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Reports on research into the ways visual maps work in the brains of monkeys. Reasons maps exist; Anthropologist John Allman's study of primate brains; Study of hedgehog visual maps; Brain's mechanisms for interpreting images in the cat; Study of complexity of association area cells; Research on the owl monkey; Role of repetitive maps; Color-sensitive blobs; Nerve connections; Role in learning and memory.

Reports on recent findings concerning the ability of birds to regenerate their brains' nerve cells. Zoologist Fernando Nottebohm's research with canaries; Research towards discovering how human brains may regenerate.

Discusses research which is using viruses, nature's genetic parasites, to carry beneficial genes into sick cells, or gene therapy, and its applications for treatment of genetic disorders. Studies of hemoglobin; Problems facing researchers; Retroviral trucks; Switches and enhancers; First human gene transplant; Drawbacks of gene therapy.

Discusses the research of neurobiologist Eric Kandel into the molecular processes that enable our nerve cells to store information. Focus on Kandel's experiments with the Aplysia, a California marine snail; Kandel's background and career development; Experiments conducted to-date; Theories propounded.

Describes postdoctoral fellow in immunology at Stanford University Mike McCune's development of a mouse that has the immune system of a human and will be used as a model for studying AIDS. Co-founder of the bio-tech firm, SyStemix; How the human immune system was transplanted into mice born with severe combined immunodeficiency (SCID); Infecting the SCID-hu mice with the AIDS virus.

Discusses the retinex theory of color constancy made by Edwin Land, former head of Polaroid, and biologists' research on how the eye and brain see color. How Land first discovered the computational approach to color vision; Retinal neurons respond to a color and the color that surrounds it making a comparison between them; Research on the visual cortex. INSET: Color blindness and evolution..

Biologists, such as Paul Sternberg of Massachusetts Institute of Technology, Boston, Mass., are witnessing how mutations in genes alter the development of an organism. Programmed cell death is a crucial tool of evolution. Cell lineage of worms is described. Heterochromic mutations. INSET: Caenorhabditis Genetics Center of the University of Missouri..

The article discusses issues concerning products safety and energy consumption in the U.S. The Congress has passed a bill which calls on various Federal agencies to establish certain standards for the performances of appliance products. The Center for Consumer Product Technology assures consumer to provide enough information on the durability and efficiency of appliances. The establishment of the labeling system for certain appliances made by the National Bureau of Standards aims to ascertain the consumer about the efficiency of the appliance.

Purpose: To examine the effectiveness of prophylaxis with respiratory syncytial virus (RSV) monoclonal antibody in reducing the incidence of hospitalization due to respiratory syncytial virus infection in high-risk infants and [...]

The diathesis–stress theory for depression states that the effects of stress on the depression risk are dependent on the diathesis or vulnerability, implying multiplicative interactive effects on the liability scale. We used polygenic risk scores for major depressive disorder (MDD) calculated from the results of the most recent analysis from the Psychiatric Genomics Consortium as a direct measure of the vulnerability for depression in a sample of 5221 individuals from 3083 families. In the same we also had measures of stressful life events and social support and a depression symptom score, as well as DSM-IV MDD diagnoses for most individuals. In order to estimate the variance in depression explained by the genetic vulnerability, the stressors and their interactions, we fitted linear mixed models controlling for relatedness for the whole sample as well as stratified by sex. We show a significant interaction of the polygenic risk scores with personal life events (0.12% of variance explained, P-value=0.0076) contributing positively to the risk of depression. Additionally, our results suggest possible differences in the aetiology of depression between women and men. In conclusion, our findings point to an extra risk for individuals with combined vulnerability and high number of reported personal life events beyond what would be expected from the additive contributions of these factors to the liability for depression, supporting the multiplicative diathesis–stress model for this disease.

Despite moderate heritability, only one study has identified genome-wide significant loci for cannabis-related phenotypes. We conducted meta-analyses of genome-wide association study data on 2080 cannabis-dependent cases and 6435 cannabis-exposed controls of European descent. A cluster of correlated single-nucleotide polymorphisms (SNPs) in a novel region on chromosome 10 was genome-wide significant (lowest P=1.3E−8). Among the SNPs, rs1409568 showed enrichment for H3K4me1 and H3K427ac marks, suggesting its role as an enhancer in addiction-relevant brain regions, such as the dorsolateral prefrontal cortex and the angular and cingulate gyri. This SNP is also predicted to modify binding scores for several transcription factors. We found modest evidence for replication for rs1409568 in an independent cohort of African American (896 cases and 1591 controls; P=0.03) but not European American (EA; 781 cases and 1905 controls) participants. The combined meta-analysis (3757 cases and 9931 controls) indicated trend-level significance for rs1409568 (P=2.85E−7). No genome-wide significant loci emerged for cannabis dependence criterion count (n=8050). There was also evidence that the minor allele of rs1409568 was associated with a 2.1% increase in right hippocampal volume in an independent sample of 430 EA college students (fwe-P=0.008). The identification and characterization of genome-wide significant loci for cannabis dependence is among the first steps toward understanding the biological contributions to the etiology of this psychiatric disorder, which appears to be rising in some developed nations.

The μ-opioid receptor (MOR) is the primary target of methadone and buprenorphine. The primary neuronal transcript of the OPRM1 gene, MOR-1, contains a ~13 kb 3′ untranslated region with five common haplotypes in European-Americans. We analyzed the effects of these haplotypes on the percentage of opioid positive urine tests in European-Americans (n=582) during a 24-week, randomized, open-label trial of methadone or buprenorphine/naloxone (Suboxone) for the treatment of opioid dependence. A single haplotype, tagged by rs10485058, was significantly associated with patient urinalysis data in the methadone treatment group. Methadone patients with the A/A genotype at rs10485058 were less likely to have opioid-positive urine drug screens than those in the combined A/G and G/G genotypes group (relative risk=0.76, 95% confidence intervals=0.73–0.80, P=0.0064). Genotype at rs10485058 also predicted self-reported relapse rates in an independent population of Australian patients of European descent (n=1215) who were receiving opioid substitution therapy (P=0.003). In silico analysis predicted that miR-95-3p would interact with the G, but not the A allele of rs10485058. Luciferase assays indicated miR-95-3p decreased reporter activity of constructs containing the G, but not the A allele of rs10485058, suggesting a potential mechanism for the observed pharmacogenetic effect. These findings suggest that selection of a medication for opioid dependence based on rs10485058 genotype might improve outcomes in this ethnic group.

Genotyping of large populations through genome-wide association studies (GWAS) has successfully identified many genomic variants associated with traits or disease risk. Unexpectedly, a large proportion of GWAS single nucleotide polymorphisms (SNPs) and associated haplotype blocks are in intronic and intergenic regions, hindering their functional evaluation. While some of these risk-susceptibility regions encompass cis-regulatory sites, their transcriptional potential has never been systematically explored. To detect rare tissue-specific expression, we employed the transcript-enrichment method CaptureSeq on 21 human tissues to identify 1775 multi-exonic transcripts from 561 intronic and intergenic haploblocks associated with 392 traits and diseases, covering 73.9 Mb (2.2%) of the human genome. We show that a large proportion (85%) of disease-associated haploblocks express novel multi-exonic non-coding transcripts that are tissue-specific and enriched for GWAS SNPs as well as epigenetic markers of active transcription and enhancer activity. Similarly, we captured transcriptomes from 13 melanomas, targeting nine melanoma-associated haploblocks, and characterized 31 novel melanoma-specific transcripts that include fusion proteins, novel exons and non-coding RNAs, one-third of which showed allelically imbalanced expression. This resource of previously unreported transcripts in disease-associated regions (http://gwas-captureseq.dingerlab.org) should provide an important starting point for the translational community in search of novel biomarkers, disease mechanisms, and drug targets.

Anxiety disorders (ADs), namely generalized AD, panic disorder and phobias, are common, etiologically complex conditions with a partially genetic basis. Despite differing on diagnostic definitions based on clinical presentation, ADs likely represent various expressions of an underlying common diathesis of abnormal regulation of basic threat–response systems. We conducted genome-wide association analyses in nine samples of European ancestry from seven large, independent studies. To identify genetic variants contributing to genetic susceptibility shared across interview-generated DSM-based ADs, we applied two phenotypic approaches: (1) comparisons between categorical AD cases and supernormal controls, and (2) quantitative phenotypic factor scores (FS) derived from a multivariate analysis combining information across the clinical phenotypes. We used logistic and linear regression, respectively, to analyze the association between these phenotypes and genome-wide single nucleotide polymorphisms. Meta-analysis for each phenotype combined results across the nine samples for over 18?000 unrelated individuals. Each meta-analysis identified a different genome-wide significant region, with the following markers showing the strongest association: for case–control contrasts, rs1709393 located in an uncharacterized non-coding RNA locus on chromosomal band 3q12.3 (P=1.65 × 10-8); for FS, rs1067327 within CAMKMTencoding the calmodulin-lysine N-methyltransferase on chromosomal band 2p21 (P=2.86 × 10-9). Independent replication and further exploration of these findings are needed to more fully understand the role of these variants in risk and expression of ADs.

Inbreeding depression refers to lower fitness among offspring of genetic relatives. This reduced fitness is caused by the inheritance of two identical chromosomal segments (autozygosity) across the genome, which may expose the effects of (partially) recessive deleterious mutations. Even among outbred populations, autozygosity can occur to varying degrees due to cryptic relatedness between parents. Using dense genome-wide single-nucleotide polymorphism (SNP) data, we examined the degree to which autozygosity associated with measured cognitive ability in an unselected sample of 4854 participants of European ancestry. We used runs of homozygosity—multiple homozygous SNPs in a row—to estimate autozygous tracts across the genome. We found that increased levels of autozygosity predicted lower general cognitive ability, and estimate a drop of 0.6 s.d. among the offspring of first cousins (P=0.003–0.02 depending on the model). This effect came predominantly from long and rare autozygous tracts, which theory predicts as more likely to be deleterious than short and common tracts. Association mapping of autozygous tracts did not reveal any specific regions that were predictive beyond chance after correcting for multiple testing genome wide. The observed effect size is consistent with studies of cognitive decline among offspring of known consanguineous relationships. These findings suggest a role for multiple recessive or partially recessive alleles in general cognitive ability, and that alleles decreasing general cognitive ability have been selected against over evolutionary time.

Opioid dependence, a severe addictive disorder and major societal problem, has been demonstrated to be moderately heritable. We conducted a genome-wide association study in Comorbidity and Trauma Study data comparing opioid-dependent daily injectors (N=1167) with opioid misusers who never progressed to daily injection (N=161). The strongest associations, observed for CNIH3single-nucleotide polymorphisms (SNPs), were confirmed in two independent samples, the Yale-Penn genetic studies of opioid, cocaine and alcohol dependence and the Study of Addiction: Genetics and Environment, which both contain non-dependent opioid misusers and opioid-dependent individuals. Meta-analyses found five genome-wide significant CNIH3SNPs. The A allele of rs10799590, the most highly associated SNP, was robustly protective (P=4.30E-9; odds ratio 0.64 (95% confidence interval 0.55–0.74)). Epigenetic annotation predicts that this SNP is functional in fetal brain. Neuroimaging data from the Duke Neurogenetics Study (N=312) provide evidence of this SNP’s in vivofunctionality; rs10799590 A allele carriers displayed significantly greater right amygdala habituation to threat-related facial expressions, a phenotype associated with resilience to psychopathology. Computational genetic analyses of physical dependence on morphine across 23 mouse strains yielded significant correlations for haplotypes in CNIH3and functionally related genes. These convergent findings support CNIH3involvement in the pathophysiology of opioid dependence, complementing prior studies implicating the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate system.

Cognitive impairment is common among individuals diagnosed with autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). It has been suggested that some aspects of intelligence are preserved or even superior in people with ASD compared with controls, but consistent evidence is lacking. Few studies have examined the genetic overlap between cognitive ability and ASD/ADHD. The aim of this study was to examine the polygenic overlap between ASD/ADHD and cognitive ability in individuals from the general population. Polygenic risk for ADHD and ASD was calculated from genome-wide association studies of ASD and ADHD conducted by the Psychiatric Genetics Consortium. Risk scores were created in three independent cohorts: Generation Scotland Scottish Family Health Study (GS:SFHS) (n=9863), the Lothian Birth Cohorts 1936 and 1921 (n=1522), and the Brisbane Adolescent Twin Sample (BATS) (n=921). We report that polygenic risk for ASD is positively correlated with general cognitive ability (beta=0.07, P=6 × 10−7, r2=0.003), logical memory and verbal intelligence in GS:SFHS. This was replicated in BATS as a positive association with full-scale intelligent quotient (IQ) (beta=0.07, P=0.03, r2=0.005). We did not find consistent evidence that polygenic risk for ADHD was associated with cognitive function; however, a negative correlation with IQ at age 11 years (beta=−0.08, Z=−3.3, P=0.001) was observed in the Lothian Birth Cohorts. These findings are in individuals from the general population, suggesting that the relationship between genetic risk for ASD and intelligence is partly independent of clinical state. These data suggest that common genetic variation relevant for ASD influences general cognitive ability.

Samples of arthropods in canopies of selected trees were collected by pyrethrum-fogging during the early part of the 1977 dry season from three types of neotropical forest: varzea and igapo forest which are inundated seasonally by white-water and black-water rivers respectively, and terra firme forest which is not subject to inundation. Sampling areas were within 30 km of Manaus, Brazil. Number and biomass of arthropods sampled was highest in terra firme, intermediate in igapo and lowest in varzea. Ants were dominant on all sites and a high percentage of their species were found only in one type of forest. It is considered that many taxa are incompletely sampled with the fogging technique. Further statements on the canopy fauna of Central Amazonian forest types should be based on fogging data gathered from all seasons and compared with material sampled with other methods at the same time and locality.

This paper describes light control films consisting of submicron liquid crystal droplets dispersed in epoxy matrices. These films, which can respond optically to both applied electric fields and temperature changes, are potentially useful for displays and light shutters.The optical performance of these films depends on a variety of structural, electrooptical and thermal properties. This paper describes scanning electron microscope studies of film structure, measurements of voltage dependent film transmittance, contrast ratio and light scattering, and calorimetric studies of the cure process which governs microdroplet formation in the films.

This paper describes a new class of light control films consisting of submicron liquid crystal droplets dispersed in ultraviolct-cured polymer matrices. These films, which can respond optically to both applied electric fields and temperature changes, are potentially useful for displays and light shutters.The optical performance of these films depends on a variety of structural, electro-optical and thermal properties. This report describes scanning electron microscope studies of film structure, measurements of voltage dependent film transmittance and light scattering, and calorimetric studies which indicate that microdroplet formation in the films occurs as a result of phase separation which takes place during the cure process.

Polymer-dispersed liquid crystal (PDLC) films are potentially useful for electronic displays, windows with electrically controllable light transmission, and other applications. PDLC film performance may depend strongly on the angular distribution of the light scattered by the films. We have measured the angular distributions of light scattered by both chemically cured and UV-cured PDLC films as a function of incident and scattered optical polarization. The measured angular dependences differ significantly from those produced by a collection of optically isotropic scatterers: off-diagonal elements of the amplitude scattering matrix are nonzero and comparable in magnitude to the diagonal elements. Furthermore, the scattered intensity for incident light polarized parallel to the scattering plane is not simply related to the scattered intensity for incident light polarized perpendicular to the scattering plane. Comparison of these results with a recent theory of light scattering from a nematic liquid-crystal droplet indicates that multiple scattering is important in PDLC films even in their on state. This multiple scattering is, at least in part, produced by total internal reflection at air-sample interfaces for certain scattering angles. From our polarization-dependent intensity measurements, we have computed the fractions of incident light scattered into the forward and backward hemispheres. The forward-scattered intensity is 2.5–4 times as large as the backscattered intensity for our samples.

The refractive indices of a side-chain polymer liquid crystal, 4-ω-hydroxyhexyl-l-oxy-)-4'-methoxy-α- methylstilbene, polymethacrylate with weight-averaged molecular weight Mw = 54,000 have been measured as a function of temperature using a Jelley-Leitz refractometer. In these measurements the polymer was aligned by shear flow in the nematic phase. We developed a model for this alignment in order to interpret the data in terms of the polarization direction of the refracted light. The results suggest that the polymer is aligned so that one of its minor optical axes (i.e., one of the directions along which one measures the ordinary refractive index) lies along the flow direction and its principal optical axis (i.e., the direction along which one measures the extraordinary refractive index) is distributed in a plane perpendicular to the flow axis.

Polymer-dispersed liquid crystal (PDLC) films are useful in electro-optic applications because they can be switched electrically between opaque and transparent states. We have prepared PDLC films using electron-beam radiation (e-beam cure). The resulting films exhibit promising mechanical, electro-optic, and thermal response. Compared with the ultraviolet cure process, e-beam cure has the advantage of not requiring photoinitiators. In addition, e-beam cure is characterized by a fast cure rate. The e-beam cure method May therefore, be a good candidate for production of PDLC films.

We studied the outcome of ultrasound-monitored Pavlik harness treatment of 47 infants (nine boys and 38 girls) with 55 frankly dislocated hips documented by dynamic ultrasonography. The success and failure groups were of similar ultrasound status (hip-status score) at the time of initial examination, but a significant difference emerged at the 7- and 14-day examinations. Detection of frank dislocation and institution of treatment with the Pavlik harness within 3 weeks of birth increased the probability of a successful result. Of 33 infants (27 girls and six boys) with 41 dislocated hips who were seen before the age of 21 days, 26 (63%) hips were reducible in the Pavlik harness alone, and 15 (37%) hips were irreducible and required a subsequent procedure to achieve reduction. Fourteen infants (three boys and 11 girls) with 14 dislocated hips were first seen after the age of 21 days. Three (20%) were successfully treated in the Pavlik harness alone, and 11 (80%) required further treatment. In our opinion, persistent dislocation without improvement after 3 weeks of treatment in the Pavlik harness mandates discontinuation of use of this device. No anatomic factors were seen at the time of the initial ultrasound examination that permitted prediction of those hips likely to succeed or fail treatment with the Pavlik harness.

We report studies of Pb_1−xSnxTe and Pb_1−xGex Te laser characteristics which affect their performance in high-sensitivity gas analysis. In Pb_1−xSnxTe, the rates at which the energy gap Eg and the individual cavity mode frequencies ν¯ tune with current are consistent with published data. Single-mode operation typically occurs near threshold; at higher currents, multimode operation is common. In Pb_1−xGexTe, Eg and ν¯ tune more slowly, and multimode operation generally occurs. High-resolution absorption measurements on C_2H_4 (950 cm^−1) and NH_3 (931 cm^−1) indicate that the frequency reproducibility of the lasers is adequate for trace gas analysis. Such analysis has been performed on calibrated samples of C_2H_4 in N_2 at atmospheric pressure. The minimum detectable C_2H_4 concentration for a 10-cm path was between 17 ppm and 50 ppm, in good agreement with the 30 ppm estimated for detector-noise-limited operation. Effects of detector and laser noise on detection sensitivity are discussed.

We analyze in detail the on-state optical performance of a liquid-crystal image transducer (LCIT) developed at Hughes Research Laboratories. We first calculate how the 45° twisted nematic configuration of the liquid crystal in the transducer is distorted by an applied electric field. Then, using the results of this calculation, we compute the intensity and phase of the monochromatic output light from the LCIT as a function of transducer parameters and operating conditions. We find that the output light intensity is very sensitive to liquid-crystal thickness and is strongly influenced by other, optically isotropic, layers in the LCIT. We also analyze the phase behavior of the light emerging from the transducer. Our calculations agree very well with the measured phase response. Both theory and experiment predict that a coherent light image produced by the LCIT will have an appreciable phase component which, if properly controlled, might be exploited in optical data-processing applications.

We develop the mathematical procedures for quantitatively describing the optical performance of a liquid-crystal image transducer as a function of transducer parameters and operating conditions. These procedures are based on a 4 × 4 matrix formalism which provides an exact numerical solution of Maxwell’s equations. Our calculations include interference effects arising from the multilayer structure of the transducer and we realistically treat reflection and transmission at isotropic-anisotropic layer boundaries. We compute the off-state optical properties of a twisted nematic reflection-mode transducer developed at Hughes Research Laboratories. We show that the dependence of output light intensity on liquid-crystal thickness is strongly influenced by the optically isotropic layers in the transducer, especially the electrodes. If the liquid-crystal thickness varies across the transducer aperture, these layers can produce a sharp fringe pattern in the output intensity. We also analyze the effect of varying the angle between the input polarization and the director at the entrance face of the liquid-crystal layer. For a given liquid-crystal thickness, there always exists an angle for which the off-state intensity is zero. The sensitivity of off-state intensity to rotation varies with liquid-crystal thickness. Off-state behavior is independent of liquid-crystal pretilt for the range of pretilt angles used in typical transducers.

We have significantly improved the solar attenuation characteristics of ultraviolet-cured polymer-dispersed liquid crystal (PDLC) films by adding chemical accelerators to the materials from which the films are formed. The visual transmittance and response times of the new films are comparable to those of the best ultraviolet-cured films prepared without an accelerator; however, the new films may require higher operating voltages to achieve this performance. In addition, PDLC films prepared with accelerators require approximately 50% less liquid crystal than the best films made without accelerators.

We have studied the effect of dual frequency addressing (DFA) on the number of rows Nmax which can be multiplexed in a liquid crystal display incorporating a PDLC film. Nmax depends strongly on the required contrast ratio. For the film we studied and a contrast ratio of nine, only direct driving is possible without DFA. With DFA and the same contrast ratio, the number of multiplexable rows can be increased to nearly seven. Higher operating voltages are required to obtain this increased multiplexability. At maximum multiplexability, the off-state voltage increases by about 60 Vrms while the on-state voltage increases by less than 30 Vrms; most of the increase is due to the high frequency voltage component needed for DFA. To switch between the off-and the on-states, it is sufficient to switch only the low frequency component of the driving voltage; this can be done with the drivers which would be used in a direct drive mode.

The plasma concentrations of LH and prolactin and various parameters of ovarian function were examined in cows on known days of the oestrous cycle during May and June (autumn and winter) and during October (spring).Luteinizing hormone peak frequency and plasma prolactin concentrations were significantly higher in October than during the May–June period (LH, P<0·05; prolactin, P<0·01). The mean diameters of large healthy follicles (≥8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P<0·01 for both follicle types) and each follicle contained more granulosa cells (both P<0·01) in May–June than in October. The LH responsiveness of theca interna with respect to androstenedione production and the levels of aromatase activity in granulosa cells did not differ with time of year. The corpora lutea were heavier (P<0·05) and secreted more progesterone (P<0·01) in May–June than in October.It is concluded that seasonal differences in ovarian activity exist in cows and that these differences are probably the consequence of seasonal differences in gonadotrophin secretion.J. Endocr.(1984) 102, 189–198

Blood samples were obtained from adult female Weddell seals in McMurdo Sound, Antarctica, utilizing four different seals every 2 h for 24 h on two occasions in November 1987. Plasma levels of melatonin were mostly near zero, whereas the values for cortisol were high (2101 ±54 and 1908 ± 108 (s.e.m.) nmol/l, n= 52). For both hormones there was no evidence of a diurnal pattern of secretion. Juvenile seals sampled in December 1985 also had no evidence of a diurnal secretion pattern of melatonin, but blood levels of melatonin were higher than in adults. The results indicate that secretion of melatonin in adult Weddell seals ceases during the Antarctic summer.Journal of Endocrinology(1989) 122,445–449

Infrared absorption by the water vapor continuum near 1200 cm^−1 has been measured with a lead-tin-telluride diode laser over a 40.5-m optical path. The measurements were made as a function of temperature from 333 K to 473 K; thus, they overlap and extend previous measurements made at temperatures between 293 K and 388 K. Over the entire temperature range studied here, the continuum extinction coefficient increases quadratically with water-vapor partial pressure as expected for the relatively high partial pressures used in these measurements. At temperatures below 398 K, our measured extinction coefficients agree well with previously reported data. At higher temperatures, however, the extinction coefficient is almost independent of temperature and is substantially larger than predicted by empirical formulas. Values of the self-broadening coefficient for water vapor have been extracted from the experimental data, and a possible interpretation of the results involving both dimer and line-broadening effects is presented.

Contrast ratio is an important measure of the performance of an electrooptic display. From measurements of film brightness and transmittance, we determined contrast ratios of thin polymer films containing microdroplets of liquid crystalline material. Contrast ratios based on brightness were typically ~3 for all samples studied, whereas contrast ratios based on transmittance varied from ~20 to 200 depending on the sample. We explain these differences by analyzing the relations between the illumination geometries in the two measurements and the voltage-dependent multiple scattering of light which controls the electrooptic performance of the films. Effects of the spectral content of the light source and the response of the human eye on contrast ratio were also determined. The results presented here demonstrate the importance of standardizing procedures for measuring contrast ratios of these new liquid crystal films.

High-resolution absorption spectra within the central maximum of the v_7 band of C_2H_4 have been recorded using tunable semiconductor lasers. 169 individual transitions have been resolved in three nonoverlapping frequency regions covering approximately 97% of the spectral range from 947.1 to 951.9 cm^-1. The frequency splittings between individual transitions are reproducible to ±0.008 cm^-1 or better. The problems of scanning an extended frequency range with a multiplicity of diode lasers arise primarily from limited laser-tuning range and the lack of appropriate techniques for precise absolute frequency calibration. The strengths and weaknesses of diode lasers in high-resolution molecular spectroscopy are assessed.

The genetic linkage map of sheep Chromosome (Chr) 6 has been extended to include 35 loci with the addition of 11 RFLP and 12 microsatellite loci. The sex-averaged linkage map now spans 154 cM from phosphodiesterase cyclic GMP beta polypeptide (PDE6B) to OarCP125, an anonymous sheep microsatellite. The male and female map lengths, at 180 cM and 132 cM respectively, did not differ significantly. The physical assignment of PDE6Bto Chr 6q33-qter orientates the linkage map on sheep Chr 6 with PDE6Bnear the telomere and OarCP125towards the centromere. The order and genetic distances between loci are similar for the sheep Chr 6 and cattle Chr 6 maps, except for the position of the casein genes. The sheep Chr 6 linkage map is also comparable to portions of human Chr 4, mouse Chrs 5 and 3, and pig Chr 8. The synteny between sheep Chr 6 and human Chr 4 has been extended from PDE6B(4pl6.3) to epidermal growth factor (EGF, 4q25-q27). However, a region from platelet-derived growth factor receptor α polypeptide (PDGFRA) to bone morphogenetic protein 3 (BMP3), which spans 19 cM on sheep Chr 6, appears to be inverted with respect to the human and mouse loci. Other differences in the gene order between sheep, pig, and mouse suggest more complex rearrangements.

High-resolution absorption spectra within the central maximum of the ν_7 band of C_2H_4 have been recorded using tunable semiconductor lasers. 169 individual transitions have been resolved in three nonoverlapping frequency regions covering approximately 97% of the spectral range from 947.1 to 951.9 cm^−1. The frequency splittings between individual transitions are reproducible to ±0.008 cm^−1 or better. The problems of scanning an extended frequency range with a multiplicity of diode lasers arise primarily from limited laser-tuning range and the lack of appropriate techniques for precise absolute frequency calibration. The strengths and weaknesses of diode lasers in high-resolution molecular spectroscopy are assessed.

The autosomal Booroola fecundity gene (FecB) mutation in sheep increases ovulation rate and litter size, with associated effects on ovarian physiology and hormone profiles. Analysis of segregation in twelve families (379 female progeny) identified linkage between the mutation, two microsatellite markers (OarAE101 and OarHH55, Zmax>9.0) and epidermal growth factor (EGF) from human chromosome 4q25 (Zmax>3.0). The marker OarAE101 was linked to secreted phosphoprotein 1 (SPP1, which maps to chromosome 4q21–23 in man) in the test pedigrees and independent families (Zmax>9.7). The identification of linkage between the FecB mutation and markers from human chromosome 4q is an important step towards further understanding the control of ovulation rates in mammals.

Summary.Romney and Perendale ewes were selected on the amplitude of seasonal wool growth. The ewes were fed a constant plane of nutrition and run with vasectomized rams. Ovarian activity was recorded by laparoscopy during 11 months. Ewes with a low amplitude of seasonal wool growth (Group L) had a 68% higher wool growth rate in winter and a 17% lower wool growth rate in summer compared with ewes with a high amplitude (Group H). There was no difference between the groups in the date of the first mating mark. Ewes in Group L entered anoestrus significantly later than did ewes in Group H; the difference was 11 days in the mean date of the last mating mark and 17 days in the mean date of the last ovulation. A significantly higher proportion of ewes in Group L ovulated during July to November. In addition, ewes in Group L had a significantly higher proportion of multiple ovulations throughout the experiment: on average the difference between the groups was 0·21. These results show that phenotypic selection for a low amplitude of seasonal wool growth resulted in a delay in the end of the breeding season associated with an increase in ovulation rate, suggesting independent effects on the beginning and end of the breeding season.

Summary.Bovine cDNA probes for the β-subunit of follicle-stimulating hormone β (FSHβ) and the α-subunit of the glycoprotein hormones identify genetic variation (polymorphic restriction fragments) near these genes in sheep. The inheritance of the polymorphic restriction fragments was studied in half-sibling pedigrees generated by mating heterozygous (B+) rams to non-carrier (++) ewes so that the co-inheritance or genetic linkage to the Booroola (FecB) locus and the α- and β-subunits of FSH could be analysed. Genetic recombination was observed between the FSHβ locus and the FecBlocus in all five families studied and between the α-subunit and the FecBlocus in the two families studied. We conclude that the FecBmutation does not lie within the FSH β- or α-subunit genes encoding the heterodimeric hormone FSH, and that the high concentrations of FSH observed in carrier ewes must result from indirect actions of the FecBmutation on the synthesis, processing, storage, release or metabolism of FSH.Keywords:FSHβ; α-subunit; FecBgene; sheep; Booroola; RFLP analysis; genetic linkage

Summary.Ile-de-France ewes were ovariectomized during anoestrus or the mid-luteal phase of an oestrous cycle (day of ovariectomy = Day 0). In a short-term study, FSH concentrations were measured in blood samples collected hourly the day before and on Days 1, 3, 7 and 15 after ovariectomy (10 ewes per group). FSH concentrations increased significantly from 6·1 to 16·5 ng/ml within 1 day of ovariectomy and increased further to 47·1 ng/ml by Day 15. Differences between seasons of ovariectomy were not significant.In a long-term study, FSH concentrations were measured in blood samples collected hourly on Days 7, 15, 30, 60,90, 120, 150 and 180 after ovariectomy in anoestrus or the breeding season (10 ewes per group). Further samples were taken (5 ewes/group) at 240 and 365 days after ovariectomy. The pattern of change in FSH after ovariectomy differed between the two seasons and the interaction between season and sampling day was significant. For ewes ovariectomized during anoestrus, FSH concentrations increased to a maximum by Day 180 and remained high thereafter. In contrast FSH increased more slowly in ewes ovariectomized in the breeding season and differences between the groups were significant from Day 90 to Day 270. However, both groups had similar FSH concentrations at Day 365.These results show that FSH concentrations increase rapidly after ovariectomy. There are seasonal differences in FSH concentrations in the absence of ovarian feedback with increases in FSH concentration around the time of the onset of the breeding season. Once FSH concentrations had reached a maximum, major seasonal changes were no longer apparent.

Abstract: The addition of54Mn and65Zn to a nine-radionuclide standard (containing241Am.,109Cd.57Co,139Ce,203Hg.113Sn,137Cs,88Y, and60Co) provides the capability to determine the extent of coincidence summing for gamma rays from88Y and60Co. A method for correcting the efficiency points at 1332 keV (60Co) and 1836 keV (88Y) for coincidence summing is presented.

Abstract: The sulphur contents of samples of three types of carrageenan and protein/carrageenan complexes have been determined using simultaneous Deuteron Induced X-ray Emission (DIXE) and Nuclear Reaction Analysis (NRA). The measured relative sulphur contents of the carrageenan samples were in close agreement with those expected from their chemical structures. Analysis of carrageenan precipitated protein/carrageenan complexes, samples not amenable to conventional chemical assays, indicates that precipitation is less efficient at carrageenan levels above 50ppm. At such levels the excess carrageenan remains in solution and represents a waste of a costly resource in a commercial environment.