4,309 research outputs found

    Cold Rearing Improves Cold-Flight Performance in Drosophila Via Changes in Wing Morphology

    Get PDF
    We Use a Factorial Experimental Design to Test Whether Rearing at Colder Temperatures Shifts the Lower Thermal Envelope for Flight of Drosophila Melanogaster Meigen to Colder Temperatures. D. Melanogaster that Developed in Colder Temperatures (15°C) Had a Significant Flight Advantage in Cold Air Compared to Flies that Developed in Warmer Temperatures (28°C). at 14°C, Cold-Reared Flies Failed to Perform a Take-Off Flight ∼47% of the Time Whereas Warm-Reared Flies Failed ∼94% of the Time. at 18°C, Cold- and Warm-Reared Flies Performed Equally Well. We Also Compared Several Traits in Cold- and Warm-Developing Flies to Determine If Cold-Developing Flies Had Better Flight Performance at Cold Temperatures Due to Changes in Body Mass, Wing Length, Wing Loading, Relative Flight Muscle Mass or Wing-Beat Frequency. the Improved Ability to Fly at Low Temperatures Was Associated with a Dramatic Increase in Wing Area and an Increase in Wing Length (After Controlling for Wing Area). Flies that Developed at 15°C Had ∼25% More Wing Area Than Similarly Sized Flies that Developed at 28°C. Cold-Reared Flies Had Slower Wing-Beat Frequencies Than Similarly Sized Flies from Warmer Developmental Environments, Whereas Other Traits Did Not Vary with Developmental Temperature. These Results Demonstrate that Developmental Plasticity in Wing Dimensions Contributes to the Improved Flight Performance of D. Melanogaster at Cold Temperatures, and Ultimately, May Help D. Melanogaster Live in a Wide Range of Thermal Environments

    Continuous Wavelets on Compact Manifolds

    Full text link
    Let M\bf M be a smooth compact oriented Riemannian manifold, and let ΔM\Delta_{\bf M} be the Laplace-Beltrami operator on M{\bf M}. Say 0 \neq f \in \mathcal{S}(\RR^+), and that f(0)=0f(0) = 0. For t>0t > 0, let Kt(x,y)K_t(x,y) denote the kernel of f(t2ΔM)f(t^2 \Delta_{\bf M}). We show that KtK_t is well-localized near the diagonal, in the sense that it satisfies estimates akin to those satisfied by the kernel of the convolution operator f(t2Δ)f(t^2\Delta) on \RR^n. We define continuous S{\cal S}-wavelets on M{\bf M}, in such a manner that Kt(x,y)K_t(x,y) satisfies this definition, because of its localization near the diagonal. Continuous S{\cal S}-wavelets on M{\bf M} are analogous to continuous wavelets on \RR^n in \mathcal{S}(\RR^n). In particular, we are able to characterize the Ho¨\ddot{o}lder continuous functions on M{\bf M} by the size of their continuous S{\mathcal{S}}-wavelet transforms, for Ho¨\ddot{o}lder exponents strictly between 0 and 1. If M\bf M is the torus \TT^2 or the sphere S2S^2, and f(s)=sesf(s)=se^{-s} (the ``Mexican hat'' situation), we obtain two explicit approximate formulas for KtK_t, one to be used when tt is large, and one to be used when tt is small

    Photodeposition of amorphous polydiacetylene films from monomer solutions onto transparent substrates

    Get PDF
    Polydiacetylenes are a very promising class of polymers for both photonic and electronic applications because of their highly conjugated structures. For these applications, high-quality thin polydiacetylene films are required. We have discovered a novel technique for obtaining such films of a polydiacetylene derivative of 2-methyl-4-nitroaniline using photodeposition from monomer solutions onto UV transparent substrates. This heretofore unreported process yields amorphous polydiacetylene films with thicknesses on the order of I micron that have optical quality superior to that of films grown by standard crystal growth techniques. Furthermore, these films exhibit good third-order nonlinear optical susceptibilities; degenerate four-wave mixing experiments give x(3) values on the order of 10(exp -8) - 10(exp -7) esu. We have conducted masking experiments which demonstrate that photodeposition occurs only where the substrate is directly irradiated, clearly indicating that the reaction occurs at the surface. Additionally, we have also been able to carry out photodeposition using lasers to form thin polymer circuits. In this work, we discuss the photodeposition of polydiacetylene thin films from solution, perform chemical characterization of these films, investigate the role of the substrate, speculate on the mechanism of the reaction, and make a preliminary determination of the third-order optical nonlinearity of the films. This simple, straightforward technique may ultimately make feasible the production of polydiacetylene thin films for technological applications

    Investigating the veracity of self-reported post-traumatic growth: a profile analysis approach

    Get PDF
    Research into posttraumatic growth—positive psychological change that people report in their relationships, priorities in life, and self-perception after experiences of adversity—has been severely critiqued. We investigated the degree to which community members’ friends and relatives corroborated targets’ self-perceived positive and negative changes as measured by the Posttraumatic Growth Inventory-42. We found corroboration only for negative changes when we examined overall (averaged) scores. However, using a profile analysis procedure, we found significant participant–informant agreement on the domains of change that had relatively higher scores in the target’s profile and those that had relatively lower scores. Our results demonstrate that informants were able to observe that targets had changed and were sensitive to the idiosyncratic ways in which these changes had manifested in targets’ behavior

    Parity Violation in Elastic Electron-Proton Scattering and the Proton's Strange Magnetic Form Factor

    Get PDF
    We report a new measurement of the parity-violating asymmetry in elastic electron scattering from the proton at backward scattering angles. This asymmetry is sensitive to the strange magnetic form factor of the proton as well as electroweak axial radiative corrections. The new measurement of A=-4.92 +- 0.61 +- 0.73 ppm provides a significant constraint on these quantities. The implications for the strange magnetic form factor are discussed in the context of theoretical estimates for the axial corrections.Comment: 4 pages, 3 figures, submitted to Physical Review Letters, Sept 199

    N-Acetylcysteine improves mitochondrial function and ameliorates behavioral deficits in the R6/1 mouse model of Huntington\u27s disease

    Get PDF
    Huntington\u27s disease (HD) is a neurodegenerative disorder, involving psychiatric, cognitive and motor symptoms, caused by a CAG-repeat expansion encoding an extended polyglutamine tract in the huntingtin protein. Oxidative stress and excitotoxicity have previously been implicated in the pathogenesis of HD. We hypothesized that N-acetylcysteine (NAC) may reduce both excitotoxicity and oxidative stress through its actions on glutamate reuptake and antioxidant capacity. The R6/1 transgenic mouse model of HD was used to investigate the effects of NAC on HD pathology. It was found that chronic NAC administration delayed the onset and progression of motor deficits in R6/1 mice, while having an antidepressant-like effect on both R6/1 and wild-type mice. A deficit in the astrocytic glutamate transporter protein, GLT-1, was found in R6/1 mice. However, this deficit was not ameliorated by NAC, implying that the therapeutic effect of NAC is not due to rescue of the GLT-1 deficit and associated glutamate-induced excitotoxicity. Assessment of mitochondrial function in the striatum and cortex revealed that R6/1 mice show reduced mitochondrial respiratory capacity specific to the striatum. This deficit was rescued by chronic treatment with NAC. There was a selective increase in markers of oxidative damage in mitochondria, which was rescued by NAC. In conclusion, NAC is able to delay the onset of motor deficits in the R6/1 model of Huntington\u27s disease and it may do so by ameliorating mitochondrial dysfunction. Thus, NAC shows promise as a potential therapeutic agent in HD. Furthermore, our data suggest that NAC may also have broader antidepressant efficacy

    Signal Transduction Involving the Dmp1 Transcription Factor and its Alteration in Human Cancer

    Get PDF
    Dmp1 (cyclin D-interacting myb-like protein 1; also called Dmtf1) is a transcription factor that has been isolated in a yeast two-hybrid screen through its binding property to cyclin D2. Dmp1 directly binds to and activates the Arf promoter and induces Arf-p53-dependent cell cycle arrest in primary cells. D-type cyclins usually inhibit Dmp1-mediated transcription in a Cdk-independent fashion; however, Dmp1 shows synergistic effects with D-cyclins on the Arf promoter. Ras or Myc oncogene-induced tumor formation is accelerated in both Dmp1+/− and Dmp1−/− mice with no significant differences between Dmp1+/− and Dmp1−/−. Thus, Dmp1 is haplo-insufficient for tumor suppression. Tumors from Dmp1−/− or Dmp1+/− mice often retain wild-type Arf and p53, suggesting that Dmp1 is a physiological regulator of the Arf-p53 pathway. The Dmp1 promoter is activated by oncogenic Ras-Raf signaling, while it is repressed by physiological mitogenic stimuli, overexpression of E2F proteins, and genotoxic stimuli mediated by NF-κB. The human DMP1 gene (hDMP1) is located on chromosome 7q21 and is hemizygously deleted in approximately 40% of human lung cancers, especially those that retain normal INK4a/ARF and P53 loci. Thus, hDMP1 is clearly involved in human carcinogenesis, and tumors with hDMP1 deletion may constitute a discrete disease entity

    Psychosocial correlates of attitudes towards male sexual violence in a sample of financial crime, property crime, general violent, and homicide offenders

    Get PDF
    Whilst those currently serving prison sentences for sexual violence can be identified and receive treatment, the number of prisoners with a history of sexual violence against female partners is unknown. Methods to identify prisoners with a proclivity for such violence and accurately assess the risk they pose before and after incarceration are therefore required. Here, we aimed to assess the level of sexually violent attitudes within dating relationships and to examine their associations with experiences of child abuse and neglect (CAN), psychopathic personality traits, prisonization, number of incarcerations, age, years of schooling, relationship status, and parenting among different types of offenders (financial crime, property crime, general violent, and homicide offenders). Data were collected among a large systematically selected sample of adult male inmates (N = 1,123). We demonstrated that sexual violence-supportive attitudes appear to be a function of child sexual abuse, psychopathic personality traits, and may be developed through early socialisation experiences as well as incarceration. Practical implications of current findings are discussed

    A Guide to Localized Frames and Applications to Galerkin-like Representations of Operators

    Full text link
    This chapter offers a detailed survey on intrinsically localized frames and the corresponding matrix representation of operators. We re-investigate the properties of localized frames and the associated Banach spaces in full detail. We investigate the representation of operators using localized frames in a Galerkin-type scheme. We show how the boundedness and the invertibility of matrices and operators are linked and give some sufficient and necessary conditions for the boundedness of operators between the associated Banach spaces.Comment: 32 page
    corecore