Tunable PDL of twisted-tilted fiber gratings

We fabricated highly tilted fiber gratings and demonstrated that the broad-band polarization-dependent loss (PDL) of the gratings may be tuned by twisting the fiber along the length of the grating. We show that the PDL for a given twist angle can be determined from a simple Jones matrix calculation which can also take into account birefringence on the PDL axis. We combine the twisted-tilted grating with a polarization controller to form a PDL compensator and use it to minimize the polarization-dependent responsivity of a nonlinear silicon avalanche photodiode.     

High scales on the Strong Vocational Interest Blank and the Kuder Occupational Interest Survey using Holland's occupational codes.

Compared the arrays of high-interest occupations produced by the Strong Vocational Interest Blank, T-399, and the Kuder Occupational Interest Survey (Form DD) when the instruments were administered to the same Ss (60 male college students). Holland-type summary codes were devised from the arrays of occupations and were analyzed by correlated t tests and Pearson r correlations. A frequency percentage count showed 85% of the pairs of summary codes had 2 identical characteristics, and some support was found for J. L. Holland's hexagon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recent NASA contributions to biomedical telemetry.

Reviews technological progress that has been made by the National Aeronautics and Space Administration (NASA) in the field of biotelemetry over the past 5 yrs. Emphasis is placed on those developments that have direct applications for human or animal use on earth. Examples of biobelt personal telemetry systems, swallowable telemetry capsules, cardiovascular multichannel implantable telemetry units, and long-range radiotelemetry of biologic data are presented. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceived problem areas by Black and White students and hints about comparative counseling needs.

The Student Problem Areas Survey was administered to 108 Black and 184 White students attending a predominantly White university and to 55 Black students attending a predominantly Black university. Data from a 2-way randomized block design were analyzed by way of the multivariate ANOVA and a series of ANOVAs. The pattern of results shows several significant differences on specific problem areas but none between Blacks attending universities with different racial make-ups nor between the groups on variables that typically suggest counseling needs. There was one Group?×?Class interaction; the ranking of the problem areas was the same for the 3 groups. Results are discussed in terms of their implications for counseling needs of Black students in university settings. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In a resource-poor country, mutation identification has the potential to reduce the cost of family management for hereditary nonpolyposis colorectal cancer

PURPOSE: Colonoscopic surveillance of family members at risk of hereditary nonpolyposis colorectal cancer is difficult in a resource-poor country because of its expense. For family members who live in remote areas, poor communication and limited access to sophisticated medical care make surveillance even more difficult. The identification of the mutation causing the disease will simplify surveillance. Our aim was to assess the impact of mutation analysis on the management of a South African family with more than 150 members at risk for hereditary nonpolyposis colorectal cancer. METHODS: We studied a family that met the Amsterdam criteria for hereditary nonpolyposis colorectal cancer. Colorectal cancer affected 27 members in three generations (evidence from histology in 12, barium enema in 1, and family statements in 14 family members). Leukocyte DNA from family members was tested for linkage to candidate loci for colorectal cancer, and DNA from formalin-fixed cancers from six family members was studied for microsatellite instability. DNA from all available family members was then screened for mutations in the hMLH1 gene. The number of individuals at 50 percent risk was calculated by family pedigree and compared with the number who have the mutation. RESULTS: A disease-causing mutation in exon 13 of hMLH1 segregated with the disorder in members of this kindred. Test results of 100 chromosomes from population-matched controls were negative. Sixty family members between the ages of 16 and 50 years are at 50 percent risk for colon cancer by pedigree analysis, but of these, only 26 (43 percent) have the mutation. CONCLUSION: A mutation in the DNA repair gene hMLH1 was found in family members with hereditary nonpolyposis colorectal cancer and in some unaffected relatives previously at 50 percent risk, but not in unrelated subjects. The blood test for the mutation will simplify management, counseling, and surveillance and help to establish prophylactic colectomy.     

Microinjection of morphine into the nucleus accumbens impairs contextual learning in rats.

A unilateral microinjection of morphine into the amygdala impaired fear conditioning to both a conditioned stimulus (CS) paired with shock and the context where shock occurred, whereas a microinjection of morphine into the nucleus accumbens (NA) spared fear conditioning to the CS but impaired, in a dose-dependent and receptor-specific manner, fear conditioning to the context. Morphine in the NA also spared extinction and latent inhibition of a CS but abolished the context specificity of these effects and eliminated the increase in discriminability that results from preexposure to a to-be-shocked context. The results identify a role for the NA in the processes by which rats learn about a context and are discussed in terms of an opioid disruption of either within-context associations or of attentional processes that contribute to such associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectral properties of strongly coupled 1.5 µm DFB laser diodes

Spectral measurements of strongly coupled DFB lasers operating at 1.5 μm are presented. The magnitude of the coupling coefficientkin these devices was determined to be 80 cm^-1for lasers withlambda = 1.12 mum cladding layers and 160 cm^-1for devices withlambda = 1.3 mum cladding layers. These values forkare believed to be the largest reported for 1.5 μm DFB lasers. CW spectral linewidths as low as 10 MHz at 15 mW output power were obtained, and the linewidth was observed to vary approximately as the inverse of the device length cubed. Spectral measurements performed under 2 Gbit/s direct modulation exhibited a side mode suppression ratio of >38 dB. The effects of transient wavelength chirping were also investigated in detail and the maximum wavelength deviation was found to be ≃1.5 Å.