Daguerreotype Portraiture

Abstract

Facing the Light is a major national exhibition of 110 daguerreotype portraits gathered from 35 sources. In his introduction to this catalogue for the exhibition, Pfister outlines his criteria for selection in the National Portrait Gallery's show. For consideration, the works had to be ‘unmistakably identified portraits of nationally prominent individuals … [whose] inclusion was first determined by the existence of a striking example of the daguerrean [sic] art’. This respect for the medium, as well as for the likenesses represented, makes the book a happy blend that should appeal to a broad audience. It is fitting that a national exhibition sponsored in part by the government and in part by the public-minded Polaroid Corporation should have set itself this task.     

Accuracy assessment of the MODIS 16-day albedo product for snow: comparisons with Greenland in situ measurements

The accuracy of the Moderate Resolution Imaging Spectroradiometer (MODIS) 16-day albedo product (MOD43) is assessed using ground-based albedo observations from automatic weather stations (AWS) over spatially homogeneous snow and semihomogeneous ice-covered surfaces on the Greenland ice sheet. Data from 16 AWS locations, spanning the years 2000-2003, were used for this assessment. In situ reflected shortwave data were corrected for a systematic positive spectral sensitivity bias of between 0.01 and 0.09 on a site-by-site basis using precise optical black radiometer data. Results indicate that the MOD43 albedo product retrieves snow albedo with an average root mean square error (RMSE) of ±0.07 as compared to the station measurements, which have ±0.035 RMSE uncertainty. If we eliminate all satellite retrievals that rely on the backup algorithm and consider only the highest quality results from the primary bidirectional reflectance distribution function (BRDF) algorithm, the MODIS albedo RMSE is ±0.04, slightly larger than the in situ measurement uncertainty. There is general agreement between MODIS and in situ observations for albedo <0.7, while near the upper limit, a −0.05 MODIS albedo bias is evident from the scatter of the 16-site composite.     

Validation of the MODIS bidirectional reflectance distribution function and albedo retrievals using combined observations from the aqua and terra platforms

We evaluate the performance of the MODerate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF)/Albedo algorithm using observations from MODIS instruments aboard NASA's Terra (EOS AM-1) and Aqua (EOS PM-1) platforms. This "combined" albedo product is evaluated against continuous field measurements from SURFace RADiation Budget Network (SURFRAD) and Atmospheric Radiation Measurement Southern Great Plains (ARM/SGP) stations, and through an internal analysis of the product's quality assurance (QA) fields. The combined product is compared to the initial MODIS albedo product, which used observations from the Terra satellite only. During the spring and summer months, the combined product showed a slight improvement over the original Terra-only albedo product, with a root mean square error (RMSE) of 0.0130 and a bias of about -0.02. As with the Terra-only product, accuracy drops during the fall and winter months at some sites. Jin et al. found that increased heterogeneity of validation sites during the fall and winter months is partially responsible for this drop in accuracy. The additional data provided by the Aqua platform changes high-quality albedo estimations only slightly, which underscores the stability of the MODIS algorithm. The most significant benefit of the combined product is a near 50% decrease in lower quality backup algorithm retrievals for the entire globe. A decrease in backup algorithm retrievals improves the overall accuracy of the MODIS albedo product, as it reduces algorithm reliance upon an a priori determination of the underlying surface anisotropy that is not entirely data derived.     

Einfluß von Sauerstoffzusätzen beim Gasnitrieren auf den strukturellen Aufbau von Nitrierschichten

Influence of oxygen additions during gas nitriding on the structure of the nitrided layers The influence of controlled oxygen additions during gas nitriding of steels on the structure and built-up of the nitrided layers as well as on the nitriding reactions was investigated with metallurgical methods and Mössbauer spectroscopy. The results show that oxygen additions below the oxidising threshold slightly improve the nitriding behaviour of unalloyed steels. Furthermore, it is shown that for alloyed steel, which are tending to passivation starting form chromium concentrations of 3%, the nitriding can be considerably improved by oxygen additions. The passivation layers present for these steels are destroyed by external oxidation during the oxinitriding process. This external oxidation and the internal nitriding occurred parallel in the early stages of the oxinitriding.     

Accident versus near miss causation: a critical review of the literature, an empirical test in the UK railway domain, and their implications for other sectors

An essential assumption for the usefulness of basing accident prevention measures on minor incidents is the common cause hypothesis: that causal pathways of near misses are similar to those of actual accidents (such as injuries and damages). The idea of a common cause hypothesis was originally proposed by Heinrich in his seminal book "Industrial Accident Prevention" [McGraw-Hill, New York]. In this paper, it is argued that the hypothesis of similarity of causes for major and minor accidents has become confounded with the interdependence of the ratio relationship between severity and frequency. This confounded view of the hypothesis has led to invalid tests of the hypothesis and erroneous conclusions. The evidence from various studies is examined and it is concluded that the hypothesis has not been properly understood or tested. Consequently, such a proper test was carried out using data from the UK railways which were analysed using the confidential incident reporting and analysis system (CIRAS) 21 cause taxonomy. The results provide qualified support for the common cause hypothesis with only three out of the 21 types of causes having significantly different proportions for the three consequence levels investigated: 'injury & fatality', 'damage' and 'near miss'.     

Nanoindentation of nano-Al/Si3N4 multilayers with Vickers and Brinell indenters

The mechanical properties of ceramics films at the sub-micron, even nanometer length scale have attracted increased attention due to the high-speed development of microelectronic technology. In this work, nano-indentation hardness as a function of the different individual layer thickness has been measured and investigated in the sputtered Al/Si₃N₄ multilayers with different indenters (Vickers and Brinell). For this ceramics/metal multilayers system, the hardness of the multilayers increases with decreasing individual layer thickness from 500 nm to 100 nm and from 50 nm to 10 nm, indicating a significant size effect. At the same time, changes in the deformation behavior may be controlled by different deformation mechanisms for submicron scale and nanometer scale.     

Mayall's life-size portrait of George Peabody

Abstract

The miniature painter's occupation is nearly gone, and we may perhaps see the second-rate portrait painter also superseded, and the same negative made to print pictures for the walls of town-hall or mansion, or for the album in the lady's boudoir.     

Insulin-like growth factor system in serum and cerebrospinal fluid in patients with multiple sclerosis

Perforation during attempted gas-enema reduction of intussusception is more common than during a barium enema. In a review of 650 consecutive attempted gas enemas, perforation occurred in 7 infants (1.1%). Gross abdominal distension from the pneumoperitoneum may be rapid and cause splinting of the diaphragm, which leads to acute respiratory distress. This complication is readily recognised at the time of the gas enema, and may require immediate intervention by paracentesis using a 14-gauge needle. A review of 7 children with intussusception in whom perforation occurred revealed that all had radiologic evidence of bowel obstruction (air-fluid levels) prior to the enema, and the patients had had a relatively long history since the onset of symptoms. No perforation occurred during a delayed repeat enema reduction. Perforation during gas enema produces minimal peritoneal contamination. No pathological lesion at the lead point of the intussusception was identified in any of the children in whom perforation occurred.     

Developmental differences in the effects of repeated interviews and interviewer bias on young children's event memory and false reports.

The present study investigated developmental differences in the effects of repeated interviews and interviewer bias on children's memory and suggestibility. Three- and 5-year-olds were singly or repeatedly interviewed about a play event by a highly biased or control interviewer. Children interviewed once by the biased interviewer after a long delay made the most errors. Children interviewed repeatedly, regardless of interviewer bias, were more accurate and less likely to falsely claim that they played with a man. In free recall, among children questioned once after a long delay by the biased interviewer, 5-year-olds were more likely than were 3-year-olds to claim falsely that they played with a man. However, in response to direct questions, 3-year-olds were more easily manipulated into implying that they played with him. Findings suggest that interviewer bias is particularly problematic when children's memory has weakened. In contrast, repeated interviews that occur a short time after a to-be-remembered event do not necessarily increase children's errors, even when interviews include misleading questions and interviewer bias. Implications for developmental differences in memory and suggestibility are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)