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Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator (BC454)/bismuth germanate (BGO) phoswich detector array. Boron-loaded plastic combines neutron moderation (H) and detection ({sup 10}B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on an event-by-event basis using custom integrator and timing circuits, enabling a prompt coincidence requirement between the BC454 and BGO to be used to identify neutron captures. In addition, a custom time-tag module was used to provide a time for each detector event. Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates.

The high precision gamma-ray spectrometer (PGS) is scheduled to be launched on the Russian MARS mission in 1996, and to go into an elliptical polar orbit around Mars. The PGS consists of two high-purity germanium detectors, associated electronics, and a passive cooler and will be deployed from one of the solar panels. The PGS will measure nuclear gamma-ray emissions from the Martian surface, cosmic gamma-ray bursts, and the high-energy component of solar flares in the broad energy range from 50 keV to 8 MeV in 4096 energy channels. The first results are presented of development, integration and qualification of the instrument, both for the passive cooler and for the detector with spectrometric electronics.

Bats possess a genome approximately 50-87% the size of other eutherian mammals. We document that the events that have achieved or maintained a small genome size in the Mexican leaf-nosed bat Macrotus waterhousii have resulted in a lower copy number of interspersed and tandemly repetitive elements. These conclusions are based on examination of 1726 randomly chosen recombinant cosmids, with an average insert size of 35.7 kb and representing 2.6% of the haploid genome of M. waterhousii. Probes representative of microsatellites [(GT)n, (CT)n, (AT)n, (GC)n] and a tandem repeat (rDNA) were used to estimate frequency of repetitive elements in the M. waterhousii genome. Of the four dinucleotides, (GT)n was present in 33.5% of the clones, (CT)n was present in 31.0% of the clones, and (AT)n and (GC)n were not represented in any of the clones examined. The 28S rDNA and a repetitive element from M. californicus were found in three and four clones, respectively. The dinucleotides (GT)n and (CT)n occurred together in the same clone more frequently than expected from chance. Although our data do not allow us to empirically test which mechanisms are maintaining copy number of repetitive DNA in the bat genome, the nonrandom association of these different families of repetitive DNA may provide insight into a mechanism that proportionately reduces diverse families of repetitive DNA that are known to be amplified by very different mechanisms.

The high precision gamma-ray spectrometer (PGS) is scheduled to be launched on the Mars-94 mission in October, 1994, and to go into an elliptical polar orbit around Mars. The PGS consists of two high-purity germanium (Ge) detectors, associated electronics, and a passive cooler and will be mounted on one of the solar panels. The PGS will measure nuclear gamma-ray emissions from the martian surface, cosmic gamma-ray bursts, and the high-energy component of solar flares in the broad energy range from 50 keV to 8 MeV using 4096 energy channels.

[1] Gamma-Ray, Neutron, and Alpha-Particle Spectrometers (GRS, NS, and APS, respectively) were included in the payload complement of Lunar Prospector (LP). Specific objectives of the GRS were to map abundances of Fe, Ti, Th, K, Si, O, Mg, Al, and Ca to depths of 20 cm. Those of the NS were to search for water ice to depths of 100 cm near the lunar poles and to map regolith maturity. Objectives of the APS were to search for, map, and provide a measure of the time history of gaseous release events at the lunar surface. The purpose of this paper is to document the mechanical, analog electronic, digital electronic, and microprocessor designs of the suite of spectrometers, present a representative sample of the calibrated response functions of all sensors, and document the operation of all three LP spectrometers in sufficient detail as to enable the full knowledgeable use of all data products that were archived in the Planetary Data System for future use by the planetary-science community.

[1] The energy spectrum of fast neutrons generated by interactions between galactic cosmic rays and the Mars Odyssey spacecraft during quiet interplanetary conditions is determined. It is given by Φn(En) = (0.071 ± 0.0044) En−(0.28±0.055) cm−2 s−1 MeV−1 for energies between 0.7 and 6 MeV. The estimated ratio of this component of spacecraft neutron background to the Martian leakage flux in Mars orbit is expected to amount to between 0.30 and 0.34. This fraction is sufficiently small so that the total background in orbit about Mars is expected to be dominated by Martian leakage neutrons reprocessed by the spacecraft. Nevertheless, the measured asymmetry properties of the Odyssey Neutron Spectrometer response function should allow separation of foreground and background neutron fluxes when in Mars orbit. The fast neutron flux between 0.7 and 6 MeV should only contribute 0.40 Roentgen Equivalent Man (rem) per year to the total radiation dose aboard a Mars Odyssey class spacecraft at solar maximum.

We constructed a subgenomic cosmid library of DNA replicated early in the S phase of normal human diploid fibroblasts. Cells were synchronized by release from confluence arrest and incubation in the presence of aphidicolin. Bromodeoxyuridine (BrdUrd) was added to aphidicolin-containing medium to label DNA replicated as cells entered S phase. Nuclear DNA was partially digested with Sau 3AI, and hybrid density DNA was separated in CsCl gradients. The purified early-replicating DNA was cloned into sCos1 cosmid vector. Clones were transferred individually into the wells of 96 microtiter plates (9,216 potential clones). Vigorous bacterial growth was detected in 8,742 of those wells. High-density colony hybridization filters (1, 536 clones/filter) were prepared from a set of replicas of the original plates. Bacteria remaining in the wells of replica plates were combined, mixed with freezing medium, and stored at -80 degrees C. These pooled stocks were analyzed by polymerase chain reaction to determine the presence of specific sequences in the library. Hybridization of high-density filters was used to identify the clones of interest, which were retrieved from the frozen cultures in the 96-well plates. In testing the library for the presence of 14 known early-replicating genes, we found sequences at or near 5 of them: APRT, beta-actin, beta-tubulin, c-myc, and HPRT. This library is a valuable resource for the isolation and analysis of certain DNA sequences replicated at the beginning of S phase, including potential origins of bidirectional replication.

A cosmid library made from brown-headed cowbird (Molothrus ater) DNA was examined for representation of 17 distinct microsatellite motifs including all possible mono-, di-, and trinucleotide microsatellites, and the tetranucleotide repeat (GATA)n. The overall density of microsatellites within cowbird DNA was found to be one repeat per 89 kb and the frequency of the most abundant motif, (AGC)n, was once every 382 kb. The abundance of microsatellites within the cowbird genome is estimated to be reduced approximately 15-fold compared to humans. The reduced frequency of microsatellites seen in this study is consistent with previous observations indicating reduced numbers of microsatellites and other interspersed repeats in avian DNA. In addition to providing new information concerning the abundance of microsatellites within an avian genome, these results provide useful insights for selecting cloning strategies that might be used in the development of locus-specific microsatellite markers for avian studies.

Various types of physical mapping data were assembled by developing a set of computer programs (Integrated Mapping Package) to derive a detailed, annotated map of a 4-Mb region of human chromosome 13 that includes the BRCA2 locus. The final assembly consists of a yeast artificial chromosome (YAC) contig with 42 members spanning the 13q12-13 region and aligned contigs of 399 cosmids established by cross-hybridization between the cosmids, which were selected from a chromosome 13-specific cosmid library using inter-Alu PCR probes from the YACs. The end sequences of 60 cosmids spaced nearly evenly across the map were used to generate sequence-tagged sites (STSs), which were mapped to the YACs by PCR. A contig framework was generated by STS content mapping, and the map was assembled on this scaffold. Additional annotation was provided by 72 expressed sequences and 10 genetic markers that were positioned on the map by hybridization to cosmids.

Short, synthetic oligonucleotide sequences representing microsatellites and other short tandem repeats can be elongated (concatamerized) using a simple method in which complementary strands are annealed, phosphorylated, primer extended and ligated. When used in direct-label chemiluminescent hybridizations, the elongated microsatellite sequences provide an approximately 30-fold increase in signal strength compared with microsatellite oligomers that have not been concatamerized. Concatamerization of simple repeat oligomers further enables the use of relatively short oligonucleotide sequences in direct-label chemiluminescent hybridization experiments, thereby reducing the overall need for radioisotopes in certain commonly performed laboratory procedures such as DNA fingerprinting and selection of clones containing microsatellite sequences.

A cosmid library specific for human chromosome 11 has been constructed from flow-sorted chromosomes. The flow-purified chromosomes were prepared from the hamster/human hybrid line J1 which contains chromosome 11 as the only human chromosome. Individual clones were sampled in 187 microtitre plates, resulting in a total of 17 952 colonies. Hybridization analysis revealed that 83.7% of these clones were of human and 10.4% of hamster origin. The average insert size was estimated at 33.6 kb, and only 2.4% of insert fragments appear to be rearranged. This should result in 494 487 kb of cloned human DNA representing 3.5 chromosome 11 equivalents. We have prepared high-density nylon membranes of the arrayed library containing 1 536 single colonies per filter. We have demonstrated the usefulness of the library in the molecular genetic analysis of human chromosome 11 by testing for the presence of possibly polymorphic simple repeat motifs, by identifying cosmids that contain inserts from the telomeric ends of chromosome 11 and by assessing the potential of the library for rapid chromosome walking.

The M13 repeat detects different levels of genetic variation in falcons. First, this minisatellite probe reveals typically highly variant restriction fragments that show no apparent unequal distribution between the sexes. Secondly, the M13 repeat detects sets of fragments that are only present in DNAs from female falcons. The level of polymorphism displayed by the sex-linked fragments is greatly reduced relative to most autosomal minisatellites. In addition, the size of these fragments (in kilobase pairs) is species-specific among Mauritius kestrels (Falco punctatus) and peregrines (Falco peregrinus). Variation observed at one o of the sex-linked fragments in peregrines has proven to be useful in distinguishing a subset of the tundrius subspecies of this endangered raptor. This correlation has enabled a genetic test to be used to examine the representation of tundrius peregrines during mass migration.

Cadmium resistant (Cdr) variants with coordinately amplified metallothionein I and II (MTI and MTII) genes have been derived from both Chinese hamster ovary and near-euploid Chinese hamster cell lines. Cytogenetic analyses of Cdr variants consistently revealed breakage and rearrangement involving chromosome 3p. In situ hybridization with a Chinese hamster MT-encoding cDNA probe localized amplified MT gene sequences near the translocation breakpoint involving chromosome 3p. These observations suggested that both functionally related, isometallothionein loci are linked on Chinese hamster chromosome 3. Southern blot analyses of DNAs isolated from a panel of Chinese hamster X mouse somatic cell hybrids which segregate hamster chromosomes confirmed that both MTI and MTII are located on chromosome 3. We speculate that rearrangement of chromosome 3p could be causally involved with the amplification of MT genes in Cdr hamster cell lines.

An analysis of demand for concentrate feed using a large representative farm model of British agriculture is reported. The model, developed at the University of Newcastle upon Tyne, is modified to link explicitly animal feed manufacturing to the representative farms. Static demand functions for concentrate feed are generated and these are found to be more responsive to price than obtained in a previous econometric study. Some interrelationships between concentrate feeds and livestock categories are presented and a feature is the changing responsiveness at different price relativities. It is concluded that aggregative programming analysis has a role in analysing wider relationships not readily modelled with econometrics, but that the elasticities generated in this study cannot be directly employed for forecasting. Resume LA DEMANDE EN PRODUITS D'ALIMENTATION ANIMALE CONCENTReS DANS L'AGRICULTURE BRITANIQUE—APPROCHE DE PROGRAMMATION AGREGATIVE Cet article rend compte d'une analyse de la demande en produits concentres d'alimentation animale effectuee a l'aide d'un grand modele representatif d'exploitation agricole britannique. Ce modele, concu a Newcastle upon Tyne, est modifie de maniere a relier explicitement la fabrication des aliments du betail aux exploitations representatives. L'on obtient des fonctions statiques de la demande en produits concentres et l'on constate qu'elles reagissent mieux aux prix que celles obtenues dans une precedente etude econometrique. Certaines interrelations sont presentees entre les produits concentres et les categories de betail et l'on note en particulier les variations de la reaction selon les differentes relativites de prix. L'article conclut que l'analyse reposant sur la programmation globale a un role a jouer en ce qui concerne les relations deplus grande dimension pour lesquelles on ne dispose pas de modeles econometriques adequats mais il constate aussi que les elasticites produites par cette etude ne peuvent ětre employees directement pour servir aux previsions. Zusammenfassung DIE NACHFRAGE NACH KONZENTRATFUTTER IN DER BRITISCHEN LANDWIRTSCHAFT: EIN AGGREGATIVES PROGRAMMIERUNGSVERFAHREN Eine Analyse der Nachfrage nach Konzentratfutter wird mit Hilfe eines grofien reprasentativen Farmmodells der britischen Landwirtschaft beschrieben. Dos Modell, das in Newcastle upon Tyne entwickelt wurde, wird modifiziert, um ausdrucklich die Tierfutterherstellung mit den reprasentativen Farmen zu verbinden. Statische Nachfragefunktionen fur Konzentratfutter werden erstellt, und diese erweisen sich als starker auf Preise reagierend als es in fruheren okonometrischen Studien gezeigt wurde. Einige Wechselbeziehungen zwischen Konzentratfutter und Viehkategorien werden aufgezeigt, und ein Merkmal ist die sich andernde Reaktion bei verschiedenen Preisrelatmtuten. Es wirdgefolgert, dafi die aggregierteProgrammierungsanalyse eine Bedeutung fur die Analyse weiterer Beziehungen hat, die sich nicht leicht in der ukonometrie zu Modellen aufstellen lassen, aber dafi die ElastizitQten, die in dieser Studie aufgestellt werden, nicht direkt fur die Vorhersage benutzt werden konnen.

The development and use of two optical fiber systems for the Antares 40 kJ CO2 laser is described. In the Antares power amplifier, electron guns produce a discharge sustaining 8 kA beam of 500 kV electrons. Eight 300 kJ, 3 μs Marx pulsers provide a direct electrical pumping discharge through the laser gas. The electro-optic systems developed allow the measurement of pulsed analog waveforms and trigger timing information within the laser and power systems by a computer based control and data acquisition network.* Each fiber optic system consists of a signal powered transmitter, a fiber optic cable, and an optical receiver that interfaces through a CAMAC module to the data acquisition network. The data channels are capable of operating with 1.2 MV of common mode voltage in the electromagnetic interference environment, 500 kV/m and 50 kA/m, produced by the Marx pulsers. The analog transmitters send 10 MHz bandwidth information to CAMAC waveform digitizers in the data acquisition system. About 200 data channels monitor voltage and current in the pulsers and current density in the laser power amplifiers. The laser transmitters send 2 ns resolution timing information from each stage of the Marx trigger amplification and the Marx output to CAMAC time-to-digital converters. These 120 channels of information are processed to provide prefire diagnostics for the energy storage systems.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We describe an experimental flight validation payload for detecting atmospheric and space nuclear events with a planned launch date in 2004. The five detector subsystems in the payload employ 27 sensors including Si, CdZnTe, gas proportional counter tubes, photomultiplier tubes, channel electron multipliers and photodiodes. Detection of events is based on simultaneous measurements of gamma rays, neutrons, and charged particles with wide dynamic ranges of deposited energy and count rates. The sensors and electronics are housed in one package with approximate mass and power consumption of 27 kg and 50 watts, respectively. The instrument uses sophisticated on-board digital signal processing and multi-layer triggering algorithms to detect and assess the validity of small signals in a large background radiation environment. This paper presents system configuration and preliminary test data from the first of the two units in development.

The Mars Odyssey Gamma-Ray Spectrometer is a suite of three different instruments, a gamma subsystem (GS), a neutron spectrometer, and a high-energy neutron detector, working together to collect data that will permit the mapping of elemental concentrations on the surface of Mars. The instruments are complimentary in that the neutron instruments have greater sensitivity to low amounts of hydrogen, but their signals saturate as the hydrogen content gets high. The hydrogen signal in the GS, on the other hand, does not saturate at high hydrogen contents and is sensitive to small differences in hydrogen content even when hydrogen is very abundant. The hydrogen signal in the neutron instruments and the GS have a different dependence on depth, and thus by combining both data sets we can infer not only the amount of hydrogen, but constrain its distribution with depth. In addition to hydrogen, the GS determines the abundances of several other elements. The instruments, the basis of the technique, and the data processing requirements are described as are some expected applications of the data to scientific problems.