Quantization of the electromagnetic field outside static black holes and its application to low-energy phenomena

We discuss the Gupta-Bleuler quantization of the free electromagnetic field outside static black holes in the Boulware vacuum. We use a gauge which reduces to the Feynman gauge in Minkowski spacetime. We also discuss its relation with gauges used previously. Then we apply the low-energy sector of this field theory to investigate some low-energy phenomena. First, we discuss the response rate of a static charge outside the Schwarzschild black hole in four dimensions. Next, motivated by string physics, we compute the absorption cross sections of low-energy plane waves for the Schwarzschild and extreme Reissner-Nordstr\"om black holes in arbitrary dimensions higher than three.Comment: 26 pages (revtex), no figures, misprints in some conditions correcte

Theory of Mind, Pragmatic Language, and Social Skills in Male Adolescents with Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is characterized a core triad of symptoms: impaired social interaction, problems with verbal and nonverbal communication, and unusual, repetitive, or severely limited activities and interests (APA, 2000). Impairments in social development, however, have been considered the most salient and handicapping aspect of ASD and, traditionally, the primary deficit from which the diagnosis results. From a cognitive standpoint, it has been argued that these social impairments in individuals with ASDs arise as a result of deficits in Theory of Mind (ToM) development. The degree to which impairment in ToM corresponds to real-world social-communicative impairments has received little attention, however. The purpose of this study was to determine whether ToM and pragmatic language skills discriminated between adolescents with ASD and typically developing, age-matched comparison participants. The study also attempted to explore the relationships between ToM, pragmatic language, and social skills and test the model that pragmatic language mediates the relationship between ToM and social skills. Results indicated that ToM significantly predicted pragmatic language skills and that pragmatic language skills, and not ToM, significantly discriminated between adolescents with ASD (N = 10) and typically developing comparison participants (N = 10). The mediation model above was not supported by regression analysis; however, the results do provide some insight into the relationships between ToM, pragmatic language, and social skills. Implications of these findings, limitations of the study, and recommendations for future research were discussed

Analyzing Repeated Measures Marginal Models on Sample Surveys with Resampling Methods

Packaged statistical software for analyzing categorical, repeated measures marginal models on sample survey data with binary covariates does not appear to be available. Consequently, this report describes a customized SAS program which accomplishes such an analysis on survey data with jackknifed replicate weights for which the primary sampling unit information has been suppressed for respondent confidentiality. First, the program employs the Macro Language and the Output Delivery System (ODS) to estimate the means and covariances of indicator variables for the response variables, taking the design into account. Then, it uses PROC CATMOD and ODS, ignoring the survey design, to obtain the design matrix and hypothesis test specifications. Finally, it enters these results into another run of CATMOD, which performs automated direct input of the survey design specifications and accomplishes the appropriate analysis. This customized SAS program can be employed, with minor editing, to analyze general categorical, repeated measures marginal models on sample surveys with replicate weights. Finally, the results of our analysis accounting for the survey design are compared to the results of two alternate analyses of the same data. This comparison confirms that such alternate analyses, which do not properly account for the design, do not produce useful results.

Electrical Interactions via the Extracellular Potential Near Cell Bodies

Ephaptic interactions between a neuron and axons or dendrites passing by its cell body can be, in principle, more significant than ephaptic interactions among axons in a fiber tract. Extracellular action potentials outside axons are small in amplitude and spatially spread out, while they are larger in amplitude and much more spatially confined near cell bodies. We estimated the extracellular potentials associated with an action potential in a cortical pyramidal cell using standard one-dimensional cable theory and volume conductor theory. Their spatial and temporal pattern reveal much about the location and timing of currents in the cell, especially in combination with a known morphology, and simple experiments could resolve questions about spike initiation. From the extracellular potential we compute the ephaptically induced polarization in a nearby passive cable. The magnitude of this induced voltage can be several mV, does not spread electrotonically, and depends only weakly on the passive properties of the cable. We discuss their possible functional relevance

A review of statistical methods in the analysis of data arising from observer reliability studies (Part II) *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75734/1/j.1467-9574.1975.tb00259.x.pd

Analyzing Repeated Measures Marginal Models on Sample Surveys with Resampling Methods

Packaged statistical software for analyzing categorical, repeated measures marginal models on sample survey data with binary covariates does not appear to be available. Consequently, this report describes a customized SAS program which accomplishes such an analysis on survey data with jackknifed replicate weights for which the primary sampling unit information has been suppressed for respondent confidentiality. First, the program employs the Macro Language and the Output Delivery System (ODS) to estimate the means and covariances of indicator variables for the response variables, taking the design into account. Then, it uses PROC CATMOD and ODS, ignoring the survey design, to obtain the design matrix and hypothesis test specifications. Finally, it enters these results into another run of CATMOD, which performs automated direct input of the survey design specifications and accomplishes the appropriate analysis. This customized SAS program can be employed, with minor editing, to analyze general categorical, repeated measures marginal models on sample surveys with replicate weights. Finally, the results of our analysis accounting for the survey design are compared to the results of two alternate analyses of the same data. This comparison confirms that such alternate analyses, which do not properly account for the design, do not produce useful results

Evidence for a protein tether involved in somatic touch

The gating of ion channels by mechanical force underlies the sense of touch and pain. The mode of gating of mechanosensitive ion channels in vertebrate touch receptors is unknown. Here we show that the presence of a protein link is necessary for the gating of mechanosensitive currents in all low-threshold mechanoreceptors and some nociceptors of the dorsal root ganglia (DRG). Using TEM, we demonstrate that a protein filament with of length ∼100 nm is synthesized by sensory neurons and may link mechanosensitive ion channels in sensory neurons to the extracellular matrix. Brief treatment of sensory neurons with non-specific and site-specific endopeptidases destroys the protein tether and abolishes mechanosensitive currents in sensory neurons without affecting electrical excitability. Protease-sensitive tethers are also required for touch-receptor function in vivo. Thus, unlike the majority of nociceptors, cutaneous mechanoreceptors require a distinct protein tether to transduce mechanical stimuli

Sensitivity analysis for missing outcomes in time-to-event data with covariate adjustment

Covariate-adjusted sensitivity analyses is proposed for missing time-to-event outcomes. The method invokes multiple imputation (MI) for the missing failure times under a variety of specifications regarding the post-withdrawal tendency for having the event of interest. With a clinical trial example, we compared methods of covariance analyses for time-to-event data, i.e., the multivariable Cox proportional hazards model and non-parametric ANCOVA, and then illustrated how to incorporate these methods into the proposed sensitivity analysis for covariate adjustment. The MI methods considered are Kaplan-Meier Multiple Imputation (KMMI), covariate-adjusted and unadjusted proportional hazards multiple imputation (PHMI). The assumptions, statistical issues, and features for these methods are discussed

Preclinical Efficacy of a Carboxylesterase 2-Activated Prodrug of Doxazolidine

Doxazolidine (Doxaz) is a functionally distinct formaldehyde conjugate of doxorubicin (Dox) that induces cancer cell death in Dox-sensitive and resistant cells. Pentyl PABC-Doxaz (PPD) is a prodrug of Doxaz that is activated by carboxylesterase 2 (CES2), which is expressed by liver, non-small cell lung, colon, pancreatic, renal, and thyroid cancer cells. Here, we demonstrate that in two murine models, PPD was effective at slowing tumor growth and demonstrated markedly reduced cardiotoxic and nephrotoxic effects, as well as better tolerance, relative to Dox. Hepatotoxicity, consistent with liver expression of the murine CES2 homolog, was induced by PPD. Unlike irinotecan, a clinical CES2-activated prodrug, PPD produced no visible gastrointestinal damage. Finally, we demonstrate that cellular response to PPD may be predicted with good accuracy using CES2 expression and Doxaz sensitivity, suggesting that these metrics may be useful as clinical biomarkers for sensitivity of a specific tumor to PPD treatment