Drivers of solar radiation variability in the McMurdo Dry Valleys, Antarctica.

Annually averaged solar radiation in the McMurdo Dry Valleys, Antarctica has varied by over 20 W m-2 during the past three decades; however, the drivers of this variability are unknown. Because small differences in radiation are important to water availability and ecosystem functioning in polar deserts, determining the causes are important to predictions of future desert processes. We examine the potential drivers of solar variability and systematically eliminate all but stratospheric sulfur dioxide. We argue that increases in stratospheric sulfur dioxide increase stratospheric aerosol optical depth and decrease solar intensity. Because of the polar location of the McMurdo Dry Valleys (77-78°S) and relatively long solar ray path through the stratosphere, terrestrial solar intensity is sensitive to small differences in stratospheric transmissivity. Important sources of sulfur dioxide include natural (wildfires and volcanic eruptions) and anthropogenic emission.

Difficult Lumbar Puncture: Pitfalls and Tips from the Trenches.

Lumbar puncture has, for many years, been the responsibility of the internal medicine physician or the neurologist. As more patients have undergone spine surgery and with the current increase in body mass index of the general population, the radiologist has been consulted with increasing frequency to perform lumbar puncture with fluoroscopic guidance. Radiology, in fact, is now the dominant overall provider of lumbar puncture procedures. The procedure is more difficult when the needle length increases, and if fluoroscopy is used, landmarks are more difficult to visualize with increasing subcutaneous fat. Our goal with this review was to describe our techniques for lumbar puncture in the difficult patient, with emphasis on using fluoroscopy in the obese patient and to suggest maneuvers that might make the procedure easier. Combining our experience from performing these procedures on an obese population, we would like to share our tips, especially with trainees early in their career.

Detection of an explosive simulant via electrical impedance spectroscopy utilizing the UiO-66-NH2 metal-organic framework.

Electrical impedance spectroscopy, in conjunction with the metal-organic framework (MOF) UiO-66-NH2, is used to detect trace levels of the explosive simulant 2,6-dinitrotoluene. The combination of porosity and functionality of the MOF provides an effective dielectric structure, resulting in changes of impedance magnitude and phase angle. The promising data indicate that MOFs may be used in low-cost, robust explosive detection devices.

Determination of dissolved oxygen in the cryosphere: a comprehensive laboratory and field evaluation of fiber optic sensors.

Recent advances in the Cryospheric Sciences have shown that icy environments are host to consortia of microbial communities, whose function and dynamics are often controlled by the concentrations of dissolved oxygen (DO) in solution. To date, only limited spot determinations of DO have been possible in these environments. They reveal the potential for rates of change that exceed realistic manual sampling rates, highlighting the need to explore methods for the continuous measurement of DO concentrations. We report the first comprehensive field and laboratory performance tests of fiber-optic sensors (PreSens, Regensburg, Germany) for measuring DO in icy ecosystems. A series of laboratory tests performed at low and standard temperatures (-5 to 20 °C) demonstrates high precision (0.3% at 50 µmol/kg and 1.3% at 300 µmol/kg), rapid response times (<20 s), and minimal drift (<0.4%). Survival of freeze thaw was problematic, unless the sensor film was mechanically fixed to the fiber and protected by a stainless steel sheath. Results of two field deployments of sensors to the Swiss Alps and Antarctica largely demonstrate a performance consistent with laboratory tests and superior to traditional methods.

Raman chemical imaging of explosive-contaminated fingerprints.

Raman chemical imaging (RCI) has been used to detect and identify explosives in contaminated fingerprints. Bright-field imaging is used to identify regions of interest within a fingerprint, which can then be examined to determine their chemical composition using RCI and fluorescence imaging. Results are presented where explosives in contaminated fingerprints are identified and their spatial distributions are obtained. Identification of explosives is obtained using Pearson's cosine cross-correlation technique using the characteristic region (500-1850 cm(-1)) of the spectrum. This study shows the ability to identify explosives nondestructively so that the fingerprint remains intact for further biometric analysis. Prospects for forensic examination of contaminated fingerprints are discussed.

CT arteriography and venography in pulsatile tinnitus: preliminary results.

BACKGROUND AND PURPOSE: Pulsatile tinnitus (PT), a common disorder, can be caused by a variety of otologic and vascular lesions. Various imaging modalities, including CT, MR imaging and angiography, and conventional angiography, have been used in the assessment of PT. Ideally, a single imaging study to evaluate for the largest variety of etiologies would be optimal. In our study, we examine the potential for CT arteriography and venography (CTA/V) in the evaluation of PT. METHODS: Sixteen patients with PT were prospectively evaluated by an otolaryngologist, had a normal otologic examination, and were referred for a CTA/V. All examinations were performed on a 16-section multidetector CT. The carotid bifurcations, internal carotid artery course, transverse and sigmoid sinuses, jugular foramen, internal jugular vein, sella turcica, and temporal bones were evaluated. RESULTS: Seven of the 16 patients had lesions on CTA/V that could account for their PT. Examples of pathologic conditions in the series included a significantly dominant venous system, a venous diverticulum with stricture, and a transverse sinus stenosis. CONCLUSIONS: Preliminary findings indicate that CTA/V can be a valuable imaging tool in the assessment of PT. With this technique, arterial, venous, middle, and inner ear causes of PT can be excluded.

Affine versus non-affine deformation in soft biological tissues, measured by the reorientation and stretching of collagen fibres through the thickness of compressed porcine skin.

Skin is a complex three-dimensional structure of cells, collagen fibres and other proteins. However most mechanical analyses treat skin as a two-dimensional membrane, neglecting the through thickness structure. In this paper we investigate through thickness reorientation of collagen fibres. The mode of deformation of skin is also considered. For modelling purposes deformation is usually assumed to be affine. This assumption was tested by constructing a simple geometrical, affine deformation model to predict the through thickness reorientation of collagen fibres, from their initial through thickness angle and the measured deformations of skin samples during compression. The measured reorientation of collagen fibres was found to be very variable, however the average reorientations were consistent with the predictions of the model, with the inclusion of a systematic error. The variation in the reorientation of individual fibres can be explained by the variations in the structure at a micrometre scale. The systematic deviation of reorientations from the model predictions can be explained by a non-affine relationship between the collagen fibres and ground substance at a micrometre scale. However, non-affine deformations at a micrometre scale caused by irregularities of structure are likely to average out at a millimetre scale, because at this level material is evenly distributed.

Visual hallucinations: a prevalence study among hospice inpatients.

The aim of the study was to determine the prevalence of visual hallucinations among hospice inpatients, and the prevalence of a number of possible associated risk factors. One hundred consecutive admissions to St. John's Hospice in Wirral were screened for visual hallucinations in a semi-structured interview. The prevalence of opioid administration, other drugs known to cause hallucinations, brain tumours, liver metastases, bone metastases, lung metastases, known renal failure, eye disease, Alzheimer's disease, Parkinson's disease, other neurodegenerative disorder, psychiatric disorder and epilepsy were also recorded. Subjects were screened for cognitive function using the Folstein mini-mental state examination (MMSE). Survival times from assessment to death were calculated. The results were analysed using arithmetical means with 95% confidence intervals (CI) and odds ratios with 95% confidence intervals. Almost half (47%) the patients had experienced visual hallucinations within the previous month. Hypnagogic or hypnopompic hallucinations of a person standing by the bedside were the commonest type. Median survival time for hallucinators was 15 days (range 0-50 days) and for non-hallucinators was 11 days (range 0-89 days). There was no significant difference in cognitive scores between hallucinators and non-hallucinators. Hallucinations were associated with multiple possible risk factors in every case. Hallucinators were more likely to be taking opioids, although the association was not strong (odds ratio 4.48, 95% CI = 1.6-12.19), and were taking larger numbers of potentially hallucinogenic drugs. It is not clear why some patients on opioids hallucinate and others do not. Data on the prevalence of various possible risk factors yielded ample material for the planning of future studies.

Inactivation of MS-2 phage and poliovirus in groundwater.

Since temperature affects the inactivation rate of viruses in natural water systems, the aim of this study was to determine if a temperature shift could influence the structural integrity of model viruses. When crude lysates of MS-2 phage were seeded into groundwater microcosms and incubated at 27 degrees C, complete virus inactivation took place in eight days. The temperature was then shifted to 4 degrees C. Three days after the temperature shift, a two-log increase in virus titer (reactivation) occurred. However, when purified MS-2 lysates were added to groundwater microcosms, no reactivation was obtained. No reactivation of poliovirus took place when similar microcosm experiments were done. The sedimentation coefficients of MS-2 shifted from 80S to 58S, 48S, 37S, 32S, and 18S as inactivation proceeded in groundwater and distilled water controls. Similarly, the sedimentation coefficients of polioviruses changed from 156S to 142S, 135S, 117S, 105S, 95S, and 80 S as inactivation took place. There was no correlation between % virus inactivation and % decrease in virions with intact sedimentation coefficients, as reported earlier for poliovirus inactivated by chlorine. The results presented support our hypothesis that virus inactivation proceeds gradually, involving the rearrangement and (or) loss of capsomere components that may eventually lead to the ejection of nucleic acids. The intermediate particles generated as inactivation proceeds may be in a reversibly inactivated state, and may revert back to a fully infectious state when chemical components stabilize the virus particle.

Levomepromazine (methotrimeprazine) and the last 48 hours.

Levomepromazine (previously known as methotrimeprazine) has a broad range of beneficial effects in the terminal phase of many illnesses, resulting from its combined antipsychotic, anxiolytic and sedative actions. Levomepromazine can safely be administered in a continuous subcutaneous infusion with most other commonly used drugs in palliative care.

Photooxidative bleaching of chlorophyllin.

Chlorophyllin, a water-soluble, copper-containing porphyrin, can be bleached rapidly in the light or slowly in the dark in a reaction which is oxygen dependent. Both the photo and the dark bleaching reactions are temperature dependent. Cyclic voltammetry measurements show that the copper in the bleached and nonbleached state remains in the +2 redox state and could be readily reduced. This would imply that there is no net oxidative change to the copper during the bleaching process. FT-IR absorption spectroscopy showed vibrations characteristic of a vinyl functionality disappeared upon bleaching. Aqueous solutions of chlorophyllin were not dialyzable through dialysis tubing of molecular weight cut-off, 6000-8000 molecular weight, indicative of an aggregate chlorophyllin micelle. Analysis of products by high performance liquid chromatography showed that the chlorophyllin mixture was more complex than originally anticipated and that two components were lost from the mixture upon photobleaching. One compound that is preferentially lost upon photobleaching has been identified by mass spectral analysis as Cu(II) chlorin e6.

Shedding of enteric coronavirus in adult cattle.

Electron microscopic examination of fecal specimens from adult dairy cows indicated seasonal coronavirus shedding. Fifty-two cows from a 300 cow herd were monitored for shedding of coronavirus. Approximately 50% to 60% of the cows monitored shed coronavirus during the winter months (November to March) of the first year of the study. During 2 subsequent years of monitoring the same cows, 20% to 30% of the cows shed coronavirus during the winter months. Virus shedding was not detected during the summer months (July to September). Half of the cows monitored were vaccinated with a modified-live rotavirus-coronavirus-Escherichia coli combination vaccine; however, vaccination did not influence seasonal shedding of coronavirus, as compared with shedding in the nonvaccinated cows. In nonvaccinated cows that calved in the winter months, the incidence of coronavirus shedding increased from 20% to 30% during the last 2 months of gestation to 65% to 70% at parturition. In vaccinated cows, the incidence of shedding did not increase at parturition.

Treatment of Brucella canis and Brucella abortus in vitro and in vivo by stable plurilamellar vesicle-encapsulated aminoglycosides.

Stable plurilamellar vesicles (SPLVs) entrapping aminoglycosides were used to treat infections due to Brucella species (Brucella canis and Brucella abortus). SPLV-entrapped antibiotics effectively eliminated internalized B. canis in cultures of resident murine peritoneal macrophages and internalized B. abortus in cultures of resident guinea pig peritoneal macrophages. In vivo studies demonstrated that SPLV-entrapped aminoglycosides administered to B. canis-infected mice and B. abortus-infected guinea pigs effectively eliminated bacteria from infected organs. The dosage schedule used involved two intraperitoneal administrations of SPLV-entrapped aminoglycosides at three-day intervals. The results demonstrate the superiority of SPLV-entrapped aminoglycosides to free aminoglycosides in effecting elimination of facultative intracellular bacteria in vitro and in vivo. The use of SPLVs as a drug carrier has broad application to treatment of infections due to other organisms.

Driving with epilepsy: a contemporary perspective.

A committee of concerned neurologists in cooperation with the Tennessee Department of Safety and other agencies reviewed the present state licensing rules for epileptics and offered recommendations for amendments. Epileptics, diabetics, and patients with cerebrovascular disease have an accident rate of approximately twice that of the general population. Seizures probably account for approximately .02% of all vehicle accidents and only .5% to .01% of the fatal accidents. Accidents caused by seizures involve the driver's vehicle alone or an immovable object 80% of the time and occur in less populated and developed areas than controls. The number of seizures within the first three months of therapy is a powerful prognostic indicator. With knowledgeable individual consideration, licensing epileptics to drive could be done much earlier than previously allowed, without affecting road safety. Physicians giving recommendations for licensing in good faith should be protected by law from liability for unforeseen seizure recurrence.

Exogenous progestogen and estrogen implicated in birth defects.

A five-year study of possible teratogenicity of exogenous female sex hormones included three case-control studies and one cohort study. The first case-control study disclosed an estimated relative risk of 8.41 and a highly significant difference in maternal hormonal exposure (P less than .001) between controls and infants with three major anomalies of the VACTERL group (V, vertebral; A, anal; C, cardiac; T, tracheal; E, esophageal; R, renal; and L,limb). Relative risk (RR) estimates of 5.58 (P = .017) and 3.35 (P less than .001) were found in two case-control studies involving maternal hormonal exposure and patients with congenital heart lesions without other malformations. A controlled, single-blind prospective study disclosed an excess of patients with major malformations (RR = 2.75), congenital heart anomalies (RR = 6), and neurological and neural tube disorders preponderant in the presence of a precipitously declining exposure rate during a three-year period in our referral area.