A new source of X-ray line broadening: inhomogeneous strains induced by uniform homogeneous temperature conditions in polyphase or non-cubic materials

Thermal strains may contribute to X-ray diffraction line broadening in both single-phase non-cubic and in polyphase cubic polycrystalline materials even under uniform temperature conditions. A method is developed for calculating the magnitude of these thermally induced strains directly from the measured diffraction peak profiles. Corrections for particle-size effects can be made readily if particle-size broadening is significant, and the thermal diffuse scattering (TDS) contribution to the diffracted intensity can be taken into account experimentally. By this method, the strains in a Mg-5 wt% Si alloy were found to be increased by as much as 35% by a 190° C temperature change. Even in the case of this relatively low melting point alloy, the TDS effect causes only a maximum of 15% error in these measured strain effects. The interpretation of these isothermally induced strains in terms of crystal anisotropy, grain morphology and orientation and the relative sizes of phases and grains is discussed.     

Experimental observations of chemical and thermal gradients in an experimental BOF

The objective of this investigation was to determine the chemical and thermal gradients during steel making in a pilot size basic oxygen furnace. It was postulated that if these gradients could be determined under different conditions, conflicting theories of operation could be tested and optimum operating conditions would be indicated. New sample probe techniques were developed in which the probes are inserted through the side of the vessel to desired locations. Shortly after reaching the desired locations, the tip of an evacuated tube inside the probe opens and delivers metal to the other end of the probe outside the vessel. Temperatures were determined throughout the bath by specially reinforced but sensitive thermocouple probes. Important differences in both chemical and thermal gradients were found. The gradients were greatest with shallow penetration of the jet-for example after 3 min in a heat with about 1 in. penetration, the P content varied from 0.05 to 0.17 pct, silicon from 0.05 to 0.20 pct and the temperature from 2500° to 2900° F. These variations were found in a bath only 6 in. deep and 15 in. diam. By contrast, with deeper jet penetration to the center of the bath, the gradients were greatly reduced. Regardless of the operating conditions employed, the data indicate a metal circulation pattern which is upward from the jet cavity and radially outward at the surface. Even more important, by inserting a spray collector above the bath, it was found that with hard blowing the jet pumps out a volume of droplets during a heat which is equal to the bath volume. These droplets are rapidly oxidized,e.g. from 3.6 to 0.4 pct C, in their flight above the bath and are an important consideration in refining.     

Diagnosis and management of colovesical fistulas

Diagnosis and management may present difficult problems in patients with colovesical fistulas. Symptoms in the urinary tract are most common, and cystoscopy, and cystography are the most valuable diagnostic procedures. It may not always be possible to demonstrate the fistula by diagnostic tests, and a high index of suspicion should be maintained in patients with inflammatory or neoplastic disease of the rectosigmoid area or bladder with recurrent cystitis. Definitive treatment should include resection of the fistula and diseased segment of the intestine. Both one stage and multistage procedures have their place in the treatment of this condition. There are specific criteria for success for a one stage procedure.     

Integration of knowledge-based metabolic predictions with liquid chromatography data-dependent tandem mass spectrometry for drug metabolism studies: application to studies on the biotransformation of indinavir

Despite recent advances in the application of data-dependent liquid chromatography/tandem mass spectrometry (LC/MS/MS) to the identification of drug metabolites in complex biological matrixes, a prior knowledge of the likely routes of biotransformation of the therapeutic agent of interest greatly facilitates the detection and structural characterization of its metabolites. Thus, prediction of the [M + H]+ m/z values of expected metabolites allows for the construction of user-defined MS(n) protocols that frequently reveal the presence of minor drug metabolites, even in the presence of a vast excess of coeluting endogenous constituents. However, this approach suffers from inherent user bias, as a result of which additional "survey scans" (e.g., precursor ion and constant neutral loss scans) are required to ensure detection of as many drug-related components in the sample as possible. In the present study, a novel approach to this problem has been evaluated, in which knowledge-based predictions of metabolic pathways are first derived from a commercial database, the output from which is used to formulate a list-dependent LC/MS(n) data acquisition protocol. Using indinavir as a model drug, a substructure similarity search on the MDL metabolism database with a similarity index of 60% yielded 188 "hits", pointing to the possible operation of two hydrolytic, two N-dealkylation, three N-glucuronidation, one N-methylation, and several aromatic and aliphatic oxidation pathways. Integration of this information with data-dependent LC/MS(n) analysis using an ion trap mass spectrometer led to the identification of 18 metabolites of indinavir following incubation of the drug with human hepatic postmitochondrial preparations. This result was accomplished with only a single LC/MS(n) run, representing significant savings in instrument use and operator time, and afforded an accurate view of the complex in vitro metabolic profile of this drug.     

Pavlovian appetitive contingencies and approach versus withdrawal to conditioned stimuli in pigeons.

Investigated the directed skeletal movements of 21 female White Carneaux pigeons toward signals of food or no food in 3 experiments. Ss approached and pecked an illuminated key that was positively correlated with food delivery, and positioned themselves relatively far from an illuminated key that was negatively correlated with food delivery. Key illuminations alone, random presentations of key illuminations and food, and backward pairings of key illuminations and food did not produce keypecking or consistent approach-withdrawal. Therefore, directed skeletal behavior-often believed to be conditioned and maintained primarily or exclusively by operant procedures-also emerges on Pavlovian procedures. Several kinds of alternative explanations (e.g., conditioned reinforcement effects, and stimulus substitution) for these phenomena are considered, and some potential implications for operant discrimination learning are briefly explored. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Securing the Operating System: Does lesser-known mean less at risk? Is the OS an example of security though obscurity?

It is no secret that Microsoft Windows NT is the hacker’s favourite Operating System (OS). According to defacement-tracking site Attrition.org, (www.Attrition.org) Windows NT received 54.41% of all recorded OS attacks between August 1999 and April 2001. In stark contrast, some of the lesser-known Operating Systems made up for as little as 0.1% of all OS attacks. However, despite the huge difference in the quantity of attacks, companies that employ the lesser-known systems may be at greater risk…     

Comparison of data gap-filling methods for Landsat ETM+ SLC-off imagery for monitoring forest degradation in a semi-deciduous tropical forest in Mexico

A number of methods to overcome the 2003 failure of the Landsat 7 Enhanced Thematic Mapper (ETM+) scan-line corrector (SLC) are compared in this article in a forest-monitoring application in the Yucatan Peninsula, Mexico. The objective of this comparison is to determine the best approach to accomplish SLC-off image gap-filling for the particular landscape in this region, and thereby provide continuity in the Landsat data sensor archive for forest-monitoring purposes. Four methods were tested: (1) local linear histogram matching (LLHM); (2) neighbourhood similar pixel interpolator (NSPI); (3) geostatistical neighbourhood similar pixel interpolator (GNSPI); and (4) weighted linear regression (WLR). All methods generated reasonable SLC-off gap-filling data that were visually consistent and could be employed in subsequent digital image analysis. Overall accuracy, kappa coefficients (κ), and quantity and allocation disagreement indices were used to evaluate unsupervised Iterative Self-Organizing Data Analysis (ISODATA) land-cover classification maps. In addition, Pearson correlation coefficients (r) and root mean squares of the error (RMSEs) were employed for estimates agreement with fractional land cover. The best results visually (overall accuracy > 85%, κ < 9%, quantity disagreement index < 5.5%, and allocation disagreement index < 12.5%) and statistically (r > 0.84 and RMSE < 7%) were obtained from the GNSPI method. These results suggest that the GNSPI method is suitable for routine use in reconstructing the imagery stack of Landsat ETM+ SLC-off gap-filled data for use in forest-monitoring applications in this type of heterogeneous landscape.