2,480 research outputs found

    Tailward Propagation of Magnetic Energy Density Variations With Respect to Substorm Onset Times

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    t During geomagnetic substorms, around 1015 J of energy is extracted from the solar wind and processed by the Earth’s magnetosphere. Prior to the onset of substorm expansion phases, this energy is thought to be largely stored as an increase in the magnetic field in the magnetotail lobes. However, how, when, and where this energy is stored and released within the magnetotail is unclear. Using data from the Cluster spacecraft and substorm onsets from Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE), we examine the variation in the lobe magnetic energy density with respect to substorm onset for 541 isolated onsets. Based on a cross-correlation analysis and a simple model, we deduce the following: On average, the magnetic energy density increases approximately linearly in the hour preceding onset and decreases at a similar rate after onset. The timing and magnitude of these changes varies with downtail distance, with observations from the mid-tail (X ⪅ −9 RE) showing larger changes in the magnetic energy density that occur ∼ 20 min after changes in the near-tail (X ⪆ −9 RE). The decrease in energy density in the near-tail region is observed before the ground onset identified by SOPHIE, implying that the substorm is driven from the magnetotail and propagates into the ionosphere. The implication of these results is that energy in the near-tail region is released first during the substorm expansion phase, with energy conversion propagating away from the Earth with time

    Rhabdomyolysis and Acute Renal Failure After Fire Ant Bites

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    We describe a 59-year-old patient who developed acute renal failure because of rhabdomyolysis after extensive red fire ant bites. This case illustrates a serious systemic reaction that may occur from fire ant bites. Consistent with the clinical presentation in rhabdomyolysis associated with non-traumatic causes, hyperkalemia, hypophosphatemia, hypocalcemia, and high anion gap acidosis were not observed in this patient. While local allergic reactions to fire ant bites are described in the literature, serious systemic complications with rhabdomyolysis and renal failure have not been previously reported. It is our effort to alert the medical community of the possibility of such a complication that can occur in the victims of fire ant bites

    Single-day therapy: an expert opinion on a recent development for the episodic treatment of recurrent genital herpes

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    One common method for treating recurrent genital herpes outbreaks is 3–5 day episodic therapy with nucleoside analogues. However, since maximum viral replication occurs within 24 h after the onset of symptoms, short-term patient-initiated episodic therapy started at prodromal onset or at the first appearance of lesions in patients without a prodrome may represent an important option. In a recent randomized trial, single-day famciclovir treatment decreased lesion healing time and the duration of pain and other symptoms by approximately 2 days compared to placebo, and prevented progression to a full outbreak in almost one in four patients. Because single-day treatment is more convenient than traditional therapies, it may lead to improved patient compliance and better overall management of recurrent genital herpes outbreaks

    Modulated Instability in Five-Dimensional U(1) Charged AdS Black Hole with R**2-term

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    We study the effect of R**2 term to the modulated instability in the U(1) charged black hole in five-dimensional Anti-de Sitter space-time. We consider the first-order corrections of R**2 term to the background and the linear order perturbations in the equations of motion. From the analysis, we clarify the effect of R**2 term in the modulated instability, and conclude that fluctuations are stable in the whole bulk in the range of values the coefficient of R**2 term can take.Comment: 19 pages, 1 figures; (v4) Published version in JHE

    Development of a minimally invasive microneedle-based sensor for continuous monitoring of β-lactam antibiotic concentrations in vivo

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    Antimicrobial resistance poses a global threat to patient health. Improving the use and effectiveness of antimicrobials is critical in addressing this issue. This includes optimizing the dose of antibiotic delivered to each individual. New sensing approaches that track antimicrobial concentration for each patient in real time could allow individualized drug dosing. This work presents a potentiometric microneedle-based biosensor to detect levels of β-lactam antibiotics in vivo in a healthy human volunteer. The biosensor is coated with a pH-sensitive iridium oxide layer, which detects changes in local pH as a result of β-lactam hydrolysis by β-lactamase immobilized on the electrode surface. Development and optimization of the biosensor coatings are presented, giving a limit of detection of 6.8 μM in 10 mM PBS solution. Biosensors were found to be stable for up to 2 weeks at -20 °C and to withstand sterilization. Sensitivity was retained after application for 6 h in vivo. Proof-of-concept results are presented showing that penicillin concentrations measured using the microneedle-based biosensor track those measured using both discrete blood and microdialysis sampling in vivo. These preliminary results show the potential of this microneedle-based biosensor to provide a minimally invasive means to measure real-time β-lactam concentrations in vivo, representing an important first step toward a closed-loop therapeutic drug monitoring system

    Information transmission in oscillatory neural activity

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    Periodic neural activity not locked to the stimulus or to motor responses is usually ignored. Here, we present new tools for modeling and quantifying the information transmission based on periodic neural activity that occurs with quasi-random phase relative to the stimulus. We propose a model to reproduce characteristic features of oscillatory spike trains, such as histograms of inter-spike intervals and phase locking of spikes to an oscillatory influence. The proposed model is based on an inhomogeneous Gamma process governed by a density function that is a product of the usual stimulus-dependent rate and a quasi-periodic function. Further, we present an analysis method generalizing the direct method (Rieke et al, 1999; Brenner et al, 2000) to assess the information content in such data. We demonstrate these tools on recordings from relay cells in the lateral geniculate nucleus of the cat.Comment: 18 pages, 8 figures, to appear in Biological Cybernetic

    The Eyes Have It: Sex and Sexual Orientation Differences in Pupil Dilation Patterns

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    Recent research suggests profound sex and sexual orientation differences in sexual response. These results, however, are based on measures of genital arousal, which have potential limitations such as volunteer bias and differential measures for the sexes. The present study introduces a measure less affected by these limitations. We assessed the pupil dilation of 325 men and women of various sexual orientations to male and female erotic stimuli. Results supported hypotheses. In general, self-reported sexual orientation corresponded with pupil dilation to men and women. Among men, substantial dilation to both sexes was most common in bisexual-identified men. In contrast, among women, substantial dilation to both sexes was most common in heterosexual-identified women. Possible reasons for these differences are discussed. Because the measure of pupil dilation is less invasive than previous measures of sexual response, it allows for studying diverse age and cultural populations, usually not included in sexuality research
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