Observations of ozone and related species in the northeast Pacific during the PHOBEA campaigns 2. Airborne observations

During late March and April of 1999 the University of Wyoming's King Air research aircraft measured atmospheric concentrations of NO, O3, peroxyacetyl nitrate (PAN), CO, CH4, VOCs, aerosols, and J(NO2) off the west coast of the United States. During 14 flights, measurements were made between 39°-48° N latitude, 125°-129° W longitude, and at altitudes from 0-8 km. These flights were part of the Photochemical Ozone Budget of the Eastern North Pacific Atmosphere (PHOBEA) experiment, which included both ground-based and airborne measurements. Flights were scheduled when meteorological conditions minimized the impact of local pollution sources. The resulting measurements were segregated by air mass source region as indicated by back isentropic trajectory analysis. The chemical composition of marine air masses whose 5-day back isentropic trajectories originated north of 40° N latitude or west of 180° W longitude (WNW) differed significantly from marine air masses whose 5-day back isentropic trajectories originated south of 40° N latitude and east of 180° W longitude (SW). Trajectory and chemical analyses indicated that the majority of all encountered air masses, both WNW and SW, likely originated from the northwestern Pacific and have characteristics of emissions from the East Asian continental region. However, air masses with WNW back trajectories contained higher mixing ratios of NO, NOx, O3, PAN, CO, CH4, various VOC pollution tracers, and aerosol number concentration, compared to those air masses with SW back trajectories. Calculations of air mass age using two separate methods, photochemical and back trajectory, are consistent with transport from the northwestern Pacific in 8-10 days for air masses with WNW back trajectories and 16-20 days for air masses with SW back trajectories. Correlations, trajectory analysis, and comparisons with measurements made in the northwestern Pacific during NASA's Pacific Exploritory Mission-West Phase B (PEM-West B) experiment in 1994 are used to investigate the data. These analyses provide evidence that anthropogenically influenced air masses from the northwestern Pacific affect the overall chemical composition of the northeastern Pacific troposphere. Copyright 2001 by the American Geophysical Union

Evolution of planetary systems with time-dependent stellar mass-loss

Observations indicate that intermediate mass stars, binary stars, and stellar remnants often host planets; a full explanation of these systems requires an understanding of how planetary orbits evolve as their central stars lose mass. Motivated by these dynamical systems, this paper generalizes previous studies of orbital evolution in planetary systems with stellar mass loss, with a focus on two issues: [1] Whereas most previous treatments consider constant mass loss rates, we consider single planet systems where the stellar mass loss rate is time dependent; the mass loss rate can be increasing or decreasing, but the stellar mass is always monotonically decreasing. We show that the qualitative behavior found previously for constant mass loss rates often occurs for this generalized case, and we find general conditions required for the planets to become unbound. However, for some mass loss functions, where the mass loss time scale increases faster than the orbital period, planets become unbound only in the asymptotic limit where the stellar mass vanishes. [2] We consider the chaotic evolution for two planet systems with stellar mass loss. Here we focus on a simple model consisting of analogs of Jupiter, Saturn, and the Sun. By monitoring the divergence of initially similar trajectories through time, we calculate the Lyapunov exponents of the system. This analog solar system is chaotic in the absence of mass loss with Lyapunov time τ0 ≈ 5 Myr; we find that the Lyapunov time decreases with increasing stellar mass loss rate, with a nearly linear relationship between the two time scales. Taken together, results [1] and [2] help provide an explanation for a wide range of dynamical evolution that occurs in solar systems with stellar mass loss. Subject headings: planets and satellites: dynamical evolution and stability — planet-star interactions — stars: evolution — stars: mass loss — white dwarfs – 2 – 1

Reproductive dysfunction and associated pathology in women undergoing military training

Evidence from civilian athletes raises the question of whether reproductive dysfunction may be seen in female soldiers as a result of military training. Such reproductive dysfunction consists of impaired ovulation with or without long term subfertility. We critically review pertinent evidence, which points towards reduced energy availability as the most likely explanation for exercise-induced reproductive dysfunction. Evidence also suggests reproductive dysfunction is mediated by activation of the hypothalamic-pituitary-adrenal axis and suppression of the hypothalamic-pituitary-gonadal axis, with elevated ghrelin and reduced leptin likely to play an important role. The observed reproductive dysfunction exists as part of a female athletic triad, together with osteopenia and disordered eating. If this phenomenon was shown to exist with UK military training this would be of significant concern. We hypothesise that the nature of military training and possibly field exercises may contribute to greater risk of reproductive dysfunction among female military trainees compared with exercising civilian controls. We discuss the features of military training and its participants, such as energy availability, age at recruitment, body phenotype, type of physical training, psychogenic stressors, altered sleep pattern and elemental exposure as contributors to reproductive dysfunction. We identify lines of future research to more fully characterise reproductive dysfunction in military women, and suggest possible interventions which, if indicated, could improve their future wellbeing

Cardiac re-entry dynamics & self-termination in DT-MRI based model of Human Foetal Heart

The effect of heart geometry and anisotropy on cardiac re-entry dynamics and self-termination is studied here in anatomically realistic computer simulations of human foetal heart. 20 weeks of gestational age human foetal heart isotropic and anisotropic anatomy models from diffusion tensor MRI data sets are used in the computer simulations. The fibre orientation angles of the heart were obtained from the DT-MRI primary eigenvalues. In a spatially homogeneous electrophysiological mono domain model with the DT-MRI based heart geometries, we initiate simplified Fitz-Hugh-Nagumo kinetics cardiac re-entry at a prescribed location in a 2D slice, and in the full 3D anatomy model. In a slice of the heart, the MRI based fibre anisotropy changes the re-entry dynamics from pinned to anatomical re-entry. In the full 3D MRI based model, the foetal heart fibre anisotropy changes the re-entry dynamics from a persistent re-entry to the re-entry self-termination

HRT for women with premature ovarian insufficiency: a comprehensive review

BACKGROUND: Premature ovarian insufficiency (POI), often and misleadingly referred to as ‘premature menopause’, is defined as a loss of ovarian activity before the age of 40 years and is characterized by irregular or absent periods and reduced fertility. Symptoms include those associated with the natural menopause (night sweats and vaginal dryness), and with the long-term adverse effects of estrogen deficiency (osteoporosis and cardiovascular disease): the latter is believed to explain the shorter life expectancy associated with POI. OBJECTIVE AND RATIONALE: The objective of the current review was to collect all relevant studies supporting recommendations on the indications, treatment options, and risks of hormone replacement therapy (HRT) (estrogen, progestogens and androgens) for women with POI. SEARCH METHODS: The current review was written based on the best available evidence on the topic collected for the recently published ESHRE guideline on the management of women with POI. PUBMED/MEDLINE and the Cochrane library were searched in a stepwise approach. Relevant references were summarized in evidence tables, with assessment of the quality. OUTCOMES: HRT is strongly recommended for women with POI, mainly for vasomotor and genito-urinary symptom relief. In addition, HRT has been shown to have a role in bone protection and probably also in primary prevention of cardiovascular disease. There is little evidence on the optimal type, regimen and dose of HRT; patient preference for route and method of administration of each component of HRT must be considered when prescribing, as should contraceptive needs. In women with POI, physiological replacement of estrogen (and progesterone) is essential for their health, and the controversies that surround the use of HRT in postmenopausal women do not apply. WIDER IMPLICATIONS: New areas of study on HRT for women with POI should focus on life expectancy, quality of life and neurological function. Furthermore, randomized controlled trials comparing transdermal estradiol with oral estrogens with regard to efficacy, patient satisfaction and side effects are urgently needed. STUDY FUNDING/COMPETING INTERESTS: The authors received no funding for the review. The costs for the development of the ESHRE guideline were covered by ESHRE. The authors have no conflicts of interest to disclose

Correlation between three assay systems for anti-Müllerian hormone (AMH) determination

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VAMPIRE® fundus image analysis algorithms:Validation and diagnostic relevance in hypertensive cats

OBJECTIVES: To validate a retinal imaging software named VAMPIRE® (Vascular Assay and Measurement Platform for Images of the Retina) in feline patients and test the clinical utility in hypertensive cats. ANIMALS STUDIED: One hundred and five healthy cats were enrolled. They represented the normal dataset used in the validation (group 1). Forty-three hypertensive cats with no noticeable retinal abnormalities were enrolled for the clinical validity of the software (group 2). PROCEDURES: Eleven points (4 veins, 4 arteries, and 3 arterial bifurcations) were measured for each digital image. Repeatability and reproducibility of measurements were assessed using two independent operators. Data were statistically analyzed by the Mann-Whiney and Tukey box plot. Significance was considered when P < 0.05. RESULTS: Two hundred and ten retinal images were analyzed for a total of 2310 measurements. Total mean was 9.1 and 6.1 pixels for veins and arteries, respectively. First, second, and third arteriolar bifurcations angles were 73.6°, 76.9°, and 85.4°, respectively. A comparison between groups 1 and 2 showed a statistically significant reduction in arteriolar diameter (mean 3.3 pixels) and branch angle (55°, 47.8° and 59.9°) associated with increasing vein diameter (mean 24.15 pixels). CONCLUSIONS: Current image analysis techniques used in human medicine were investigated in terms of extending their use to veterinary medicine. The VAMPIRE® algorithm proved useful for an objective diagnosis of retinal vasculature changes secondary to systemic hypertension in cats, and could be an additional diagnostic test for feline systemic hypertension

WESTT (Workload, Error, Situational Awareness, Time and Teamwork): An analytical prototyping system for command and control

Modern developments in the use of information technology within command and control allow unprecedented scope for flexibility in the way teams deal with tasks. These developments, together with the increased recognition of the importance of knowledge management within teams present difficulties for the analyst in terms of evaluating the impacts of changes to task composition or team membership. In this paper an approach to this problem is presented that represents team behaviour in terms of three linked networks (representing task, social network structure and knowledge) within the integrative WESTT software tool. In addition, by automating analyses of workload and error based on the same data that generate the networks, WESTT allows the user to engage in the process of rapid and iterative “analytical prototyping”. For purposes of illustration an example of the use of this technique with regard to a simple tactical vignette is presented

Compressibility of titanosilicate melts

The effect of composition on the relaxed adiabatic bulk modulus (K0) of a range of alkali- and alkaline earth-titanosilicate [X 2 n/n+ TiSiO5 (X=Li, Na, K, Rb, Cs, Ca, Sr, Ba)] melts has been investigated. The relaxed bulk moduli of these melts have been measured using ultrasonic interferometric methods at frequencies of 3, 5 and 7 MHz in the temperature range of 950 to 1600°C (0.02 Pa s < s < 5 Pa s). The bulk moduli of these melts decrease with increasing cation size from Li to Cs and Ca to Ba, and with increasing temperature. The bulk moduli of the Li-, Na-, Ca- and Ba-bearing metasilicate melts decrease with the addition of both TiO2 and SiO2 whereas those of the K-, Rb- and Cs-bearing melts increase. Linear fits to the bulk modulus versus volume fraction of TiO2 do not converge to a common compressibility of the TiO2 component, indicating that the structural role of TiO2 in these melts is dependent on the identity of the cation. This proposition is supported by a number of other property data for these and related melt compositions including heat capacity and density, as well as structural inferences from X-ray absorption spectroscopy (XANES). The compositional dependence of the compressibility of the TiO2 component in these melts explains the difficulty incurred in previous attempts to incorporate TiO2 in calculation schemes for melt compressibility. The empirical relationship KV-4/3 for isostructural materials has been used to evaluate the compressibility-related structural changes occurring in these melts. The alkali metasilicate and disilicate melts are isostructural, independent of the cation. The addition of Ti to the metasilicate composition (i.e. X2TiSiO5), however, results in a series of melts which are not isostructural. The alkaline-earth metasilicate and disilicate compositions are not isostructural, but the addition of Ti to the metasilicate compositions (i.e. XTiSiO5) would appear, on the basis of modulus-volume systematics, to result in the melts becoming isostructural with respect to compressibility