251 research outputs found

    Strategic Review of Tropical Fisheries Management

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    This project addresses the constraints to tropical fisheries development with sustainable exploitation through a strategic assessment of tropical fisheries management with the following purposes: (1) To evaluate relevant research methods for the development of assessment models appropriate to the circumstances of tropical coastal fisheries; and (2) To evaluate the utility of existing strategies for the implementation of management advice. The report consists of three substantive chapters. Chapter 2 contains a detailed socio-economic assessment of various instruments and implementation strategies applicable to tropical capture fisheries. In Chapter 3, a detailed assessment of the fisheries for tropical large marine ecosystems has been conducted using a technique developed by FAO (Granger & Garcia 1996). The data used were the FAO statistics published regularly by FAO. This analysis has been conducted for each of the tropical large marine ecosystems and indicates that there is the potential for increased fishing in a number of these ecosystems. One of the clear requirements identified in Chapter 2 and implicit in Chapter 3, is that there is a significant need for simple and robust fisheries assessment methods which can estimate the potential of a particular resource, its capacity in terms of the level of fishing effort and its current status ie whether it is currently exploited sustainably or not. In Chapter 4, these problems are addressed directly and, using two approaches, significant simplification of fishery methods is developed. In the first approach, simple empirical relationships between the life history parameters of a species are used to develop models of potential yield which can be determined by a simple assessment of fish growth. In the second approach, optimal life history theory is applied to the key demographic parameters of exploited fish populations and using estimates of the Beverton & Holt invariants a significant simplifying of the basic stock assessment equations is developed

    Mapping eutrophication risk from climate change: future phosphorus concentrations in English rivers

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    Climate change is expected to increase eutrophication risk in rivers yet few studies identify the timescale or spatial extent of such impacts. Phosphorus concentration, considered the primary driver of eutrophication risk in English rivers, may increase through reduced dilution particularly if river flows are lower in summer. Detailed models can indicate change in catchment phosphorus concentrations but targeted support for mitigation measures requires a national scale evaluation of risk. In this study, a load apportionment model is used to describe the current relationship between flow and total reactive phosphorus (TRP) at 115 river sites across England. These relationships are used to estimate TRP concentrations for the 2050s under 11 climate change driven scenarios of future river flows and under scenarios of both current and higher levels of sewage treatment. National maps of change indicate a small but inconsistent increase in annual average TRP concentrations with a greater change in summer. Reducing the TRP concentration of final sewage effluent to 0.5 mg/L P for all upstream sewage treatment works was inadequate to meet existing P standards required through the EU Water Framework Directive, indicating that more needs to be done, including efforts to reduce diffuse pollution

    One-Parameter Homothetic Motion in the Hyperbolic Plane and Euler-Savary Formula

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    In \cite{Mul} one-parameter planar motion was first introduced and the relations between absolute, relative, sliding velocities (and accelerations) in the Euclidean plane E2\mathbb{E}^2 were obtained. Moreover, the relations between the Complex velocities one-parameter motion in the Complex plane were provided by \cite{Mul}. One-parameter planar homothetic motion was defined in the Complex plane, \cite{Kur}. In this paper, analogous to homothetic motion in the Complex plane given by \cite{Kur}, one-parameter planar homothetic motion is defined in the Hyperbolic plane. Some characteristic properties about the velocity vectors, the acceleration vectors and the pole curves are given. Moreover, in the case of homothetic scale hh identically equal to 1, the results given in \cite{Yuc} are obtained as a special case. In addition, three hyperbolic planes, of which two are moving and the other one is fixed, are taken into consideration and a canonical relative system for one-parameter planar hyperbolic homothetic motion is defined. Euler-Savary formula, which gives the relationship between the curvatures of trajectory curves, is obtained with the help of this relative system

    Technique for the collection of clear urine from the Nile crocodile (Crocodylus niloticus)

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    Urine samples can be a very useful diagnostic tool for the evaluation of animal health. In this article, a simple technique to collect urine from the Nile crocodile (Crocodylus niloticus) was described, based on a similar unpublished technique developed for the American alligator (Alligator mississippiensis) using a canine urinary catheter. With this technique, it was possible to collect relatively clean urine samples from Nile crocodiles of different sizes using canine urinary catheters or small diameter stomach tubes. Based on the gross anatomical features of the cloaca of the Nile crocodile, it was confirmed that urine accumulates in a chamber consisting of the urodeum and coprodeum. Faecal material is stored temporarily in the very short rectum, which is separated from the urinary chamber by the rectocoprodeal sphincter.The Norwegian Council for Higher Education’s Program for Development, Research and Educationhttp://www.jsava.co.zamn201

    Information Revolutions and the Overthrow of Autocratic Regimes

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    This paper presents a model of information quality and political regime change. If enough citizens act against a regime, it is overthrown. Citizens are imperfectly informed about how hard this will be and the regime can, at a cost, engage in propaganda so that at face-value it seems hard. The citizens are rational and evaluate their information knowing the regime's incentives. The model makes three predictions. First, even rational citizens may not correctly infer the amount of manipulation. Second, as the intrinsic quality of information available becomes sufficiently high, the regime is more likely to survive. Third, the regime benefits from ambiguity about the amount of manipulation, and consequently, as it becomes cheaper to manipulate, the regime is also more likely to survive. Key results of the benchmark static model extend to a simple dynamic setting where there are waves of unrest

    Childbearing intentions in a low fertility context: the case of Romania

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    This paper applies the Theory of Planned Behaviour (TPB) to find out the predictors of fertility intentions in Romania, a low-fertility country. We analyse how attitudes, subjective norms and perceived behavioural control relate to the intention to have a child among childless individuals and one-child parents. Principal axis factor analysis confirms which items proposed by the Generation and Gender Survey (GGS 2005) act as valid and reliable measures of the suggested theoretical socio-psychological factors. Four parity-specific logistic regression models are applied to evaluate the relationship between the socio-psychological factors and childbearing intentions. Social pressure emerges as the most important aspect in fertility decision-making among childless individuals and one-child parents, and positive attitudes towards childbearing are a strong component in planning for a child. This paper also underlines the importance of the region-specific factors when studying childbearing intentions: planning for the second child significantly differs among the development regions, representing the cultural and socio-economic divisions of the Romanian territory

    Profiling of WDR36 Missense Variants in German Patients with Glaucoma

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    PURPOSE. Mutations in WDR36 were recently reported in patients with adult-onset primary open-angle glaucoma (POAG). In this study, the prevalence of WDR36 variants was investigated in patients with glaucoma who were of German descent with diverse age of onset and intraocular pressure levels. METHODS. Recruited were 399 unrelated patients with glaucoma and 376 healthy subjects of comparable age and origin, who had had repeated normal findings in ophthalmic examinations. The frequency of observed variants was obtained by direct sequencing of the entire WDR36 coding region. RESULTS. A total of 44 WDR36 allelic variants were detected, including 14 nonsynonymous amino acid alterations, of which 7 are novel (P31T, Y97C, D126N, T403A, H411Y, H411L, and P487R) and 7 have been reported (L25P, D33E, A163V, H212P, A449T, D658G and I264V). Of these 14 variants, 6 were classified as polymorphisms as they were detected in patients and control individuals at similar frequencies. Eight variants present in 15 patients (3.7%) but only 1 control individual (0.2%) were defined as putative disease-causing variants (P 0.0005). Within this patient group, 12 (80%) presented with high and 3 (20%) with low intraocular pressure. Disease severity and age of onset showed a broad range. CONCLUSIONS. The occurrence of several rare putative diseasecausing variants in patients with glaucoma suggests that WDR36 may be a minor disease-causing gene in glaucoma, at least in the German population. The large variability in WDR36, though, requires functional validation of these variants, once its function is characterized.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

    The post-occipital spinal venous sinus of the Nile crocodile (Crocodylus niloticus) : its anatomy and use for blood sample collection and intravenous infusions

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    The post-occipital sinus of the spinal vein is often used for the collection of blood samples from crocodilians. Although this sampling method has been reported for several crocodilian species, the technique and associated anatomy has not been described in detail in any crocodilian, including the Nile crocodile (Crocodylus niloticus). The anatomy of the cranial neck region was investigated macroscopically, microscopically, radiographically and by means of computed tomography. Latex was injected into the spinal vein and spinal venous sinus of crocodiles to visualise the regional vasculature. The spinal vein ran within the vertebral canal, dorsal to and closely associated with the spinal cord and changed into a venous sinus cranially in the post-occipital region. For blood collection, the spinal venous sinus was accessed through the interarcuate space between the atlas and axis (C1 and C2) by inserting a needle angled just off the perpendicular in the midline through the craniodorsal cervical skin, just cranial to the cranial borders of the first cervical osteoderms. The most convenient method of blood collection was with a syringe and hypodermic needle. In addition, the suitability of the spinal venous sinus for intravenous injections and infusions in live crocodiles was evaluated. The internal diameter of the commercial human epidural catheters used during these investigations was relatively small, resulting in very slow infusion rates. Care should be taken not to puncture the spinal cord or to lacerate the blood vessel wall using this route for blood collection or intravenous infusions.The Norwegian Council for Higher Education’s Programme for Development, Research and Education (NUFU 08/02) and the Royal Netherlands Embassy in South Africa (Prof. Nico Visser).http://www.jsava.co.zaam2014ab201

    Heterozygous Loss-of-Function Variants in CYP1B1 Predispose to Primary Open-Angle Glaucoma

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    Purpose.: Although primary congenital glaucoma (PCG)–associated CYP1B1 mutations in the heterozygous state have been evaluated for association with primary open-angle glaucoma (POAG) in several small studies, their contribution to the occurrence of POAG is still controversial. The present study was conducted to determine whether heterozygous functionally characterized CYP1B1 mutations are associated with the disease in a large cohort of German patients with POAG. Methods.: The frequency of CYP1B1 variants on direct sequencing of the entire coding region was compared in 399 unrelated German patients with POAG (270, POAG; 47, JOAG; and 82, NTG) and 376 control subjects without any signs of glaucoma on ophthalmic examination. In vitro functional assays were performed and relative enzymatic activity of the CYP1B1 variants embedded in their respective background haplotypes and not previously unambiguously classified were determined, to assess their possible causative role. Results.: Apart from known polymorphic variants, 11 amino acid substitutions in CYP1B1 reported before, both in PCG and POAG cases, were identified. After in vitro functional assay, variants P52L and R368H showed marked reduction of activity, confirming their role as loss-of-function mutations similar to previously determined variants G61E, N203S, and G329V. In contrast, variants G168D, A443G, and A465V showed no relevant effects and were thus classified as polymorphisms. Overall, seven functionally impaired variants were present in 13 (3.6%) patients and in 1 (0.2%) control subject (P = 0.002, OR = 5.4). Reanalysis of previous studies reporting CYP1B1 mutations in patients with POAG based on updated functional validation showed a significant excess of carriers among patients compared to controls (OR = 3.85; P = 2.3 × 10−7). Conclusions.: Heterozygous CYP1B1 mutations with absent or reduced relative enzymatic activity can be considered a risk factor for POAG.German Research Foundation/[WE1259/14-3]/DFG/GermanyGerman Research Foundation/[SFB-539]/DFG/GermanyUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM
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