Universal thermal climate index in the Arctic in an era of climate change: Alaska and Chukotka as a case study.

The modern unambiguous climate change reveals in a rapid increase of air temperature, which is more distinctly expressed in the Arctic than in any other part of the world, affecting people health and well-being. The main objective of the current research is to explore the inter- and intra-annual changes in thermal stress for people in the Arctic, specifically for two parts of Beringia: Alaska, USA, and Chukotka, Russia, using climatology of the universal thermal climate index (UTCI). Data for 39 locations are taken from the ERA5-HEAT reanalysis for the period 1979-2020. Climatologically, the study area is divided into four subregions in Alaska: North, Interior, West and South, and two in Chukotka: Interior and Coast. The extreme coldest UTCI categories (1 and 2) are most common in coastal locations of northern Alaska and Chukotka, where strong winds exacerbate the low temperatures during winter. The results show that the frequency of category 1 (UTCI<-40°C) varies spatially from a quarter of all hours annually in Alaska North to almost zero in Alaska South. On the other hand, the warmest categories are rarely reached almost everywhere in Alaska and Chukotka, and even categories 7 and 8 (UTCI between +26 and +38°C) are found occasionally only at interior locations. Category 6 with no thermal stress (UTCI between +9 and+26°C) has frequencies up to 3% and 25% in Alaska North and Interior, respectively. The extremely cold thermal stress frequencies have substantially decreased over the 1979-2020 period, especially in Alaska North and Chukotka Coast. At the same time, the number of hours with UTCI in the comfortable category of thermal perception has increased depending on subregion, from 25 to 203 h/year. Overall, a decrease in the UTCI categories of extremely cold stress is coupled with an increase in the comfortable range in both Alaska and Chukotka. The salient conclusion is that, from the point of view of comfort and safety, global warming has a positive impact on the climatology of thermal stress in the Arctic, providing advantages for the development of tourism and recreation.

Development of an optical biosensor for the detection of Trypanosoma evansi and Plasmodium berghei.

A laboratory prototype system that correlates murine blood absorbance with degree of infection for Plasmodium berghei and Trypanosoma avensi has been designed, constructed and tested. A population (n = 6) of control uninfected, Plasmodium infected and Trypanosoma infected BALB/c mice were developed and spectral absorption measurements pre and post infection were made every 3 days. A fibre optic spectrometer set-up was used as the basis of a laboratory prototype biosensor that uses the Beer Lambert Law to relate Ultraviolet-Visible-Near-infrared absorbance data to changes in murine blood chemistry post infection. Spectral absorption results indicate a statistically relevant correlation at a 650 nm with infection for Plasmodium from between 4 and 7 sampling days' post infection, in spite of significant standard deviations among the sample populations for control and infected mice. No significant spectral absorption change for Trypanosoma infection was been detected from the current data. Corresponding stained slides of control and infected blood at each sampling date were taken with related infected cell counts determined and these correlate well for Plasmodium absorbance at 650 nm.

Fibre optic spectrophotometry for the in vitro evaluation of ultraviolet radiation (UVR) spectral transmittance of rabbit corneas.

A fibre optic spectrophotometer front-end system for measuring corneas to overcome shortcomings associated with existing instruments was tested. The system allowed prompt measurement postmortem, minimizing beam pathlength to reduce the effects of scatter and unwanted refraction and eliminated optical interfaces and cuvette media. Rabbit corneas were excised immediately postmortem and placed on a detecting fibre optic coupled to an Ocean Optics spectrophotometer and illuminated by a deuterium-halogen source. The compact instrument with its small beam size allowed tissue profiling at test points across the corneal surface and efficient interchange for comparison of different tissues. This simplified system operation allowed rapid tissue altering to study induced changes on transmittance. The corneal transmittance data showed a consistent sharp cut-off at 320 nm in the ultraviolet radiation (UVR) spectrum, which decayed rapidly from postmortem swelling. Inter- and intra-corneal consistency was demonstrated by comparing data from different regions of the same cornea and those from opposite eyes. Changes to the spectra, particularly in the UVB below 300 nm, were evident when the corneal epithelium was removed, indicating that this layer is not the only corneal UVR filter. The new system reduced much of the variability associated with previous methods, as it rapidly measured corneal transmittance postmortem. Data are in broad agreement with published transmittance curves. The removal of the corneal epithelium revealed a substantial stromal contribution to the overall corneal UVR absorption, suggesting that corneas with pathologically or iatrogenically thinned stromas are less effective UVR blockers.

A novel sensor array for field based ocular ultraviolet radiation measurements.

The intensification of terrestrial solar ultraviolet radiation (UVR) due to the diminution of the ozone layer has promoted a variety of research into establishing the impact of this elevated potential dose of UVR on biological tissues. Certain anterior ocular tissues have been found to be susceptible to damage by incident UVR and potentially blinding diseases such as pterygium are thought to be a direct result of absorbed UVR at the nasal limbus. There is a need for more accurate quantification and localisation of incident UVR at the anterior ocular surface. A novel solar blind photodiode sensor array system has been designed, constructed and tested for this purpose. Initial measurements to quantify the irradiance across the anterior ocular surface within the latitudes known as the 'pterygium belt' provide us with a set of core data for different head orientations and tilt angles and indicate the accuracy and stability of the system.

Detection of atmospheric nitrogen dioxide using a miniaturised fibre-optic spectroscopy system and the ambient sunlight.

A miniaturised fibre-optic spectrometer based system is presented for direct detection of one of the major atmospheric pollutants, nitrogen dioxide, by absorption spectroscopy using the ambient sunlight as light source. The detection system consists of a 10 cm collimator assembly, a fibre-optic cable and a portable diode-array spectrometer. The absorbance spectrum of the open-path is calculated using a reference spectrum recorded when the nitrogen dioxide (NO2) concentration in the atmosphere is low. The relative concentration of the pollutant is calculated normalising the detected spectra and subtracting the background broadband spectrum from the specific NO2 absorbance features, since the broadband spectrum changes according to atmospheric conditions and solar intensity. Wavelengths between 400 and 500 nm are used in order to maximise sensitivity and to avoid interference from other species. Calibration is carried out using Tedlar sample bags of known concentration of the pollutant. A commercial differential optical absorption spectroscopy (DOAS) system is used as a reference standard detection system to compare the results with the new system. Results show that detection of NO2 at typical urban atmospheric levels has been achieved using an inexpensive field based fibre-optic spectrometer and a readily available, easy to align, light source. In addition the new system can be used to get a semi-quantitative estimation of the nitrogen dioxide concentration within errors of 20%. While keeping the typical benefits of open-path techniques, the new system has important advantages over them such as cost, simplicity and portability.

A new rapid and simple non-radioactive assay to monitor and determine the proliferation of lymphocytes: an alternative to [3H]thymidine incorporation assay.

A one-step non-radioactive assay to determine the proliferation of murine lymphocytes, lymphoid tumor cells and hybridoma cells is described. This assay requires the addition of Alamar Blue dye to cell cultures and the degree of change in its color, which is reflective of the extent of cellular proliferation, can be determined by an ELISA plate reader. Alamar Blue must be added during the initial phase of cell culture. The pattern of concanavalin A (ConA) or anti-CD3 antibody-induced proliferative response of murine lymphocytes as assessed by Alamar Blue was similar to that of a [3H]thymidine assay. Similarly, the spontaneous proliferation curve of anti-CD3 antibody secreting cell line (YCD3-1), monocytic macrophage cell lines (PU5-1.8, P388D1, J774.1) and myeloma cells (Sp2/0) as determined by Alamar Blue closely resembled that of the [3H]thymidine assay. The minimum detectable number of proliferating cells was comparable in Alamar Blue and [3H]thymidine assays. Since cell lysis/extraction and washing procedures are not involved in the Alamar Blue assay, this approach has several distinct advantages over currently available assays (eg. [3H]thymidine). First, it allows daily monitoring of proliferation without compromising the sterility of cultures. An indication of proliferation can be evaluated (spectrophotometrically or visually) as early as 24 h after ConA stimulation. Second, unlike previously reported assays, Alamar Blue permits further analysis of proliferating cells by other methods. Analysis of cells in culture with Alamar Blue for various surface antigens (CD44, CD45RB, CD4, heat stable antigen) by flow cytometry revealed that the fluorescent profile and relative percentage of cells in cultures with the Alamar Blue were comparable to those without this reagent. The salient advantages of Alamar Blue assay over the [3H]thymidine assay include: (i) non-radioactivity; (ii) simplicity; (iii) less costly; (iv) non-labor intensive; (v) rapidity of assessment of proliferation of large number of samples; (vi) non-toxicity; (vii) usefulness in determining the kinetics of cell growth of hybridomas; and (viii) non-interference of secretion of antibodies by a hybridoma cell line.

Quantification of the ultraviolet radiation (UVR) field in the human eye in vivo using novel instrumentation and the potential benefits of UVR blocking hydrogel contact lens.

BACKGROUND/AIMS: Certain degenerative eye conditions occur predominantly nasally, at the limbal region, and are associated with solar ultraviolet radiation (UVR) induced damage. The relative contribution to the in vivo ocular flux of (a) the reflection of UVR incident on the skin of the nose onto the nasal limbus, and (b) the focusing of UVR incident on the temporal side of the cornea onto the nasal limbus were examined. METHODS: A novel photodiode sensor array was used to measure the UVR field across the eye. In addition, a novel spectrometer set-up was used to measure the spectrum of radiation refracted across the cornea. The efficacy of UVR blocking hydrogel contact lenses in filtering incident UVR was assessed in vivo. RESULTS: Qualitative and quantitative data indicated an increase nasally of UVR. Photodiode readings showed a net UVR increase from the temporal to the nasal side. Transmission curves showed that most UVR incident on the limbal region is either absorbed by, or transmitted through, the ocular tissues. This radiation is filtered by UVR blocking soft contact lens. CONCLUSIONS: An increased UVR flux on the nasal side of the eye, due to reflection off the nasal skin, was identified in vivo. Any UVR passing through the cornea is either absorbed by the conjunctiva and/or transmitted through it onto the sclera where it is absorbed. UVR blocking hydrogel contact lenses can eliminate these sources of UVR.

The British version of the Childhood Health Assessment Questionnaire (CHAQ) and the Child Health Questionnaire (CHQ).

We report herein the results of the cross-cultural adaptation and validation into the British language of the parent's version of two health related quality of life instruments. The Childhood Health Assessment Questionnaire (CHAQ) is a disease specific health instrument that measures functional ability in daily living activities in children with juvenile idiopathic arthritis (JIA). The Child Health Questionnaire (CHQ) is a generic health instrument designed to capture the physical and psychosocial well-being of children independently from the underlying disease. A total of 440 subjects were enrolled: 219 patients with JIA (17% systemic onset, 41% polyarticular onset, 33% extended oligoarticular subtype, and 9% persistent oligoarticular subtype) and 221 healthy children. The CHAQ clinically discriminated between healthy subjects and JIA patients, with the systemic, polyarticular and extended oligoarticular subtypes having a higher degree of disability, pain, and a lower overall well-being when compared to their healthy peers. Also the CHQ clinically discriminated between healthy subjects and JIA patients, with the systemic onset, polyarticular onset and extended oligoarticular subtypes having a lower physical and psychosocial well-being when compared to their healthy peers. In conclusion the British version of the CHAQ-CHQ is a reliable, and valid tool for the functional, physical and psychosocial assessment of children with JIA.

Amplified-spontaneous-emission power oscillation in a beam-wave interaction.

We present in this paper compelling evidence supporting the three-wave traveling-wave theory developed by Pierce fifty years ago. The transition in a Smith-Purcell free-electron laser from low, through moderate amplified spontaneous emission, to strong gain conditions was carefully controlled. Below threshold, the emitted far-infrared power exhibits oscillations with a cubic dependence on the electron beam current. Both characteristics are expected in a three-wave interaction yet, to date, have not been observed.

Microspectrophotometric analysis of respiratory pigments using a novel fibre optic dip probe in microsamples.

A microspectrophotometer system to monitor the reduction of mitochondrial respiratory pigments in cell extracts and permeabilized cells has been developed. The novel optical fibre set-up uses visible spectrophotometry to measure the reduction of mitochondrial electron carriers. The basis of the system is an Ocean Optics S1000 spectrometer, a broadband tungsten based light source, input and output coupling fibre optics and a fibre optic dip-probe which requires less than 20 microl of sample for analysis. The spectral range of the system is from 250 to 850 nm with a spectral resolution of 0.5 nm. Data are presented for the reduction of purified cytochrome c by the reducing agent sodium dithionite and the reduction of cytochrome c by isolated mitochondria using sodium succinate as substrate. Reduction of cytochrome c by digitonin permeabilized cultured mouse cells, C2C12, is also shown. The effect of temperature on cytochrome c reduction in these assays is also demonstrated. The optical design of the probe system is optimized to maintain maximum light throughput and spectral resolution. The key features of the system are small sample size, front-end adaptability, high sensitivity and fast multispectral acquisition which are essential for observing these biological reactions in vivo.

Geometric approach to wavelength tuning of the Cerenkov free-electron laser.

We present a new and greatly simplified derivation of the tuning relation for a Cerenkov free-electron laser. The laser uses an electron beam to excite coherent light in a planar waveguide. The geometric (or zig-zag) theory of waveguides is used to model the set of guided modes, while properties of hte Cerenkov radiation dictate which modes are excited. The results obtained are identical to earlier research based on the formal application of Maxwell's equations. However, the geometric approach adds physical insight into the Cerenkov free-electron laser design problem. The dependence of output wavelength on electron-beam voltage and resonator thickness is plotted. A sample laser is designed for operation from 150 to 825 microm.

Coding potential and regulatory signals of the polyoma virus genome.

The complete DNA sequence of the A2 strain of polyoma virus has been determined. It consists of 5,292 base pairs. The sequence is analysed in terms of its coding potential and sites of possible functional significance or structural interest. The polyoma virus genome is compared with those of related tumour viruses, simian virus 40 and BK virus.

Polyoma virus DNA: Sequence from the late region that specifies the leader sequence for late mRNA and codes for VP2, VP3, and the N-terminus of VP1.

The DNA sequence of part of the late region of the polyoma virus genome is presented. This sequence of 1,348 nucleotide pairs encompasses the leader region for late mRNA and the coding sequence for the two minor capsid proteins VP2 and VP3. The coding sequence for the N-terminus of the major capsid protein overlaps the C-terminus of VP2/VP3 by 32 nucleotide pairs. From the DNA sequence the sizes and sequences of VP2 and VP3 could be predicted. Potential splicing signals for the processing of late mRNA's could be identified. Comparisons are made between the sequence of polyoma virus DNA and corresponding regions of simian virus 40 DNA.

Optimization of Smith-Purcell radiation at very high energies.

A theoretical analysis of Smith-Purcell radiation at very high energies is presented. The energy per unit frequency and solid angle is expressed in closed form as a function of the grating geometry, beam energy, and viewing angles. A certain choice of grating geometry is shown to optimize the output energy for a particular order of radiation. Scaling laws are derived for the energy emitted into all orders of radiation in the relativistic limit. It is shown that the total energy emitted into each order scales as the three-halves power of the beam voltage.

Abnormal technetium labelled white cell scan in the colitis of chronic granulomatous disease.

A child with colitis was treated for Crohn's disease, diagnosed on history, clinical and colonoscopic findings, radiolabelled white cell bowel scan, and colonic histology. After septicaemia caused by an unusual organism, further investigation lead to a diagnosis of chronic granulomatous disease (CGD). The granulomatous colitis of CGD is clinically, histologically, and on white cell scanning, indistinguishable from that in Crohn's disease and should be considered in atypical cases. Infection with unusual 'pseudomonads' should prompt the exclusion of this disorder.

Cancer therapy with localized hyperthermia using an invasive microwave system.

A system has been developed for producing local hyperthermia in small animal tumors by means of an invasive needle microwave antenna. Thermal distributions produced by this system using 1 GHz microwaves have been characterized in mammary adenocarcinomas (MTG-B) implanted in thighs of C3H mice. Therapeutic efficacy by hyperthermia was demonstrated by comparing MTG-B diameters in mice following control, sham or hyperthermia treatment. It is proposed that this system could be employed clinically to provide very local hyperthermia in deep-seated tumors.

An invasive microwave antenna for locally-induced hyperthermia for cancer therapy.

A microwave system has been developed and characterized for delivering heat directly into tumors. This system employs a microwave power source (3-10W) operating in the 500 MHz to 1.3 GHz frequency range, coaxial transmission line, and a monopole antenna. Absorbed power was measured in saline, in tissue equivalent phantoms, and in tumors in live and dead mice. Antennas were designed to operate at 500 MHz and 1 GHz, and the critical design parameters have been identified for this system. Analytical and experimental results obtained in our laboratory suggest that this system is capable of providing controlled temperature distributions appropriate for hyperthermia in animal tumors. Theoretical results predict that 3 GHz may be an optimum choice for this system in animal tumors of approximately 1 cm diameter; the microwave antenna system provides a heat distribution superior to that obtained using a resistance heater of similar dimensions. We propose that further development of this approach may overcome some of the problems associated with other systems which use external radiation sources, and implications for clinical application of this system are discussed.