2,181 research outputs found
Smectites versus palagonites in Mars soil: Evidence from simulations of Viking biology labeled release experiments
The results of an experimental comparison between palagonites and a smectite (montmorillonite) in the simulation of the Viking Biology Labeled Release (LR) experiment and conclusions regarding their suitability as MarSAMs are reproved. It was found that palagonites do not cause formate decomposition and C-14 release in their natural form or after acidification and thus cannot be a completely satisfactory analog to the Mars soil studied by Viking
A review of IATTC research on the early life history and reproductive biology of scombrids conducted at the Achotines Laboratory from 1985 to 2005
English:
For nearly a century, fisheries scientists have studied marine fish stocks in an effort to understand how the
abundances of fish populations are determined. During the early lives of marine fishes, survival is
variable, and the numbers of individuals surviving to transitional stages or recruitment are difficult to
predict.
The egg, larval, and juvenile stages of marine fishes are characterized by high rates of mortality and
growth. Most marine fishes, particularly pelagic species, are highly fecund, produce small eggs and
larvae, and feed and grow in complex aquatic ecosystems. The identification of environmental or
biological factors that are most important in controlling survival during the early life stages of marine
fishes is a potentially powerful tool in stock assessment.
Because vital rates (mortality and growth) during the early life stages of marine fishes are high and
variable, small changes in those rates can have profound effects on the properties of survivors and
recruitment potential (Houde 1989). Understanding and predicting the factors that most strongly
influence pre-recruit survival are key goals of fisheries research programs.
Spanish:
Desde hace casi un siglo, los cientÃficos pesqueros han estudiado las poblaciones de peces marinos en un
intento por entender cómo se determina la abundancia de las mismas. Durante la vida temprana de los
peces marinos, la supervivencia es variable, y el número de individuos que sobrevive hasta las etapas
transicionales o el reclutamiento es difÃcil de predecir.
Las etapas de huevo, larval, y juvenil de los peces marinos son caracterizadas por tasas altas de
mortalidad y crecimiento. La mayorÃa de los peces marinos, particularmente las especies pelágicas, son
muy fecundos, producen huevos y larvas pequeños, y se alimentan y crecen en ecosistemas acuáticos complejos. La identificación los factores ambientales o biológicos más importantes en el control de la
supervivencia durante las etapas tempranas de vida de los peces marinos es una herramienta
potencialmente potente en la evaluación de las poblaciones.
Ya que las tasas vitales (mortalidad y crecimiento) durante las etapas tempranas de vida de los peces
marinos son altas y variables, cambios pequeños en esas tasas pueden ejercer efectos importantes sobre
las propiedades de los supervivientes y el potencial de reclutamiento (Houde 1989). Comprender y
predecir los factores que más afectan la supervivencia antes del reclutamiento son objetivos clave de los
programas de investigación pesquera
Spawning and early development of captive yellowfin tuna (Thunnus albacares)
In this study we describe the courtship and spawning behaviors of captive yellowfin tuna (Thunnus albacares), their spawning periodicity, the influence of physical and biological factors on spawning and hatching, and egg and early-larval development of this species at the Achotines Laboratory, Republic of Panama, during October 1996 through March 2000. Spawning occurred almost daily over extended periods and at water temperatures from 23.3° to 29.7°C. Water temperature appeared to be the main exogenous factor controlling the occurrence and timing of spawning. Courtship and spawning behaviors were ritualized and consistent among three groups of broodstock over 3.5 years. For any date, the time of day of spawning (range: 1330 to 2130 h) was predictable from mean daily water temperature, and 95% of hatching occurred the next day between 1500 and 1900 h. We estimated that females at first spawning averaged 1.6−2.0 years of age. Over short time periods (<1 month), spawning females increased their egg production from 30% to 234% in response to shortterm increases in daily food ration of 9% to 33%. Egg diameter, notochord length (NL) at hatching, NL at first feeding, and dry weights of these stages were estimated. Water temperature was significantly, inversely related to egg size, egg-stage duration, larval size at hatching, and yolksac larval duration
Liability Protections for Emergency Volunteer Health Practitioners and Entities
Twenty-four states and D.C. have statutes that extend some level of immunity to groups and/or organizations providing charitable, emergency, or disaster relief services, although these laws varied greatly among states
Orale Mukositis bei Patienten unter Tumortherapie
Zusammenfassung: Zu den unerwünschten Nebenwirkungen bestimmter Chemo- und Radiotherapien gehört die orale Mukositis, eine Entzündung der Mundschleimhaut. Da sie die Lebensqualität der Patienten in hohem Maße beeinträchtigen kann, sollten Pflegende der Mundhygiene einen besonders hohen Stellenwert beimessen. In der täglichen Praxis wird die orale Mukositis oft kontrovers diskutiert. In diesem Artikel werden aktuelle theoriebasierte und erfahrungsbasierte Grundlagen und Anleitungen für die Pflege und Behandlung vorgestell
Controlled release delivery of penciclovir via a silicone (MED-4750) polymer: kinetics of drug delivery and efficacy in preventing primary feline herpesvirus infection in culture
Peripheral T-cell lymphoma (PTCL) represents a relatively rare group of heterogeneous non-Hodgkin lymphomas, with generally poor prognosis. Historically, there has been a lack of consensus regarding appropriate therapeutic measures for the disease, with conventional frontline chemotherapies being utilized in most cases. Following promising results obtained in 2009, the methotrexate analogue, pralatrexate, became the first drug to gain US FDA approval for the treatment of refractory PTCL. This antimetabolite was designed to have a higher affinity for reduced folate carrier (RFC) and folylpolyglutamate synthetase (FPGS). RFC is the principal transporter for cell entrance of folates and antifolates. Once inside the cell, pralatrexate is efficiently polyglutamated by FPGS. Pralatrexate has demonstrated varying degrees of efficacy in peripheral T-cell lymphoma, with response rates differing between the multiple subtypes of the disease. While phase III studies are still to be completed, early clinical trials indicate that pralatrexate is promising new therapeutic for PTCL
454-Pyrosequencing: A Molecular Battiscope for Freshwater Viral Ecology
Viruses, the most abundant biological entities on the planet, are capable of infecting organisms from all three branches of life, although the majority infect bacteria where the greatest degree of cellular diversity lies. However, the characterization and assessment of viral diversity in natural environments is only beginning to become a possibility. Through the development of a novel technique for the harvest of viral DNA and the application of 454 pyrosequencing, a snapshot of the diversity of the DNA viruses harvested from a standing pond on a cattle farm has been obtained. A high abundance of viral genotypes (785) were present within the virome. The absolute numbers of lambdoid and Shiga toxin (Stx) encoding phages detected suggested that the depth of sequencing had enabled recovery of only ca. 8% of the total virus population, numbers that agreed within less than an order of magnitude with predictions made by rarefaction analysis. The most abundant viral genotypes in the pond were bacteriophages (93.7%). The predominant viral genotypes infecting higher life forms found in association with the farm were pathogens that cause disease in cattle and humans, e.g. members of the Herpesviridae. The techniques and analysis described here provide a fresh approach to the monitoring of viral populations in the aquatic environment, with the potential to become integral to the development of risk analysis tools for monitoring the dissemination of viral agents of animal, plant and human diseases
Infrared spectroscopy of phytochrome and model pigments
Fourier-transform infrared difference spectra between the red-absorbing and far-red-absorbing forms of oat phytochrome have been measured in H2O and 2H2O. The difference spectra are compared with infrared spectra of model compounds, i.e. the (5Z,10Z,15Z)- and (5Z,10Z,15E)-isomers of 2,3,7,8,12,13,17,18-octaethyl-bilindion (Et8-bilindion), 2,3-dihydro-2,3,7,8,12,13,17,18-octaethyl-bilindion (H2Et8-bilindion), and protonated H2Et8-bilindion in various solvents. The spectra of the model compounds show that only for the protonated forms can clear differences between the two isomers be detected. Since considerable differences are present between the spectra of Et8-bilindion and H2Et8-bilindion, it is concluded that only the latter compound can serve as a model system of phytochrome. The 2H2O effect on the difference spectrum of phytochrome supports the view that the chromophore in red-absorbing phytochrome is protonated and suggests, in addition, that it is also protonated in far-red-absorbing phytochrome. The spectra show that protonated carboxyl groups are influenced. The small amplitudes in the difference spectra exclude major changes of protein secondary structure
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