fragments, which in turn, reduces toxicity. This unknown, secondary degradative process represents a promising therapeutic target for HD. Methodology/Principal Findings: We have used intrabodies, intracellularly expressed antibody fragments, to gain insight into the mechanism of mutant huntingtin exon 1 (mHDx-1) clearance. Happ1, an intrabody recognizing the proline-rich region of mHDx-1, reduces the level of soluble mHDx-1 by increasing clearance. While proteasome and macroautophagy inhibitors reduce turnover of mHDx-1, Happ1 is still able to reduce mHDx-1 under these conditions, indicating Happ1-accelerated mHDx-1 clearance does not rely on these processes. In contrast, a calpain inhibitor or an inhibitor of lysosomal pH block Happ1-mediated acceleration of mHDx-1 clearance. These results suggest that mHDx-1 is cleaved by calpain, likely followed by lysosomal degradation and this process regulates the turnover rate of mHDx-1. Sequence analysis identifies amino acid (AA) 15 as a potential calpain cleavage site. Calpain cleavage of recombinant mHDx-1 in vitro yields fragments of sizes corresponding to this prediction. Moreover, when the site is blocked by binding of another intrabody, V_L12.3, turnover of soluble mHDx-1 in living cells is blocked. Conclusions/Significance: These results indicate that calpain-mediated removal of the 15 N-terminal AAs is required for the degradation of mHDx-1, a finding that may have therapeutic implications