Lead telluride bonding and segmentation study Semiannual phase report, 1 Feb. - 31 Jul. 1969

Thermoelectric system of Cd-Si-Ge, and tungsten diffusion bonded lead tellurid

Dopaminergic Regulation of Circadian Food Anticipatory Activity Rhythms in the Rat

Circadian activity rhythms are jointly controlled by a master pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) and by food-entrainable circadian oscillators (FEOs) located elsewhere. The SCN mediates synchrony to daily light-dark cycles, whereas FEOs generate activity rhythms synchronized with regular daily mealtimes. The location of FEOs generating food anticipation rhythms, and the pathways that entrain these FEOs, remain to be clarified. To gain insight into entrainment pathways, we developed a protocol for measuring phase shifts of anticipatory activity rhythms in response to pharmacological probes. We used this protocol to examine a role for dopamine signaling in the timing of circadian food anticipation. To generate a stable food anticipation rhythm, rats were fed 3h/day beginning 6-h after lights-on or in constant light for at least 3 weeks. Rats then received the D2 agonist quinpirole (1 mg/kg IP) alone or after pretreatment with the dopamine synthesis inhibitor α-methylparatyrosine (AMPT). By comparison with vehicle injections, quinpirole administered 1-h before lights-off (19h before mealtime) induced a phase delay of activity onset prior to the next meal. Delay shifts were larger in rats pretreated with AMPT, and smaller following quinpirole administered 4-h after lights-on. A significant shift was not observed in response to the D1 agonist SKF81297. These results provide evidence that signaling at D2 receptors is involved in phase control of FEOs responsible for circadian food anticipatory rhythms in rats

Midday Meals Do Not Impair Mouse Memory

Nocturnal mice fed in the middle of the light period exhibit food anticipatory rhythms of behavior and physiology under control of food-entrainable circadian clocks in the brain and body. This is presumed to be adaptive by aligning behavior and physiology with predictable mealtimes. This assumption is challenged by a report that daytime feeding schedules impair cognitive processes important for survival, including object memory and contextual fear conditioning assessed at two times of day. To further evaluate these effects, mice were restricted to a 6 h daily meal in the middle of the light or dark period and object memory was tested at four times of day. Object memory was not impaired by daytime feeding, and did not exhibit circadian variation in either group. To determine whether impairment might depend on methodology, experimental procedures used previously to detect impairment were followed. Daytime feeding induced food anticipatory rhythms and shifted hippocampal clock genes, but again did not impair object memory. Spontaneous alternation and contextual fear conditioning were also not impaired. Hippocampal memory function appears more robust to time of day and daytime feeding schedules than previously reported; day-fed mice can remember what they have seen, where they have been, and where it is dangerous

Cardiovascular Disease and Type 2 Diabetes in Evolutionary Perspective: A Critical Role for Helminths?

Heart disease and type 2 diabetes are commonly believed to be rare among contemporary subsistencelevel human populations, and by extension prehistoric populations. Although some caveats remain, evidence shows these diseases to be unusual among well-studied hunter-gatherers and other subsistence populations with minimal access to healthcare. Here we expand on a relatively new proposal for why these and other populations may not show major signs of these diseases. Chronic infections, especially helminths, may offer protection against heart disease and diabetes through direct and indirect pathways. As part of a strategy to insure their own survival and reproduction, helminths exert multiple cardio-protective effects on their host through their effects on immune function and blood lipid metabolism. Helminths consume blood lipids and glucose, alter lipid metabolism, and modulate immune function towards Th-2 polarization—which combined can lower blood cholesterol, reduce obesity, increase insulin sensitivity, decrease atheroma progression, and reduce likelihood of atherosclerotic plaque rupture. Traditional cardiometabolic risk factors, coupled with the mismatch between our evolved immune systems and modern, hygienic environments may interact in complex ways. In this review, we survey existing studies in the non-human animal and human literature, highlight unresolved questions and suggest future directions to explore the role of helminths in the etiology of cardio-metabolic disease

The Spectral Properties of Pitted Impact Deposits on Vesta as Seen by the Dawn VIR Instrument

Pitted impact deposits (PIDs) on Vesta have been shown to exhibit distinct spectral characteristics with respect to their surrounding host deposits and other typical Vestan areas regarding the first major pyroxene absorption near 0.9 μm. The PIDs, especially those in the ejecta blanket of the large crater Marcia, show higher reflectance and pyroxene band strength with respect to their impact deposit surroundings. This study complements the spectral characterization of the PIDs on Vesta with Visible and Infrared Spectrometer observations obtained by NASA’s Dawn mission. In particular, we focus on the second major pyroxene absorption near 1.9 μm. We analyze nine PIDs in the ejecta blanket of the crater Marcia, as well as PIDs within the crater-fill deposits of the craters Marcia, Cornelia, and Licinia. We find that the second pyroxene absorption behaves in similar ways as the first major pyroxene absorption. The PIDs in Marcia’s ejecta blanket show higher reflectance and pyroxene band strength with respect to their immediate impact deposit surroundings. The PIDs present in the crater-fill deposits of Marcia, Cornelia, and Licinia, however, do not show such spectral characteristics. This is also consistent with previous observations of the first pyroxene absorption band. Based on the experimental results of other studies, we speculate that the observed spectral distinctness arises from an oxidation process in the interior of impact deposits, where Fe cations migrate within their host pyroxene grains. Thus, the surfaces of (melt-bearing) impact deposits might be different from their interiors, apart from space-weathering effects

2-[2-Benzoyl-3,3-bis­(methyl­sulfan­yl)prop-2-enyl­idene]malononitrile

The title compound, C15H12N2OS2, is an example of a push–pull butadiene in which the electron-releasing methyl­sulfanyl groups and electron-withdrawing nitrile groups on either end of the butadiene chain enhance the conjugation in the system. Short intra­molecular C—H⋯S inter­actions are observed. In the crystal structure, an O⋯C short contact of 2.917 (3) Å is observed

Laboratory VIS–NIR reflectance measurements of heated Vesta regolith analogs: Unraveling the spectral properties of the pitted impact deposits on Vesta

Pitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes