Multiple-mask chemical etching

Multiple masking techniques use lateral etching to reduce the total area of the high etch-rate oxide exposed to the chemical etchant. One method uses a short-term etch to remove the top layer from the silicon oxide surface, another acts before the top layer is grown

Propellant material compatibility program and results

The effects of long-term (up to 10 years) contact of inert materials with earth-storable propellants were studied for the purpose of designing chemical propulsion system components that can be used for current as well as future planetary spacecraft. The primary experimental work, and results to date are reported. Investigations include the following propellants: hydrazine, hydrazine-hydrazine nitrate blends, monomethyl-hydrazine, and nitrogen tetroxide. Materials include: aluminum alloys, corrosion-resistant steels, and titanium alloys. More than 700 test specimen capsules were placed in long-term storage testing at 43 C in the special material compatibility facility. Material ratings relative to the 10-year requirement have been assigned

Hydrogen bonding in substituted nitroanilines : isolated nets in 1,3-diamino-4-nitrobenzene and continuously interwoven nets in 3,5-dinitroaniline

Peer reviewedPublisher PD

Invariant Peano curves of expanding Thurston maps

We consider Thurston maps, i.e., branched covering maps $f\colon S^2\to S^2$ that are postcritically finite. In addition, we assume that $f$ is expanding in a suitable sense. It is shown that each sufficiently high iterate $F=f^n$ of $f$ is semi-conjugate to $z^d\colon S^1\to S^1$, where $d$ is equal to the degree of $F$. More precisely, for such an $F$ we construct a Peano curve $\gamma\colon S^1\to S^2$ (onto), such that $F\circ \gamma(z) = \gamma(z^d)$ (for all $z\in S^1$).Comment: 63 pages, 12 figure

Connectivity-enhanced diffusion analysis reveals white matter density disruptions in first episode and chronic schizophrenia.

Reduced fractional anisotropy (FA) is a well-established correlate of schizophrenia, but it remains unclear whether these tensor-based differences are the result of axon damage and/or organizational changes and whether the changes are progressive in the adult course of illness. Diffusion MRI data were collected in 81 schizophrenia patients (54 first episode and 27 chronic) and 64 controls. Analysis of FA was combined with "fixel-based" analysis, the latter of which leverages connectivity and crossing-fiber information to assess both fiber bundle density and organizational complexity (i.e., presence and magnitude of off-axis diffusion signal). Compared with controls, patients with schizophrenia displayed clusters of significantly lower FA in the bilateral frontal lobes, right dorsal centrum semiovale, and the left anterior limb of the internal capsule. All FA-based group differences overlapped substantially with regions containing complex fiber architecture. FA within these clusters was positively correlated with principal axis fiber density, but inversely correlated with both secondary/tertiary axis fiber density and voxel-wise fiber complexity. Crossing fiber complexity had the strongest (inverse) association with FA (r = -0.82). When crossing fiber structure was modeled in the MRtrix fixel-based analysis pipeline, patients exhibited significantly lower fiber density compared to controls in the dorsal and posterior corpus callosum (central, postcentral, and forceps major). Findings of lower FA in patients with schizophrenia likely reflect two inversely related signals: reduced density of principal axis fiber tracts and increased off-axis diffusion sources. Whereas the former confirms at least some regions where myelin and or/axon count are lower in schizophrenia, the latter indicates that the FA signal from principal axis fiber coherence is broadly contaminated by macrostructural complexity, and therefore does not necessarily reflect microstructural group differences. These results underline the need to move beyond tensor-based models in favor of acquisition and analysis techniques that can help disambiguate different sources of white matter disruptions associated with schizophrenia

If Hay Mows Are Empty

Dairy cows fed plenty of silage, properly balanced with a grain mixture, will produce just as well and keep in as good condition as those fed both alfalfa hay and silage as roughage. In other words, apparently cows do not need a dry roughage along with silage

Normal growth in dairy cattle

Male calves of all the breeds studied weighed more at birth than female calves. The birth weights of female calves were as follows: Holsteins, 89 pounds; Guernseys, 65 pounds; Ayrshires, 63 pounds; and Jerseys, 50 pounds. There was considerable variation among individuals in their live weights. Coefficients of variation ranged from above 15 percent in calves to less than 10 percent in 2-year old heifers. The data show that the time of first freshening marks the greatest change in the rate of growth in live weight. Very little difference can be observed in the relative rates at which animals of the different breeds approach mature size. Mature growth values are approached most rapidly in height at withers. This measurement is not even doubled from birth to maturity. Holsteins, Ayrshires and Jerseys are wider in relation to depth than Guernseys. The average weight for mature Holsteins in the Iowa Experiment Station herd may be considered as 1,405 pounds; Ayrshires, 1,111 pounds; Guernseys, 1,072 pounds; and Jerseys, 950 pounds. Gestation and lactation are shown to have considerable influence upon live weight. Late freshening heifers weigh more than heifers calving at the usual time but after freshening the weights of both groups are quite comparable

Efficiency of dairy rations containing various quantities of grain

The dairy cow is particularly well adapted for consuming and utilizing large quantities of roughages, though she responds well to grain feeding. The relative quantities of roughage and grain that should be fed are usually determined by the physiologic effects and economic efficiencies of such rations when fed to dairy cattle. One would hardly expect high.producing cows to maintain a high yield when consuming roughage alone, because such a ration is so bulky that it prevents the intake of sufficient nutrients for maximum production. And yet, very good results have been obtained in certain areas by such a system of feeding. Then, too, the nutrients of roughage crops are usually produced at considerably less cost than those of grain crops (17) (3). Furthermore, rough. ages are more plentiful on most farms than grain crops, especially in recent years when there has been a marked increase in the production of hay and pasture crops at some sacrifice of grain production. Under these conditions the advisability of supplementing roughage rations with grain becomes a question of interest to dairy farmers

Cows Are Good Bean Market

Dairy cows will produce more butterfat on a ration in which whole (cracked) soybeans provide the protein supplement than on an ordinary ration of mixed grains which uses such a protein supplement as soybean oilmeal