Application of electron multiplying CCD technology in space instrumentation

Electron multiplying CCD (EMCCD) technology has found important initial applications in low light surveillance and photon starved scientific instrumentation. This paper discusses the attributes of the EMCCD which make it useful for certain space instruments, particularly those which are photon starved, and explores likely risks from the radiation expected in such instruments

Diagnosis of seeds supply of leafy vegetables in Yaoundé, Cameroon

The traditional leafy vegetables play a major role in the Cameroonian diet. In the metropolitan zone of Yaoundé, these vegetables are produced year round in family and commercial exploitations. The quality of the seeds, their mode of production and their system of distribution are little known. With the aim to better understand the seed system of traditional  vegetables, a study on the supply, the production and the quality of these seeds was carried out. The data were collected using questionnaires on a sample of 133 traditional leafy vegetable producers of the urban and peri-urban zone of Yaoundé. The data were analyzed using SNAP 9  software. The study showed that the most produced species are amaranth (Amaranthus cruentus), nightshade (Solanum scabrum) and jute mallow (Corchorus olitorius). The market-gardeners are influenced in their choice of vegetable to cultivate by the preference of the customers (85.7% of the respondents) and the productivity of the cultivars (66.2% of the  respondents). More than 40% of the respondents buy seeds in the  markets while 7.5% buy seed from other producers and 10.5% in the agricultural inputs stores. About half (47.4%) of the respondents produce seeds by leaving plants in the field after the first or the second harvest while 36.8% of the market-gardeners select the most vigorous plants for seed production. On average, 58.7% of respondents preserve the seeds in hermetically closed bottles and plastic bag. Storage on field is practiced by a significant part of market-gardeners (41.4%). A total of 79.7% of the producers reported constraints with the produced seeds. Poor seed  germination (81.1% of respondents) and the non uniformity of the seed (48.1% of the producers) were reported as the major constraints. The principal source of seed supply in the metropolitan zone of Yaoundé is the self production with rudimentary production and storage techniques subject to many qualitative constraints.Key words: leafy, vegetables, seeds, supply, qualit

Enterprise social network success: Evidences from a multinational corporation

In a globalized world, where companies operate across different locations and work becomes increasingly complex, collaboration in a diversity of ways is required among employees to perform tasks more effectively. Following a case study methodology that involved six interviews across three different country locations, this research addresses the phenomenon of Enterprise Social Networks (ESN) in a multinational corporation with a focus on the assessment of ESN success. The findings show that the company, while trying to assess the success of Yammer, the freemium social networking service at use, has mainly relied on analytics tools to measure usage through indicators such as the total number of users. However, the extent to which ESN is used does not provide a complete picture of ESN success. Business value from that ESN usage is another dimension to be considered to assess success. Therefore, the study of specific ESN usage scenarios that are perceived to have a trackable impact on business results can be used to assess ESN business value on top of ESN usage to fully understand ESN success.COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013info:eu-repo/semantics/publishedVersio

The influence of perfusion solution on renal graft viability assessment

BACKGROUND: Kidneys from donors after cardiac or circulatory death are exposed to extended periods of both warm ischemia and intra-arterial cooling before organ recovery. Marshall’s hypertonic citrate (HOC) and Bretschneider’s histidine-tryptophan-ketoglutarate (HTK) preservation solutions are cheap, low viscosity preservation solutions used clinically for organ flushing. The aim of the present study was to evaluate the effects of these two solutions both on parameters used in clinical practice to assess organ viability prior to transplantation and histological evidence of ischemic injury after reperfusion. METHODS: Rodent kidneys were exposed to post-mortem warm ischemia, extended intra-arterial cooling (IAC) (up to 2 h) with preservation solution and reperfusion with either Krebs-Hensleit or whole blood in a transplant model. Control kidneys were either reperfused directly after retrieval or stored in 0.9% saline. Biochemical, immunological and histological parameters were assessed using glutathione-S-transferase (GST) enzymatic assays, polymerase chain reaction and mitochondrial electron microscopy respectively. Vascular function was assessed by supplementing the Krebs-Hensleit perfusion solution with phenylephrine to stimulate smooth muscle contraction followed by acetylcholine to trigger endothelial dependent relaxation. RESULTS: When compared with kidneys reperfused directly post mortem, 2 h of IAC significantly reduced smooth muscle contractile function, endothelial function and upregulated vascular cellular adhesion molecule type 1 (VCAM-1) independent of the preservation solution. However, GST release, vascular resistance, weight gain and histological mitochondrial injury were dependent on the preservation solution used. CONCLUSIONS: We conclude that initial machine perfusion viability tests, including ischemic vascular resistance and GST, are dependent on the perfusion solution used during in situ cooling. HTK-perfused kidneys will be heavier, have higher GST readings and yet reduced mitochondrial ischemic injury when compared with HOC-perfused kidneys. Clinicians should be aware of this when deciding which kidneys to transplant or discard

A Simplified Method to Distinguish Farmed (Salmo salar) from Wild Salmon: Fatty Acid Ratios Versus Astaxanthin Chiral Isomers

Mislabeling of farmed and wild salmon sold in markets has been reported. Since the fatty acid content of fish may influence human health and thus consumer behavior, a simplified method to identify wild and farmed salmon is necessary. Several studies have demonstrated differences in lipid profiles between farmed and wild salmon but no data exists validating these differences with government-approved methods to accurately identify the origin of these fish. Current methods are both expensive and complicated, using highly specialized equipment not commonly available. Therefore, we developed a testing protocol using gas chromatography (GC), to determine the origin of salmon using fatty acid profiles. We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement. Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples. The method is suitable for wide adaptation because fatty acid methyl ester analysis is a well-established procedure in labs that conduct analysis of lipid composition and food constituents. GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon

Reconstructing ‘the Alcoholic’: Recovering from Alcohol Addiction and the Stigma this Entails

Public perception of alcohol addiction is frequently negative, whilst an important part of recovery is the construction of a positive sense of self. In order to explore how this might be achieved, we investigated how those who self-identify as in recovery from alcohol problems view themselves and their difficulties with alcohol and how they make sense of others’ responses to their addiction. Semi-structured interviews with six individuals who had been in recovery between 5 and 35 years and in contact with Alcoholics Anonymous were analysed using Interpretative Phenomenological Analysis. The participants were acutely aware of stigmatising images of ‘alcoholics’ and described having struggled with a considerable dilemma in accepting this identity themselves. However, to some extent they were able to resist stigma by conceiving of an ‘aware alcoholic self’ which was divorced from their previously unaware self and formed the basis for a new more knowing and valued identity

Incorporation of calcium in glasses: a key to understand the vitrification of sewage sludge

The quantity of sewage sludge generated daily by wastewater treatment plants represents a major environmental problem and a financial burden for plant operators. Valorization strategies focusing on reusing sewage sludge as a raw material are currently developed. Vitrification can help us reduce the volume of waste and binds the components in the structure of chemically stable glasses and glass‐ceramics. In this study, the vitrification of sewage sludge inside a basaltic rock has been simulated by producing glasses and a glass‐ceramic from basalt enriched in calcium that lie between the stability fields of pyroxene and melilite in the system CaO‐MgO‐SiO2‐Al2O3. CaO addition causes the oxidation of the melt at above the liquidus, increases the crystallization temperature, decreases the melting temperature and improves the microhardness of the glasses Glass‐ceramic processes improves the properties of the Ca‐doped basalt glass. The microhardness of the glass (8.2 GPa) and the glass‐ceramic (8.6 GPa) and leaching tests (in the ppb range) place both the glass and the glass‐ceramics at the high end of the mechanical properties and chemical resistance of ceramic tiles for the building industry

The cometary composition of a protoplanetary disk as revealed by complex cyanides

Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface, seeding its early chemistry. Unlike asteroids, comets preserve a nearly pristine record of the Solar Nebula composition. The presence of cyanides in comets, including 0.01% of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can be readily explained by a combination of gas-phase chemistry to form e.g. HCN and an active ice-phase chemistry on grain surfaces that advances complexity[3]. Simple volatiles, including water and HCN, have been detected previously in Solar Nebula analogues - protoplanetary disks around young stars - indicating that they survive disk formation or are reformed in situ. It has been hitherto unclear whether the same holds for more complex organic molecules outside of the Solar Nebula, since recent observations show a dramatic change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks[8]. Here we report the detection of CH3CN (and HCN and HC3N) in the protoplanetary disk around the young star MWC 480. We find abundance ratios of these N-bearing organics in the gas-phase similar to comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of the Solar Nebula was not unique.Comment: Definitive version of the manuscript is published in Nature, 520, 7546, 198, 2015. This is the author's versio

Use of functional feeding strategies to protect Atlantic salmon from virally-induced inflammatory diseases- mechanistic insights revealed by transcriptomic analysis

Over the past few years one of the major concerns in the Atlantic salmon (Salmo salar) farming industry has been the increasing incidence and severity of inflammatory viral diseases. Heart and skeletal muscle inflammation (HSMI) and cardiomyopathy syndrome (CMS) are currently two of the most prevalent viral diseases in commercial Atlantic salmon farms in Norway. Mortality levels in both diseases are generally low but morbidity can be very high with the associated chronic inflammatory response lasting for several months. The consequent reduced growth performance is causing considerable financial impact as HSMI has become increasingly widespread in recent years. The impact of CMS is further exacerbated as it generally affects large fish close to harvest. HSMI lesions occur in the atrium and ventricle in the heart including inflammation and necrosis in epi- endo- and myocardium along with myositis of red skeletal muscle. CMS lesions are commonly observed in the spongy myocardium in the atrium and ventricle of the heart with severe mononuclear inflammation and necrosis. Furthermore, circulatory disturbances associated with reduced cardiac function cause multifocal liver steatosis and necrosis in both diseases. Currently there are no vaccines or any other effective treatments for these diseases and so alternative therapies that could potentially modulate the intensity of the inflammatory response could be crucial to improve the clinical manifestation of the diseases. Therefore, the overall aim of the present study was to evaluate the concept of “clinical nutrition” to improve the clinical symptoms of both viral diseases, HSMI and CMS, through the use of functional feeds formulated with reduced lipid content and increased proportions of anti-inflammatory fatty acids to moderate the apparently uncontrolled inflammatory response in the heart tissue associated with both diseases and also alleviate the secondary hepatic lesions. The experimental work consisted of three major dietary trials in Atlantic salmon in seawater. Two large trials investigated the effects of functional feeds in Atlantic salmon challenged with Atlantic salmon piscine reovirus (ASRV) and piscine myocarditis virus (PMCV), the causal agents of HSMI and CMS, respectively. In both trials, heart transcriptome, heart and liver histopathology and tissue lipid and fatty acid compositions and metabolism were determined post-infection in fish fed with the functional feeds in comparison with fish fed with a standard commercial feed formulation considered as a reference diet. All the functional feeds were formulated to have reduced digestible energy through lower dietary lipid and higher protein contents, and increased levels and proportions of anti-inflammatory long-chain polyunsaturated fatty acids (LC-PUFA), particularly eicosapentaenoic acid (EPA) compared with the reference diets. Histopathology, fatty acid composition and gene expression of heart were assessed over a long time-period of 16 weeks and 14 weeks post-challenge with ASRV and PMCV, respectively. Viral load in heart tissue, hepatic histopathology and fatty acid composition of liver and head kidney along with expression of the genes involved in the eicosanoid and LC-PUFA and eicosanoid biosynthesis pathways were also determined in the HSMI trial. The third trial was a nutritional trial evaluating the effects of dietary digestible energy content on lipid and fatty acid metabolism in salmon fed diets containing graded amounts of lipid. Fatty acid composition of liver and heart were assessed over 12 weeks, along with the hepatic expression of genes of lipid and fatty acid metabolism. The results of this research are presented in four chapters (Chapters 2-5) as four paper manuscripts. The manuscripts/Papers are either published (Chapter 2), in review (Chapter 3 and 4) or drafted for submission (Chapter 5) in appropriate peer-reviewed international journals. Chapter 2 and 3 correspond to the HSMI trial, Chapter 4 to the nutritional trial, and Chapter 5 to the CMS trial. Chapter 2 showed that viral load and histopathology scores were lower in fish fed the functional feeds, especially diet FF1, which displayed better performance. Diet strongly influenced the expression of genes related with the immune and inflammatory responses, with delayed expression in fish fed the functional feeds. Up-regulation of pro-inflammatory genes was correlated with the higher viral load observed at early-mid stages of the disease in fish fed the reference diet (ST). Expression of genes related with the immune response at 16-weeks post challenge reflected the differences in immunomodulation between the functional feeds, with fish fed diet FF1 showing lower expression. Therefore, severity of the heart lesions was correlated with the intensity of the immune response and could be associated with tissue anti-inflammatory LC-PUFA levels. Chapter 3 was focused on liver histopathology, fatty acid composition and LC-PUFA biosynthesis, along with phospholipid fatty acid composition and eicosanoid production in head kidney and heart tissue at early and late stages of ASRV infection. Liver was severely affected by the virus at the beginning of the infection in fish fed the reference ST diet, but the level of lesions were similar in all dietary groups at the end of the trial. Hepatic expression of fatty acyl desaturases was significantly depressed in fish fed the ST diet compare with fish fed the functional feeds despite the lower levels of dietary LC-PUFA in that feed. Thus endogenous production and bioavailability of anti-inflammatory LC-PUFA was potentially enhanced in fish fed the functional feeds. Changes in tissue lipid content, mobilization of fatty acids involved in inflammatory responses and changes in expression of transcription factors and genes involved in eicosanoid biosynthesis were more prominent in head kidney, confirming the important role of this organ in dietary immunomodulation after viral infection. To a lesser extent similar changes were observed in heart tissue, suggesting in situ production of eicosanoids could also be important. The unexpected effects of diet on expression of genes of LC-PUFA biosynthesis were specifically investigated in the trial described in Chapter 4. One aim of this study was to clarify whether dietary lipid content or viral infection was the cause of altered expression of desaturase genes between the different diets. Hepatic expression of other genes of lipid and fatty acid metabolism were also determined to evaluate metabolic changes associated with dietary lipid/energy level. In general, reduction of dietary energy and lipid contents while maintaining similar proportions of dietary fatty acids, led to a general up-regulation of genes involved in lipid biosynthetic pathways. Thus salmon fed lower energy diet showed increased liver expression of fatty acyl desaturases in comparison with fish fed higher energy levels. Heart transcriptomic data in Chapter 5 showed a similar delay in the inflammatory response in fish fed the functional feeds after PCMV infection as observed in the HSMI study. Modulation of inflammatory responses, similar to that previously described after ASRV infection, was also observed in fish fed the functional feeds. However, the differences in the expression of immune related genes and the level of heart lesions were not as prominent at mid-late stages of the disease as in fish fed FF1 in the HSMI trial. The present study demonstrated the beneficial effects of a clinical nutrition approach via functional feeds in two viral inflammatory diseases, HSMI and CMS, currently affecting farmed Atlantic salmon. Dietary immunomodulation increased the availability of anti-inflammatory LC-PUFA and significantly influenced the expression of the genes related with the immune/inflammatory response reducing the level and severity of cardiac and liver lesions and therefore improving the performance of fish suffering the diseases

Gravito-electromagnetic analogies

We reexamine and further develop different gravito-electromagnetic (GEM) analogies found in the literature, and clarify the connection between them. Special emphasis is placed in two exact physical analogies: the analogy based on inertial fields from the so-called "1+3 formalism", and the analogy based on tidal tensors. Both are reformulated, extended and generalized. We write in both formalisms the Maxwell and the full exact Einstein field equations with sources, plus the algebraic Bianchi identities, which are cast as the source-free equations for the gravitational field. New results within each approach are unveiled. The well known analogy between linearized gravity and electromagnetism in Lorentz frames is obtained as a limiting case of the exact ones. The formal analogies between the Maxwell and Weyl tensors are also discussed, and, together with insight from the other approaches, used to physically interpret gravitational radiation. The precise conditions under which a similarity between gravity and electromagnetism occurs are discussed, and we conclude by summarizing the main outcome of each approach.Comment: 60 pages, 2 figures. Improved version (compared to v2) with some re-write, notation improvements and a new figure that match the published version; expanded compared to the published version to include Secs. 2.3 and