184 research outputs found
Calcospherite (Calcification Nodule) Size in the Short Rib Polydactyly Syndromes
The short rib polydactyly syndromes (SRP) are lethal neonatal skeletal dysplasias with a narrow chest, short limbs, and other abnormalities. Type II (Majewski) short rib polydactyly can be distinguished from the Type I/III (Saldino-Noonan) type on the basis of radiographic and histologic changes. Our previous transmission electron microscopic studies suggested unusual patterns of cartilage calcification in these syndromes. We evaluate calcification in the present study using scanning electron microscopy and quantitative morphometry of calcification regions digested to expose calcospherite nodules (calcification nodules), distinctive morphologic structures which form during cartilage calcification. Mean calcospherite area of the Majewski Type II SRP (3.5 ± 0.24 x 10-6 mm2 (3) (mean ± sem (n)) did not differ from normal control means (3.1 ± 0.5 x 10-6 mm2, (3)). The mean area for Type I/III, however, was significantly larger than both the control and Type II means (8.9 ± 1.16 x 10-6 mm2 (7), p=.001). This difference in calcospherite size adds a further differentiating feature between these two dysplasias
Brittle-to-ductile transition in ultrathin Ta/Cu film systems
Current semiconductor technology demands the use of compliant substrates for flexible integrated circuits. However, the maximum total strain of such devices is often limited by the extensibility of the metallic components. Although cracking in thin films is extensively studied theoretically, little experimental work has been carried out thus far. Here, we present a systematic study of the cracking behavior of 34- to 506-nm-thick Cu films on polyamide with 3.5-to 19-nm-thick Ta interlayers. The film systems have been investigated by a synchrotron-based tensile testing technique and in situ tensile tests in a scanning electron microscope. By relating the energy release during cracking obtained from the stress-strain curves to the crack area, the fracture toughness of the Cu films can be obtained. It increases with Cu film thickness and decreases with increasing Ta film thickness. Films thinner than 70 nm exhibit brittle fracture, indicating an increasing inherent brittleness of the Cu film
Temperature dependence of mechanical properties in ultrathin Au films with and without passivation
Temperature and film thickness are expected to have an influence on the mechanical properties of thin films. However, mechanical testing of ultrathin metallic films at elevated temperatures is difficult, and few experiments have been conducted to date. Here, we present a systematic study of the mechanical properties of 80-500-nm-thick polycrystalline Au films with and without SiNx passivation layers in the temperature range from 123 to 473 K. The films were tested by a novel synchrotron-based tensile testing technique. Pure Au films showed strong temperature dependence above 373 K, which may be explained by diffusional creep. In contrast, passivated samples appeared to deform by thermally activated dislocation glide. The observed activation energies for both mechanisms are considerably lower than those for the bulk material, indicating that concomitant stress relaxation mechanisms are more pronounced in the thin film geometr
Temperature dependence of mechanical properties in ultrathin Au films with and without passivation
Requirement for DNA Ligase IV during Embryonic Neuronal Development
The embryonic ventricular and subventricular zones (VZ/SVZ) contain the neuronal stem and progenitor cells and undergo rapid proliferation. The intermediate zone (IZ) contains nonreplicating, differentiated cells. The VZ/SVZ is hypersensitive to radiation-induced apoptosis. Ablation of DNA non-homologous end-joining (NHEJ) proteins, XRCC4 or DNA ligase IV (LigIV), confers ataxia telangiectasia mutated (ATM)-dependent apoptosis predominantly in the IZ. We examine the mechanistic basis underlying these distinct sensitivities using a viable LigIV (Lig4(Y288C)) mouse, which permits an examination of the DNA damage responses in the embryonic and adult brain. Via combined analysis of DNA breakage, apoptosis, and cell-cycle checkpoint control in tissues, we show that apoptosis in the VZ/SVZ and IZ is activated by low numbers of DNA double-strand breaks (DSBs). Unexpectedly, high sensitivity in the VZ/SVZ arises from sensitive activation of ATM-dependent apoptosis plus an ATM-independent process. In contrast, the IZ appears to be hypersensitive to persistent DSBs. NHEJ functions efficiently in both compartments. The VZ/SVZ and IZ regions incur high endogenous DNA breakage, which correlates with VZ proliferation. We demonstrate a functional G(2)/M checkpoint in VZ/SVZ cells and show that it is not activated by low numbers of DSBs, allowing damaged VZ/SVZ cells to transit into the IZ. We propose a novel model in which microcephaly in LIG4 syndrome arises from sensitive apoptotic induction from persisting DSBs in the IZ, which arise from high endogenous breakage in the VZ/SVZ and transit of damaged cells to the IZ. The VZ/SVZ, in contrast, is highly sensitive to acute radiation-induced DSB formation
Tape Placement Head for Applying Thermoplastic Tape to an Object
A tape placement head for applying thermoplastic tape to an object includes a heated feeder which guides the tape/tow to a heated zone. The heated zone has a line compactor having a single row of at least one movable heated member. An area compactor is located in the heated zone downstream from the line compactor. The area compactor includes a plurality of rows of movable feet which are extendable toward the tape/tow different distances with respect to each other to conform to the shape of the object. A shim is located between the heated compactors and the tape/tow. A chilled compactor is in a chilled zone downstream from the heated zone. The chilled zone includes a line chilled compactor and an area chilled compactor. A chilled shim is mounted between the chilled compactor and the tape/tow
Atmospheric potential oxygen: New observations and their implications for some atmospheric and oceanic models
Measurements of atmospheric O2/N2 ratios and CO2 concentrations can be combined into a tracer known as atmospheric potential oxygen (APO ≈ O2/N2 + CO2) that is conservative with respect to terrestrial biological activity. Consequently, APO reflects primarily ocean biogeochemistry and atmospheric circulation. Building on the work of Stephens et al. (1998), we present a set of APO observations for the years 1996-2003 with unprecedented spatial coverage. Combining data from the Princeton and Scripps air sampling programs, the data set includes new observations collected from ships in the low-latitude Pacific. The data show a smaller interhemispheric APO gradient than was observed in past studies, and different structure within the hemispheres. These differences appear to be due primarily to real changes in the APO field over time. The data also show a significant maximum in APO near the equator. Following the approach of Gruber et al. (2001), we compare these observations with predictions of APO generated from ocean O2 and CO2 flux fields and forward models of atmospheric transport. Our model predictions differ from those of earlier modeling studies, reflecting primarily the choice of atmospheric transport model (TM3 in this study). The model predictions show generally good agreement with the observations, matching the size of the interhemispheric gradient, the approximate amplitude and extent of the equatorial maximum, and the amplitude and phasing of the seasonal APO cycle at most stations. Room for improvement remains. The agreement in the interhemispheric gradient appears to be coincidental; over the last decade, the true APO gradient has evolved to a value that is consistent with our time-independent model. In addition, the equatorial maximum is somewhat more pronounced in the data than the model. This may be due to overly vigorous model transport, or insufficient spatial resolution in the air-sea fluxes used in our modeling effort. Finally, the seasonal cycles predicted by the model of atmospheric transport show evidence of an excessive seasonal rectifier in the Aleutian Islands and smaller problems elsewhere. Copyright 2006 by the American Geophysical Union
New body scales reveal body dissatisfaction, thin-ideal, and muscularity-ideal in males
The aim of the current study was to develop, test, and re-test two new male body dissatisfaction scales: The Male Body Scale (MBS; consisting of emaciated to obese figures) and the Male Fit Body Scale (MFBS; consisting of emaciated to muscular figures). These scales were compared to the two most commonly used visually-based indices of body dissatisfaction (Stunkard Figure Rating Scale, SFRS; and Somatomorphic Matrix, SM). Male participants rated which body figure on each scale most represented their current figure, then their ideal figure, and then rated which one of the three scales (MBS, MFBS, and SFRS) best represented their current and ideal body overall. Finally, they completed the Drive for Muscularity Scale (DMS), the Eating Disorder Examination Questionnaire (EDE-Q 6.0), and their actual body composition was calculated. This was followed by a re-test and manipulation check two to six weeks later. Participants’ actual body mass index, fat- and muscularity-percentage were all highly related to their current body figure choice, and both new scales were consistently valid and more reliable between test and re-test than the SFRS and SM body dissatisfaction scores. Importantly, each scale was sensitive to different types of body dissatisfaction within males. Specifically, the MBS revealed that males’ desire for the thin-ideal significantly corresponded to higher eating disorder tendencies as identified by EDE-Q 6.0 scores, whilst the MFBS revealed much higher body dissatisfaction toward the larger, muscularity-ideal, predicting higher drive for muscularity as identified by DMS scores. Results validated the new scales, and inform male-focused eating disorder research
The Version-2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979–Present)
The Global Precipitation Climatology Project (GPCP) Version-2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.58 latitude 3 2.58 longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit satellite infrared data, and surface rain gauge obser-vations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The dataset is extended back into the prem-icrowave era (before mid-1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the rain gauge analysis. The dataset archive also contains the individual input fields, a combined satellite estimate, and error estimates for each field. This monthly analysis is the foundation for the GPCP suite of products, including those at finer temporal resolution. The 23-yr GPCP climatology is characterized, along with time and space variations of precipitation. 1
Circulation of the North Atlantic Ocean from altimetry and the Gravity Recovery and Climate Experiment geoid
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C03005, doi:10.1029/2005JC003128.We discuss the ocean circulation derived from the temporally averaged sea surface height, which is referenced to the recently released geoid from the Gravity Recovery and Climate Experiment (GRACE) mission (GRACE Gravity Model 02 (GGM02)). The creation of a precise, independent geoid allows for the calculation of the reference gravitational potential undulation surface, which is associated with the resting ocean surface height. This reference height is then removed from the temporally averaged sea surface height, leaving the dynamic ocean topography. At its most basic level the dynamic ocean topography can be related to the ocean's surface circulation through geostrophy. This has previously been impracticable because of large uncertainties in previous estimates of the Earth's geoid. Prior geoids included the temporally averaged sea surface from altimeters as a proxy for the geoid and therefore were unsuitable for calculations of the ocean's circulation. Geoid undulations are calculated from the GRACE geoid and compared to those from the NASA Goddard Space Flight Center and National Imagery and Mapping Agency Joint Earth Geopotential Model (EGM96) geoid. Error estimates are made to assess the accuracy of the new geoid. The deep ocean pressure field is also estimated by combining the calculated dynamic ocean topography with hydrography. Finally, the derived circulation is compared to independent observations of the circulation from sea surface drifters and subsurface floats. It is shown that the GGM02 geoid is significantly more accurate for use in estimating the ocean's circulation.This work was supported by grants
NNG04GE95G from the National Aeronautics and Space Administration
and OCE 01-37122 from the National Science Foundation and the Young
Investigator Program award N00014-03-1-0545 from the Office of Naval
Research
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