Structure of neodymium sulfate octahydrate

The problems of X-ray crystal structure determination require some type of automatic computing machinery. An evaluation of these problems has lead to the conclusions that a parallel channel relay digital computer operating in conjunction with the standard I. B. M. units will meet the calculation needs of a structure determination and greatly shorten the time and labor involved. A brief description of a relay computer designed to meet these needs has been given. The computer will be able to perform all of the calculations required with the exception of the Patterson and electron density calculations. The latter may be carried out efficiently on standard I. B. M. units

Patterson superposition system for the IBM 7074

A system is described which aids in resolving the N(N-1) peaks that appear on a PATTERSON MAP into the fundamental set of N vectors corresponding to the N atoms

Assessing the eligibility of kidney transplant donors

Organ transplantation is a highly complex decision processthat requires expert decisions. The major problem in a transplantationprocedure is the possibility of the receiver's immune system attack anddestroy the transplanted tissue. It is therefore of capital importance tond a donor with the highest possible compatibility with the receiver, andthus reduce rejection. Finding a good donor is not a straightforward taskbecause a complex network of relations exists between the immunologicaland the clinical variables that inuence the receiver's acceptance of thetransplanted organ. Currently the process of analyzing these variablesinvolves a careful study by the clinical transplant team. The number andcomplexity of the relations between variables make the manual processvery slow. In this paper we propose and compare two Machine Learningalgorithms that might help the transplant team in improving and speedingup their decisions. We achieve that objective by analyzing past real casesand constructing models as set of rules. Such models are accurate andunderstandable by experts

Aptamer-based multiplexed proteomic technology for biomarker discovery

Interrogation of the human proteome in a highly multiplexed and efficient manner remains a coveted and challenging goal in biology. We present a new aptamer-based proteomic technology for biomarker discovery capable of simultaneously measuring thousands of proteins from small sample volumes (15 [mu]L of serum or plasma). Our current assay allows us to measure ~800 proteins with very low limits of detection (1 pM average), 7 logs of overall dynamic range, and 5% average coefficient of variation. This technology is enabled by a new generation of aptamers that contain chemically modified nucleotides, which greatly expand the physicochemical diversity of the large randomized nucleic acid libraries from which the aptamers are selected. Proteins in complex matrices such as plasma are measured with a process that transforms a signature of protein concentrations into a corresponding DNA aptamer concentration signature, which is then quantified with a DNA microarray. In essence, our assay takes advantage of the dual nature of aptamers as both folded binding entities with defined shapes and unique sequences recognizable by specific hybridization probes. To demonstrate the utility of our proteomics biomarker discovery technology, we applied it to a clinical study of chronic kidney disease (CKD). We identified two well known CKD biomarkers as well as an additional 58 potential CKD biomarkers. These results demonstrate the potential utility of our technology to discover unique protein signatures characteristic of various disease states. More generally, we describe a versatile and powerful tool that allows large-scale comparison of proteome profiles among discrete populations. This unbiased and highly multiplexed search engine will enable the discovery of novel biomarkers in a manner that is unencumbered by our incomplete knowledge of biology, thereby helping to advance the next generation of evidence-based medicine

Silica burial enhanced by iron limitation in oceanic upwelling margins

In large swaths of the ocean, primary production by diatoms may be limited by the availability of silica, which in turn limits the biological uptake of carbon dioxide. The burial of biogenic silica in the form of opal is the main sink of marine silicon. Opal burial occurs in equal parts in iron-limited open-ocean provinces and upwelling margins, especially the eastern Pacific upwelling zone. However, it is unclear why opal burial is so efficient in this margin. Here we measure fluxes of biogenic material, concentrations of diatom-bound iron and silicon isotope ratios using sediment traps and a sediment core from the Gulf of California upwelling margin. In the sediment trap material, we find that periods of intense upwelling are associated with transient iron limitation that results in a high export of silica relative to organic carbon. A similar correlation between enhanced silica burial and iron limitation is evident in the sediment core, which spans the past 26,000 years. A global compilation also indicates that hotspots of silicon burial in the ocean are all characterized by high silica to organic carbon export ratios, a diagnostic trait for diatoms growing under iron stress. We therefore propose that prevailing conditions of silica limitation in the ocean are largely caused by iron deficiency imposing an indirect constraint on oceanic carbon uptake

Alongshore variability of the California Current System from Central to Baja California in winter and spring 2003, physical, chemical and biological properties

Poster.-- American Society of Limnology and Oceanography and the Oceanography Society, Honolulu, Hawaii (USA), 15-20 febrero 2004Sixteen stations along the continental slope of western North America were occupied in February 18-27 and May 22-31, 2003, and form a meridional section from Monterey Bay, California (37º N, 122º W) to Cabo San Lucas, Mexico (23º N, 110º W). Our purpose was to compare trends in California Current (CC), Inshore Countercurrent (ICC) and California Undercurrent (CUC) properties with latitude, and between winter and spring conditions. In winter, coastal upwelling was near zero and the along-transect dynamic height was high and flat, allowing the ICC to advect tropical properties northward. In spring, coastal upwelling had commenced and surface flow along the transect presumably became equatorward. As a consequence of these dynamics, in winter the thermocline was deeper, SST was higher, macronutrients, chlorophyll and primary production were low along the entire transect, with most properties lacking strong latitudinal trends. In spring, the thermocline, macronutrients, chlorophyll and primary production rose along the entire section but most dramatically in the north where upwelling was stronger. Prochlorophytes and other small open-ocean phytoplankton were more abundant in winter along the entire transect and to the south in spring, whereas diatoms, a characteristic coastal group of phytoplankton, were more abundant in spring and in the north. Surface iron was higher in the north in winter, but lower there in spring, presumably reflecting drawdown by diatoms. These results are detailed in the figure captionsWe would like to express our gratitude to the David and Lucile Packard Foundation for funding this workN