Hybrid wind-solar energy resources mapping in the European Atlantic

The complementarity of offshore wind and solar resources can enhance the energy output of a hybrid farm and reduce its variability relative to a stand-alone, conventional offshore wind farm. In this work offshore wind and solar resources are characterised and mapped in a large study area covering the European Atlantic, the North and Baltic Seas, and the Canary Islands. The intra-annual and overall variabilities of wind power density and solar irradiance are investigated, and their complementarity is evaluated on the basis of their correlation. Negatively correlated regions include the seas around Ireland and Great Britain, with vast wind resources (mean wind power density ~1500 Wm-2 off W Ireland) and comparatively limited solar resources (mean solar irradiance ~100 Wm-2). Positively correlated regions include notably the Canary Islands, with the highest values of solar irradiance in the study area (mean values of ~280 Wm-2). Two study sites are chosen for more detailed investigation - one with a negative correlation, off W Ireland; the other with a positive correlation, off the Canary Islands. Even in the positively correlated regions, it is found that the correlation coefficient is never large (always under 0.2), which signals an opportunity for reducing power output variability through hybrid or co-located wind-solar farms. This, along with the other advantages of hybrid or co-located wind-solar farms (optimised use of scarce marine space, shared electrical infrastructure, shared O&M crews and vessels, etc.), attests to their potential in the European Atlantic. This potential could be realised through new hybrid or co-located wind-solar farms, or by retrofitting floating solar PV into existing offshore wind farms.

Techno-economic assessment of potential zones for offshore wind energy: A methodology

This work presents a methodology for the techno-economic assessment and comparison of potential zones for the development of offshore wind energy. The methodology is illustrated through a case study in North Spain, using the high-potential zones designated by the Spanish government. The main elements considered include the bathymetry (water depths), energy production and total working hours based on the wind climate, maintenance windows based on the wave climate, and distance to selected port facilities that can accommodate the installation and operational and maintenance phases of an offshore wind farm. An interesting dichotomy arises moving from west to east along N Spain - energy production and working hours decrease, but maintenance windows increase. Given that both aspects play a role in the costs of an offshore wind project, pondering them adequately is crucial, and the selection of a particular zone for development may depend on project-specific cost models. Water depths may preclude the installation of bottom-fixed structures in certain areas; importantly, they may also represent a constraint for the deployment of certain floating concepts, particularly in the high-potential zones of the Cantabrian Sea. Finally, ports capable of servicing the offshore wind farms are identified and distances to all high-potential zones, calculated. By examining the unique properties of the high-potential zones, this methodology, which can be applied to other regions of interest for offshore wind, provides valuable insights into the advantages and challenges of offshore wind development at each site and thereby contributes to informed decision-making.

Impacts of climate change on wind energy potential in Australasia and South-East Asia following the Shared Socioeconomic Pathways

Wind energy is poised to play a major role in the energy transition. Fluctuations in global atmospheric circulation are expected as a result of climate change, and wind projections based on the most up-to-date scenarios of climate change, the Shared Socioeconomic Pathways (SSPs), anticipate significant changes in wind energy potential in many regions; so far, these changes have not been studied in Southeastern Asia and Australasia, a region with notable wind energy potential. This work investigates the evolution of wind power density and its temporal variability considering the latest scenarios of climate change, the SSPs. More specifically, two scenarios are considered, SSP2-4.5 and SSP5-8.5, corresponding to moderate and high emissions, respectively. As many as 18 global climate models are considered and compared against past-present data, and those that perform best are retained to build a large multi-model ensemble. The results show that projected changes in mean wind power density at the end of the 21st century are of little significance (typically below 5 %); nevertheless, this value can be far surpassed locally. In certain areas (e.g., Vietnam, Borneo) and seasons, remarkable changes in wind power density (exceeding 150 %) are anticipated. Typically, mean values and temporal variability changes are greater in the high-emissions scenario, however, seasonal variability is projected to be more pronounced in the moderate-emissions scenario. These effects of climate change on wind energy potential must be taken into account in the development of wind power in the region, for they will affect the energy production and, therefore, the economic viability of wind farms - not least in those areas where drastic changes are projected.

Testicle histology of the Epicrates cenchria: a morphological and reproductive biology analysis

ABSTRACT The lack of information about anatomy, physiology and reproductive biology in many snake species makes the understanding of these free-living animals’ reproduction and reproductive biotechnics application in captivity difficult. The present study aims to evaluate the Epicrates cenchria’s testicle morphology and correlate these findings with environmental aspects and reproductive biology. The testicles of five specimens of E. cenchria were histologically evaluated, and it was possible to observe seasonality in sperm production, with the presence of mature spermatozoa in the wettest and warmest periods of the year, as well as the highest testicular volume in these periods. Correlating these findings with that reported in the literature on copulation period presupposes a prenuptial (or associated) pattern in E. cenchria.

Climate change impacts on wind energy resources in North America based on the CMIP6 projections

The mid- and long-term evolution of wind energy resources in North America is investigated by means of a multi-model ensemble selected from 18 global climate models. The most recent scenarios of greenhouse gases emissions and land use, the Shared Socioeconomic Pathways (SSPs), are considered - more specifically, the SSP5-8.5 (intensive emissions) and SSP2-4.5 (moderate emissions). In both scenarios, onshore wind power density in the US and Canada is predicted to drop. Under SSP5-8.5, the reduction is of the order of 15% overall, reaching as much as 40% in certain northern regions - Quebec and Nunavut in Canada and Alaska in the US. Conversely, significant increases in wind power density are predicted in Hudson Bay (up to 25%), Texas and northern Mexico (up to 15%), southern Mexico and Central America (up to 30%). As for the intra-annual variability, it is poised to rise drastically, with monthly average wind power densities increasing up to 120% in certain months and decreasing up to 60% in others. These changes in both the mean value and the intra-annual variability of wind power density are of consequence for the Levelised Cost of Energy from wind, the planning of future investments and, more generally, the contribution of wind to the energy mix.

Coleta de sêmen em Leopardus guttulus pelo método do cateterismo uretral

RESUMO Considerando a realidade conservacionista dos animais mantidos em cativeiro, em especial os pequenos felídeos silvestres, objetivou-se, com este estudo, descrever o método de coleta de sêmen por cateterismo uretral em Leopardus guttulus cativos, anestesiados com cetamina-dexmedetomidina. Inicialmente foram utilizados 13 animais para coleta de sêmen por cateterismo mediante o uso de diferentes doses de cetamina-dexmedetomidina. Após determinação da dose anestésica ideal para coleta de sêmen nessa espécie, cinco L. guttulus machos foram submetidos a coletas seriadas de sêmen pelo método do cateterismo. A dose ideal para coleta de sêmen foi de 0,008mg/kg de dexmedetomidina e 10mg/kg de cetamina. Os valores médios para volume e concentração foram de 35,9µL e 552,8x106sptz/mL. Com média de 71% de motilidade e 3,1 de vigor, 68% dos espermatozoides apresentaram vitalidade (integridade de membrana) e 77% integridade acrossomal. Sobre as patologias espermáticas, obteve-se uma média de 28% de espermatozoides com defeitos maiores, 6% com defeitos menores e 67% normais. As vantagens do método, como a facilidade e o baixo custo, fazem recomendar sua utilização em L. guttulus, pois foram apresentados bons resultados quanto à concentração espermática, à motilidade, ao vigor, à viabilidade espermática e à integridade acrossomal, sendo uma técnica promissora para utilização em felinos selvagens.

Aspectos da biologia reprodutiva de Boa constrictor constrictor: um estudo histológico dos testículos nos períodos reprodutivos de quiescência e máxima atividade

RESUMO As serpentes pertencem ao segundo maior grupo dentro dos répteis, podendo apresentar sazonalidade quanto à espermatogênese, com produção descontínua ou contínua. O presente trabalho tem como objetivo caracterizar aspectos da biologia reprodutiva de Boa constrictor constrictor com base nos achados histológicos dos testículos nos períodos de máxima atividade (período de gametogênese) e quiescência. Os testículos de dois espécimes de Boa c. constrictor (7767 e 11752) foram cortados a uma espessura de 3μm em micrótomo, corados com azul de toluidina 1%, fotodocumentados e descritos. A presença de espermatozoides na luz do túbulo seminífero no indivíduo 7767 indica um período de máxima gametogênese, enquanto o lúmen dos túbulos seminíferos pouco evidentes, sem a presença de espermatozoides e de células gaméticas em divisão, caracteriza o indivíduo 11752 em período quiescente. Mediante os achados histológicos descritos no presente estudo, concluiu-se que Boa c. constrictor apresenta sazonalidade em relação à gametogênese, sendo esse padrão de sazonalidade associado ao período de cópulas relatado em literatura característico de serpentes com padrão pré-nupcial.

Leiomioma vulvar em lobo-guará (Chrysocyon brachyurus) - relato de caso

RESUMO Descrição de leiomioma vulvar em lobo-guará (Chrysocyon brachyurus), fêmea, castrada, apresentando 10 anos de idade e mantida em cativeiro. Com base na avaliação clínica, no monitoramento de formação nodular de crescimento lento e progressivo e no diagnóstico preliminar sugestivo de neoplasia, procedeu-se à exérese da massa tumoral e à identificação anatomopatológica do leiomioma. Exames complementares radiográficos e ultrassonográficos não apontaram presença de metástases. A ressecção cirúrgica se mostrou satisfatória como conduta clínica, não havendo recidiva.

Sexagem em tamanduá-bandeira (Myrmecophaga tridactyla) por meio do teste da reação em cadeia da polimerase

RESUMO Em tamanduá-bandeira (Myrmecophaga tridactyla) não há dimorfismo sexual, tornando-se necessária a diferenciação entre machos e fêmeas, em especial naqueles indivíduos com finalidade reprodutiva. Entre as diversas técnicas empregadas para a caracterização sexual, a reação em cadeia da polimerase (PCR) é utilizada em mamíferos para identificar uma sequência genética especifica do cromossomo Y (SRY), sendo considerado um meio moderno e eficaz de determinação sexual. O objetivo deste trabalho é padronizar um protocolo para determinação sexual de tamanduá-bandeira por meio da técnica de PCR, utilizando material genético extraído do bulbo capilar desses animais. Mediante esse protocolo, foi possível determinar o sexo de sete animais testados, sendo compatível com o sexo de cada indivíduo. Conclui-se que o protocolo padronizado apresentou total eficácia, sendo possível determinar o sexo de tamanduás-bandeira utilizando material genético extraído do bulbo capilar.

Diagnóstico ecocardiográfico e tratamento de cardiomiopatia dilatada em tamanduá- bandeira ( Myrmecophaga trydactila ) mantido em cativeiro: relato de caso

RESUMO A cardiomiopatia dilatada é uma doença de caráter crônico, que compromete a função cardíaca, resultando em desequilíbrio da circulação sanguínea e da homeostase corporal do animal. Este relato apresenta a evolução do quadro clínico e o tratamento de cardiomiopatia dilatada em um exemplar cativo de tamanduá-bandeira. O animal apresentou quadro clínico de insuficiência cardíaca e foi submetido a duas baterias de exames laboratoriais e de imagem em um período de três meses. Posteriormente, foi iniciado o tratamento com pimobendan e suplementação de taurina, resultando em resposta positiva e melhora dos sinais clínicos do paciente. Os achados ecocardiográficos do caso foram compatíveis com cardiomiopatia dilatada com sinais evidentes de diminuição progressiva das frações de ejeção, bem como encurtamento e aumento expressivo das câmaras cardíacas, quando se comparou este caso ao de cães de grande porte e animais saudáveis da mesma espécie. O tratamento com inotrópico positivo, suplementação dietética de taurina e diuréticos se mostrou eficiente em controlar os sinais clínicos do animal.

Detecção molecular de Neospora caninum em macaco-da-noite (Aotus azarae) de vida livre no estado do Mato Grosso: relato de caso

RESUMO Estudos indicam, por meio de infecção experimental, que primatas não humanos são susceptíveis à infecção por Neospora caninum. Relata-se um caso de um macaco-da-noite (Aotus azarae infulatus), que apresentou sinais inespecíficos e não respondeu à terapêutica clínica de suporte, evoluindo a óbito, encaminhado em seguida para exame anatomopatológico. Amostras de tecidos foram coletadas e processadas rotineiramente para confecção de lâminas histológicas. Microscopicamente, a principal lesão foi observada no coração e consistia em miocardite necrótica multifocal por protozoário, com a presença de estruturas compatíveis com o estágio de taquizoítos de protozoários dos gêneros Neospora sp. ou Toxoplasma sp. No sistema nervoso central, predominantemente no tronco encefálico, havia estruturas semelhantes às descritas no coração. Os resultados da reação em cadeia pela polimerase (PCR) foram positivos para N. caninum e negativos para Toxoplasma gondii, usando DNA extraído do sangue e dos tecidos. Este relato de caso fornece evidências histológicas e moleculares de que o primata em questão foi susceptível a uma infecção natural, porém estudos devem ser realizados para investigar o real papel dos primatas no ciclo de vida de N. caninum.

Multiionic effects on the capacitance of porous electrodes

The rapid and reversible ionic electrosorption in the electrical double layers (EDLs) of moderately charged micropores in contact with a solution is the main concept underlying capacitive energy and desalination devices. For the usual operating conditions, the ion concentration is large enough for the confinement of ions to play an important role in their distribution in the EDL. On the other hand, although most laboratory experiments have been carried out with simple salt solutions, realistic applications require a proper analysis of the effect of the different ionic species existing in natural waters. Here we focus on the role of multiionic solutions on the double layer structure. For this purpose, a model is presented in which the EDL overlap and the existence of a Stern layer are considered. It is also taken into account that the ions can be tightly packed by using the Carnahan-Starling model. This model is applied to analyze the structure of the EDL with multiionic solutions containing divalent ions. The predictions of this model are found to largely differ from those of the better known Bikerman equation, and are more realistic. It is demonstrated that the presence of tiny amounts of divalent ions in the bulk is enough to dominate the EDL behavior, and hence, its capacitance, energy storage, and desalination properties.

Polyelectrolyte-coated carbons used in the generation of blue energy from salinity differences

Polyelectrolyte-coated carbon films are used as electrodes for energy extraction from salinity exchange.

Floating boom performance under waves and currents

Floating booms constitute a fundamental tool for the protection of marine and coastal ecosystems against accidental oil spills. Their containment performances in exposed areas are often impaired by the action of waves, currents and winds in a manner which is dependent on the boom's response as a floating body, and which is not fully understood at present. In this work the relationship between the design parameters of a floating boom section and its efficiency against the mode of failure by drainage under a variety of wave and current combinations is investigated by means of physical modelling. Seven boom models with different geometries and buoyancy-weight ratios are tested with an experimental setup that allows them to have and rotate freely. The model displacements under waves (both regular and irregular) and currents, as well as those of the free surface adjacent to the model, are measured with a Computer Vision system developed ad hoc. Two efficiency parameters are defined-the significant and minimum effective boom drafts-and applied to the results of an experimental campaign involving 315 laboratory tests. Thus, the manner in which the design parameters influence the boom's efficiency under different wave and current conditions is established.

Microbiology of pediatric primary pulmonary tuberculosis

OBJECTIVE

To determine the sensitivity of bacteriologic studies in pediatric pulmonary tuberculosis.

PATIENTS AND METHODS

Between January 1988 and December 1996, 104 consecutive patients aged 0 to 18 years received a diagnosis of primary pulmonary tuberculosis at our institution. Demographic, clinical, laboratory, and bacteriologic data were collected. Clinical specimens were studied for acid-fast bacilli detection by Ziehl-Neelsen stain and cultured for Mycobacterium recovery by Lowenstein-Jensen culture medium. Statistical analysis was performed utilizing chi(2), t tests, and multivariate logistic regression analysis.

RESULTS

Bacteriologic results were available for 57 patients (54.8%). A positive smear or culture result for Mycobacterium tuberculosis was obtained in 9 of 54 patients (16.6%) and 25 of 50 patients (50%), respectively. Confirmation of M tuberculosis disease was achieved in 28 patients (49.1%). Ziehl-Neelsen stain and Lowenstein-Jensen culture recovery rates were 10.3% (14 of 135) and 52% (48 of 92) of specimens studied, respectively. Sputum, pleural fluid, and biopsy material cultures yielded M tuberculosis in 55%, 75%, and 63% of patients, respectively. Mean +/- SD age (13.7 +/- 4.5 years vs 9.6 +/- 4.5 years) and number of samples submitted for culture (1.93 +/- 0.94 vs 1.31 +/- 0.97) were significantly higher in the confirmed tuberculosis disease group (p < 0.05). The presence of a pleural effusion was also more commonly found in the confirmed tuberculosis disease group (p < 0.05).

CONCLUSION

The sensitivity of bacteriologic studies in pediatric pulmonary tuberculosis disease was 49.1%. Age is the main factor associated with the positivity of culture results.

Left atrial calcification in a hemodialysis patient with cor triatriatum

Myocardial calcification is a rare manifestation of abnormal calcium metabolism seen in some patients with chronic renal failure. This report describes the transesophageal echocardiographic and spiral computed tomography (CT) findings in a young hemodialysis female with severe secondary hyperparathyroidism. These findings included calcification of the multiperforated membrane of a cor triatriatum and the wall of the left atrium.

Thromboxane synthetase inhibition and thromboxane receptor blockade preserve pulmonary and circulatory function in a porcine burn sepsis model

BACKGROUND

Thromboxane A2 (TxA2) is a key mediator in the pathophysiology of severe burns and sepsis. This study was performed to assess the potential benefits of TxA2 synthetase inhibition and TxA2 receptor blockade in sepsis after severe thermal injury.

STUDY DESIGN

Pigs with left atrial, aortic, and pulmonary artery catheters received a 40 percent third-degree burn and, 24 hours later, 100 micrograms per kg Escherichia coli endotoxin. The antagonist treatment (BM) group was treated with the TxA2 receptor antagonist BM 13.177, the synthetase treatment (OKY) group with the TxA2 synthetase inhibitor OKY-046, and the control group received saline solution placebo. Another group without burn or endotoxin was used to assess the side effects of BM 13.177.

RESULTS

Both drugs significantly attenuated the changes in pulmonary vascular resistance index, cardiac index, arterial PO2, shunt, oxygen delivery, and oxygen consumption seen after endotoxin. However, cardiac index was significantly decreased in group BM before endotoxin. In healthy pigs, BM 13.177 decreased cardiac index and oxygen delivery and increased the pulmonary vascular resistance index.

CONCLUSIONS

TxA2 synthetase inhibitors and TxA2 receptor blockers are potentially useful in sepsis after severe burns. Comparison between drugs was complicated by the adverse effects of the antagonist, and further investigation with other antagonists is needed.

[The treatment of Paget's disease of bone with second-generation bisphosphonates via intravenous infusion]

We compared the biochemical effects and safety of pamidronate (30 mg a day for 3 consecutive days) versus clodronate (300 mg a day for 3 consecutive days) via intravenous infusion in 14 patients with Paget's disease of bone (PDB). Both drugs induced a decrease in serum alkaline phosphatase levels as well as the elimination of hydroxyproline from urine, an effect most marked in the group treated with pamidronate. The response was maintained for 6 months after the infusion in the majority of the patients. No relevant side effects were found, except post-infusion febricula and in one patient, self-limiting thrombopenia 6 months after the infusion. We conclude that the intravenous infusion of either of the two drugs may constitute a safe and effective alternative for treatment of PDB with marked biochemical activity or resistant to conventional therapy.

Effects of pseudorabies virus infection upon cytotoxicity and antiviral activities of porcine alveolar macrophages

Alveolar macrophages (AM) infected with Pseudorabies virus (PRV) were compared to noninfected AM for cytotoxicity against foreign or transformed cells and production of interferon (IFN). Five PRV strains were used to infect AM including strains that are known to be highly virulent for pigs, i.e. strain 4892 and strain S-62 as well as strains that are regarded as mild or nonvirulent, i.e. BUK and Bartha. The multiplicity of infection ranged from 0.005 to 0.05 TCID50/cell. The target cells in the cytotoxicity assays were either chicken red blood cells, PRV-infected vero cells, or human myeloblastoma cells (K562 cell line). For the production of IFN, AM cultures were treated with polyinosinic:polycytidylic acid (Poly I:C) diluted in tissue culture media at a concentration of 5 micrograms/10(6) cells. Culture supernatants were collected at various times poststimulation and tested for antiviral activity using the Vesicular Stomatitis Virus replication inhibition test. Swine AM were able to lyse chicken red blood cells in an antibody-independent way but not in an antibody-dependent way, whereas lysis of PRV-infected vero cells was accomplished both ways. The cytotoxicity against chicken red blood cells was reduced in the PRV-infected AM as compared to noninfected cells, particularly in AM infected with virulent PRV strains. Specific 51Cr release values for AM infected with S-62 and 4892 strains were 14 and 19, while the noninfected AM had values of 36. Similarly, in the antibody-dependent cytotoxicity assay against PRV-infected vero cells there was no activity of AM against K562 cells. The production of IFN was readily stimulated with Poly I:C. The optimal time for supernatant collection was between 12 and 16 h poststimulation. The antiviral activity was abrogated by treatment of the supernatant with antiserum against human leukocyte IFN; it was therefore considered to be due to interferon-alpha (IFN alpha) released from the macrophages. The antiviral activity present in supernatants of PRV-infected AM was reduced compared to noninfected AM. The difference between AM cultures infected with virulent strains of PRV and noninfected AM cultures was statistically significant at P < or = 0.025. The results provide support to the premise that the role of AM in lung defense can be compromised by PRV infection.

Antibodies to Aujeszky's disease virus in pigs immunized with purified virus glycoproteins

Antibodies to Aujeszky's disease virus (ADV) glycoproteins gII, gIII, and gp50 were compared using four in vitro tests. Antibodies generated by vaccination with a modified-live vaccine (MLV) were also compared. The serological assays employed were: serum neutralization test (SNT), complement facilitated serum neutralization test (C'SNT), complement-mediated cytolysis and antibody dependent cellular cytotoxicity (ADCC). Pigs were immunized with single glycoproteins twice 14 days apart, or once with the modified-live vaccine. Fourteen days after the second immunization, sera were collected. Virus neutralizing activity (SNT) was demonstrated in the sera from all pigs immunized with gp50 and in one out of three immunized with gIII. Sera from the MLV group all had neutralization titers higher than animals immunized with single glycoproteins. Addition of guinea pig complement to the serum neutralization test (i.e., C'SNT) produced an enhancement of antibody titers in all groups except the pigs immunized with gIII. The complement-mediated cytolysis test rendered antibody titers similar in magnitude for all pigs immunized with single glycoproteins, but slightly lower than values for MLV vaccinated pigs. ADCC activity was clearly displayed in sera from pigs immunized with gIII or vaccinated with MLV, whereas sera from pigs immunized with gII or gp50 had a minimal response. The results indicate that the relative efficiency of antibodies against ADV glycoproteins in protection should be considered for selecting or producing gene-deleted strains for use in vaccine production.

Interactions of pseudorabies virus with swine alveolar macrophages: effects of virus infection on cell functions

In order to assess the effect of pseudorabies virus (PRV) infection on the function of swine alveolar macrophages (AM), lung lavage cells were cultured, infected with one of six strains of PRV, and various activities were measured. Activity measurement included viability, phagocytosis of yeast, phagosome-lysosome fusion, phagocytosis of opsonized particles, and superoxide release. AM were infected with 5 x 10(-3) PFU/cell, and the comparative assessment of functions was performed at 18-20 h postinfection. Cell viability in PRV-infected cultures ranged from 79 to 94% of the viability in noninfected cultures. Phagocytosis of yeast was significantly reduced only in the AM cultures infected with the strain S-62. Phagosome-lysosome fusion was depressed in cultures infected with the strains S-62, 4892, 3816, and BUK. The phagocytosis of opsonized sheep red blood cells showed significant differences between noninfected and PRV-infected cultures in all cases except cultures infected with the strain PRV-C. The O2 release after stimulation with opsonized zymosan was significantly reduced in all the PRV-infected cultures. The effect of PRV infection on AM functions that are related to the bacterial activity of such cells suggests that PRV-induced AM dysfunction might have a role in the increased susceptibility of PRV-infected pigs to bacterial pneumonia.

Interactions of Pseudorabies virus with swine alveolar macrophages I: virus replication

The replication of Pseudorabies virus (PRV) in cultured swine alveolar macrophages (AM) was studied using 6 different virus strains. AM were highly permissive to PRV infection, with progeny virus titres of 10(7) TCID50/ml from some strains. Virus progeny titres were higher in cultures infected with the field strains S-62 and 4892 than in cultures infected with the strains Bartha or PRV-C. Virus replication, viral DNA synthesis and the concomitant cell damage were dependent upon virus input m.o.i.s. and virus strain. Furthermore, cells from 7 day old pigs yielded higher virus progeny titres than cells of 6 week old pigs. The results from this study provide support to the premise that PRV infection may predispose anials to respiratory disease.

In vitro comparison between four variants of Aujeszky's disease virus

Four Aujeszky's disease (pseudorabies) virus variants were characterized in vitro by investigation of their resistance to heat at 48 degrees C, sensitivity to trypsin and ability to replicate in pig alveolar macrophages, two of these variants (Ls-1 and Ls-2) were cloned previously from a single isolate of virus and showed differing pathogenicity for pigs; the virulent Stanley strain; and the non-virulent NIA-4 strain were included for comparison. Heat treatment produced slight decreases in infectivity but no significant differences were observed in the rates of inactivation. Both Ls-1 and Ls-2 were significantly more sensitive to trypsin treatment than the other two. The comparison of progeny virus titres after replication in alveolar macrophages allowed further differentiation among variants. Ls-1 and Ls-2 had similar titres in cultures infected with high virus input but in cultures infected with low virus input (0.1 TCID50/cell) Ls-1 produced higher titre. The difference in titres at 48 h post-infection was statistically significant (P less than 0.05). The cytopathogenicity for macrophages of the strains was correlated with their virulence for pigs, Stanley strain being the most cytopathogenic and NIA-4 the least.

Testing the response of a cardiac output meter using an artificial circulatory system

The variation in the response of a cardiac output flowmeter to several variables was investigated. An artificial circulatory system was constructed to give independent control of the variables. It was found that variations in the earlobe density, the amount of dye injected and the hematocrit value have little influence on the recorded flow which does, however, depend on the shape of the dilution curve. The values given by the instrument are too low for broad curves and too high for sharp ones, with an error of up to 25%.