Search

The causes of seasonal phytoplankton blooms in the ocean are a debated topic. The disturbance-recovery hypothesis posits that blooms are initiated when seasonally changing light and mixing conditions disrupt attractive equilibrium states in the predator–prey relationship between zooplankton and phytoplankton, leading to an accumulation in phytoplankton biomass. This paper follows up on this notion with a nutrient-phytoplankton-zooplankton (NPZ) model incorporating diffusion and depth-dependent coefficients in which we explore the nature of these attractive states. The reaction–diffusion NPZ model, incorporated with seasonal solar radiation and mixed layer depth data, simulates blooms with better timing than a related ordinary differential equations model but still leaves room for further modeling and improvement. The results of the data-driven, reaction–diffusion model aid in understanding the driving forces of the simulated phytoplankton blooms. The results also reveal a significant influence on the vertical structure of plankton concentration by the attenuation of light with depth in the ocean. Models that accurately simulate blooms tend to share characteristics of the reaction–diffusion model in this paper. The dynamics described in this paper could be a key mechanism that seasonally disrupts the ecological balance between phytoplankton and zooplankton and facilitates a high-latitude marine phytoplankton bloom. [ABSTRACT FROM AUTHOR]

Although the effects of solar radiation, diffusion and mixed layer depths on plankton populations have been studied extensively, it is not intuitive what the equilibrium states of a plankton system should be in the absence of seasonal forcing, nor what are the prime determiners of the attracting equilibrium states. In this study, the linear stability of a nutrient–phytoplankton–zooplankton (NPZ) model in reaction–diffusion form is analyzed to understand how solar radiation, diffusion and mixed layer depth influence the predicted equilibrium states. We incorporate parameters that control the response of the phytoplankton growth rate to solar radiation, control the depth of the upper mixed layer and control the strength of the diffusion. The combined effect of the constant in time parameters for these quantities is shown to significantly influence the stability properties of the NPZ reaction–diffusion model. In our parameter range, we find that diffusion and light are stronger determinants of the equilibrium state than mixed layer depth. This linear stability study gives insight into how these quantities affect the stability states of marine planktonic ecosystems and reinforces the importance of understanding light and upper mixed layer turbulence as important factors in determining the state of the plankton system. [ABSTRACT FROM AUTHOR]

We present an analysis of photometric observations of the eclipsing novalike variable DW UMa made by the CBA consortium between 1999 and 2015. Analysis of 372 new and 260 previously published eclipse timings reveals a 13.6 yr period or quasi-period in the times of minimum light. The seasonal light curves show a complex spectrum of periodic signals: both positive and negative 'superhumps', likely arising from a prograde apsidal precession and a retrograde nodal precession of the accretion disc. These signals appear most prominently and famously as sidebands of the orbital frequency; but the precession frequencies themselves, at 0.40 and 0.22 cycles per day, are also seen directly in the power spectrum. The superhumps are sometimes seen together, and sometimes separately. The depth, width and skew of eclipses are all modulated in phase with both nodal and apsidal precession of the tilted and eccentric accretion disc. The superhumps, or more correctly the precessional motions that produce them, may be essential to understanding the mysterious 'SW Sextantis' syndrome. Disc wobble and eccentricity can both produce Doppler signatures inconsistent with the true dynamical motions in the binary, and disc wobble might boost the mass-transfer rate by enabling the hot white dwarf to directly irradiate the secondary star. [ABSTRACT FROM AUTHOR]

Cherry angiomas (Campbell de Morgan spots) are common acquired red skin papules composed of dilated capillary loops, usually of unknown aetiology. Extragenital lichen sclerosus (LS) presents as porcelain-white scaly atrophic lesions with or without genital involvement. We report two cases of segmental multiple cherry angiomas in association with extragenital LS. Two unrelated women, aged 46 and 66 years, presented with extragenital LS affecting their axillae and lower abdomen. During the examination, both patients were noted to have several hundred red skin papules in a segmental distribution, affecting the left thigh and flank of one woman, and the right abdomen and back of the other. Clinically and histologically, the papules were consistent with cherry angiomas. The striking segmental distribution of multiple cherry angiomas may be due to genetic mosaicism; however, segmental Fabry disease was excluded by sequence analysis of the α-galactosidase A gene. Any causal link between cherry angiomas and LS remains uncertain. [ABSTRACT FROM AUTHOR]

Identifying species boundaries within morphologically indistinguishable cryptic species complexes is often contentious. For the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodoidea: Aleyrodidae), the lack of a clear understanding about the genetic limits of the numerous genetic groups and biotypes so far identified has resulted in a lack of consistency in the application of the terms, the approaches used to apply them and in our understanding of what genetic structure within B. tabaci means. Our response has been to use mitochondrial gene cytochrome oxidase one to consider how to clearly and consistently define genetic separation. Using Bayesian phylogenetic analysis and analysis of sequence pairwise divergence we found a considerably higher number of genetic groups than had been previously determined with two breaks in the distribution, one at 11% and another at 3.5%. At >11% divergence, 11 distinct groups were resolved, whereas at >3.5% divergence 24 groups were identified. Consensus sequences for each of these groups were determined and were shown to be useful in the correct assignment of sequences of unknown origin. The 3.5% divergence bound is consistent with species level separations in other insect taxa and suggests that B. tabaci is a cryptic species composed of at least 24 distinct species. We further show that the placement of Bemesia atriplex (Froggatt) within the B. tabaci in group adds further weight to the argument for species level separation within B. tabaci. This new analysis, which constructs consensus sequences and uses these as a standard against which unknown sequences can be compared, provides for the first time a consistent means of identifying the genetic bounds of each species with a high degree of certainty. [ABSTRACT FROM AUTHOR]

Infantile haemangioma is a common childhood condition, which usually resolves spontaneously and is managed expectantly. In a small percentage of complex cases, haemangiomas may be associated with complications such as persistent bleeding, ulceration, feeding difficulties or visual impairment. Active treatment is often necessary in such cases. Current interventions include surgical, laser and immunomodulatory treatments. Imiquimod 5% cream is a novel alternative topical treatment that may have a potential role in management of these patients. We present our experience of imiquimod 5% cream in the treatment of five children with difficult haemangiomas. We discuss its efficacy and some of the side effects that may be encountered, which have not previously been reported. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To investigate the outcome of limited ileo-caecal resection in children with localised Crohn''s disease (CD) and determine predictors of further surgery. Methods: Review of children diagnosed with CD and operated on for ileo-caecal disease from 1995 to 2005. Age at diagnosis, endoscopic disease distribution, indication for surgery, site of recurrence and date of last follow-up were recorded. Surgery required removal of only the ileo-caecal junction and caecal pole with removal of the minimum terminal ileal length. Results: Thirty seven children underwent intestinal resection. Time between primary operation and most recent follow-up was 3.8 years (range 1 month–8.8 years). Indications for surgery were obstruction/stricture (20), treatment-resistant disease (13) and abscess/perforation peritonitis (4). Follow-up was available in 32. Nine (28%) required re-laparotomy. Median time to second laparotomy was 12 months (range 4–58 months). Eighteen children required no endoscopies after surgery (median follow-up 3.4 years). Conclusion: Most conservative surgery occurs about 2 years after diagnosis. About 1 in 4 children have a further laparotomy within 12 months. Over half of these require division of adhesions. Limited ileo-caecal resection for localized Crohn''s disease is not associated with early peri-anastomotic recurrence. Developments in laparoscopic surgery are likely to further reduce complications from adhesions. [Copyright &y& Elsevier]

We consider model problems for the tear film over multiple blink cycles that utilize a single equation for the tear film; the single non-linear partial differential equation that governs the film thickness arises from lubrication theory. The two models that we consider arise from considering the absence of naturally occurring surfactant and the case when the surfactant is strongly affecting the surface tension. The film is considered on a time-varying domain length with specified film thickness and volume flux at each end; only one end of the domain is moving, which is analogous to the upper eyelid moving with each blink. Realistic lid motion from observed blinks is included in the model with end fluxes specified to more closely match the blink cycle than those previously reported. Numerical computations show quantitative agreement with in vivo tear film thickness measurements under partial blink conditions. A transition between periodic and non-periodic solutions has been estimated as a function of closure fraction and this may be a criterion for what is effectively a full blink according to fluid dynamics. [ABSTRACT FROM AUTHOR]

A survey has been carried out in Leeds, England, in the west Yorkshire industrial heartland, and in neighboring York, surrounded by agriculture, of melanic frequency in the moth species Biston betularia, Odontoptera bidentata, and Apamea crenata. All show a decline in melanics in the postindustrial environment, the first over almost the full range from nearly 100% to less that 10%, the others to smaller extents. Changes in several species over as great a magnitude and as wide an area must result from selection. The results are compared with others along a transect through northern England. The onset of response is progressively later from west to east. The rate of decline is lower at the extremes of the transect to west and east than it is in the center. We still do not have a clear picture of the causes of the changes. One major factor is likely to be selective predation, which is shown to be critically dependent on predation rate. As a consequence, differences in settling behavior between the species could account for different responses even if the species are attacked by the same predators. [ABSTRACT FROM AUTHOR]

Reflects on the experiences of a statistician as head of the Government Statistical Service (GSS) of the National Statistics in Great Britain. Phases of the statistician's first two years at GSS; Code of practice of the National Statistics; National Statistics plan and annual report.

Land molluscs have been collected in the west and south-west coastal regions of Madeira, the main island of the Madeiran archipelago. These are compared with material already reported on from other coastal regions, and from forested areas inland. The inclusion of new data confirms the pattern, previ-ously identified, of low local but high regional diversity. It also demonstrates more conclusively that microgeographical differentiation between site faunas is much more marked in coastal habitats than in the forests inland. At least four coastal regions are discernible in which similar sister species replace each other without obvious ecological divergence. By contrast, the faunal difference between forest and coast is a product of much more profound differentiation, involving different families. [ABSTRACT FROM PUBLISHER]

Background and Methods: Prevailing hypotheses about the causes of ovarian carcinogenesis predict that women with a history of multiple births (twins, triplets, etc.) should be at increased risk of epithelial ovarian cancer. However, the scant available evidence suggests that they may actually be at lower risk. To resolve this issue, we pooled data from eight studies involving 2859 parous women with epithelial ovarian cancer (case patients) and 7434 parous women without ovarian cancer (control women). In addition to assessing their history of multiple births (and the sex of the children, where available), we obtained information on age, parity, oral contraceptive use, and other reproductive factors for each woman. Details of tumor histology were available for all case patients. We estimated the relative risks of various histologic types of ovarian cancers associated with multiple births by using multivariable logistic regression analysis, adjusting for matching and confounding variables.Results: Among these parous women, 73 case patients (2. 6%) and 257 control women (3.5%) had a history of multiple births. The adjusted summary odds ratio (OR) for developing all types of epithelial ovarian cancer that are associated with multiple births was 0.81 (95% confidence interval [CI] = 0.61-1.08). We found no evidence that risks associated with multiple births differed among women with borderline or invasive tumors and among women with same-sex and opposite-sex offspring from multiple births. The risk reductions appeared specific for nonmucinous tumors (n = 2453; summary adjusted OR = 0.71 [95% CI = 0.52-0.98]); in contrast, associations with mucinous tumors (n = 406) were heterogeneous across studies.Conclusions: Parous women with nonmucinous ovarian cancer are no more likely to have a history of multiple births than other parous women, counter to the predictions of current hypotheses for causes of ovarian cancer. [ABSTRACT FROM AUTHOR]

Blau's syndrome refers to the rare familial presentation of a sarcoid-like granulomatous disease classically involving the skin, uveal tract and joints, in the absence of pulmonary manifestations.[sup1] The onset is in childhood, and the mode of inheritance is thought to be autosomal dominant. We report a 15-year-old female and her 22-month-old daughter who presented with clinical features similar to those of Blau's syndrome. In addition to the skin, eye and joint disease, the mother also developed neurological involvement. In both patients long-term systemic corticosteroids were required to control the disease. [ABSTRACT FROM AUTHOR]

Three patients are described with pemphigoid (two with typical adult type and one with juvenile pemphigoid) in whom bullous lesions had clearly been induced by the trauma of scratching. In two patients this phenomenon occurred during the first few weeks of systemic corticosteroid treatment at a time when other lesions were resolving or had completely healed. Although lesions induced by trauma are not usually of great clinical importance, epidermolysis bullosa acquisita may represent a variant of pemphigoid in which trauma-induced lesions predominate. Induction of pemphigoid lesions by trauma may prove a useful method of studying early immunopathological events. [ABSTRACT FROM AUTHOR]

α1-antitrypsin (α1-AT) is a naturally occurring inhibitor of proteinase 3 (PR3) and elastase, two of the target antigens of anti-neutrophil cytoplasmic antibodies (ANCA). An increased incidence of α1-AT phenotypes associated with dysfunctional α1-AT or low serum levels has been reported in patients with anti-PR3 antibodies. We have studied the relationship between ANCA, and phenotypes and serum levels of α1-AT. Phenotypes usually associated with a moderate or severe reduction in α1-AT serum levels or in dysfunctional activity were found more often in individuals with anti-PR3 antibodies than in the general population: four of the 31 patients (13%) with anti-PR3 antibodies had phenotypes MZ (n = 2), S (n = 1) or Z (n = 1) (P < 0.05). However, the corresponding α1-AT serum levels were normal (n = 3) or elevated (n = 1). None of the 31 sera with anti-PR3 antibodies had low levels of α1-AT. No abnormal α1-AT phenotype was demonstrated in seven patients with anti-elastase antibodies, despite a low level of α1-AT in one serum. Anti-myeloperoxidase antibodies are common in patients with ANCA, but no abnormal phenotype or low serum α1-AT level was demonstrated in any of 29 sera containing these antibodies. Finally anti-glomerular basement membrane (GBM) antibodies occur occasionally in patients with ANCA-associated diseases, but again none of 10 sera had an abnormal α1-AT phenotype or low serum level. ANCA were not demonstrated by indirect immunofluorescence in any serum from 73 patients with abnormal α1-AT phenotypes. These results confirm that patients with anti-PR3 antibodies often have α1-AT phenotypes that are usually associated with low serum levels of α1-AT or with dysfunctional protein. Nevertheless, the incidence of anti-PR3 antibodies in patients with abnormal α1-AT phenotypes is very low. This probably reflects the rarity of Wegener's granulomatosis, the major disease associated with anti-PR3 antibodies, and the relative frequency of abnormal α1-AT phenotypes. The mechanism for the development of anti-PR3 antibodies in patients with abnormal α1-AT phenotypes is not clear, but may relate to the increased propensity of unbound and uninhibited PR3 to stimulate autoantibody production. [ABSTRACT FROM AUTHOR]

Background: The diaphragm is usually used with a spermicide. However, some practitioners have suggested that spermicides offer no additional contraceptive protection and have advocated alternative guidelines for the use of diaphragms. The objective of this review was to compare the effectiveness, safety and acceptability of the diaphragm with and without spermicide.Methods and Results: We searched Medline, Embase, Popline, CINAHL, the Cochrane Controlled Trials Register and reference lists of relevant articles. In addition, we contacted experts in the field to identify unpublished studies. Randomized controlled trials comparing women of reproductive age using the diaphragm with and without spermicide as the sole contraceptive method that reported clinical outcomes were selected. Two reviewers independently extracted data on outcomes and trial characteristics and any discrepancies were resolved by consensus or by consultation with the third reviewer. The results of the one identified study are presented descriptively. We identified only one study. No significant difference was found in the pregnancy rates (with typical use or consistent use) or discontinuation rates between the diaphragm-with-spermicide and diaphragm-without-spermicide groups. There was a trend towards higher pregnancy rates in the diaphragm-without-spermicide group. However, this study failed to recruit the planned number of participants and was consequently underpowered.Conclusions: As only one underpowered study was identified, we cannot distinguish between the contraceptive effectiveness of the diaphragm with and without spermicide. We cannot draw any conclusion at this point; further research is needed. [ABSTRACT FROM AUTHOR]

Presents information on the diagnosis of the recurrence of cancer. Description of the research designs that have been used to determine the impact of early detection of recurrence on survival; Examples of screening modalities; Evaluation of the usefulness of screening previously treated and seemingly well cancer patients for tumor markers.

No change in the weal and flare response to histamine was found after placebo and `aggro', the former given double-blind, the latter iii a blind study. Placebo and 'aggro' actions may involve mechanisms other than the final response to mediators of inflammation. The weal and flare response to intradermal histamine is a reproducible and measurable vascular phenomenon and we therefore used it to study the ameliorating action of placebos (which many believe to occur) and to see whether the converse or `aggro' effect could he clicked. [ABSTRACT FROM AUTHOR]

The article focuses on the rediscovery of Discus gueronianus from two sites on hillsides facing the ocean at the western end of Madeira. The locations are highly disturbed but have rich faunas. Endemic species have limited distributions partly because they require specific habitats of small extent. Members of the genus Leiostyla are presented in the laurel forest but are sporadic. The theory that there could be a negative relation between competitive and dispersive ability that would maintain diversity is explained.