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1.
Clim Change ; 170(3-4): 30, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35221398

RESUMO

Estimates of changes in the frequency or height of contemporary extreme sea levels (ESLs) under various climate change scenarios are often used by climate and sea level scientists to help communicate the physical basis for societal concern regarding sea level rise. Changes in ESLs (i.e., the hazard) are often represented using various metrics and indicators that, when anchored to salient impacts on human systems and the natural environment, provide useful information to policy makers, stakeholders, and the general public. While changes in hazards are often anchored to impacts at local scales, aggregate global summary metrics generally lack the context of local exposure and vulnerability that facilitates translating hazards into impacts. Contextualizing changes in hazards is also needed when communicating the timing of when projected ESL frequencies cross critical thresholds, such as the year in which ESLs higher than the design height benchmark of protective infrastructure (e.g., the 100-year water level) are expected to occur within the lifetime of that infrastructure. We present specific examples demonstrating the need for such contextualization using a simple flood exposure model, local sea level rise projections, and population exposure estimates for 414 global cities. We suggest regional and global climate assessment reports integrate global, regional, and local perspectives on coastal risk to address hazard, vulnerability and exposure simultaneously. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10584-021-03288-6.

2.
Clin Biochem ; 97: 11-24, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34453894

RESUMO

OBJECTIVES: There is a need for precision medicine and an unspoken promise of an optimal approach for identification of the right patients for value-based medicine based on big data. However, there may be a misconception that measurement of proteins is more valuable than measurement of fewer selected biomarkers. In population-based research, variation may be somewhat eliminated by quantity. However, this fascination of numbers may limit the attention to and understanding of the single. This review highlights that protein measurements (with collagens as examples) may mean different things depending on the targeted epitope - formation or degradation of tissues, and even signaling potential of proteins. DESIGN AND METHODS: PubMed was searched for collagen, neo-epitope, biomarkers. RESULTS: Ample examples of assays with specific epitopes, either pathological such as HbA1c, or domain specific such as pro-peptides, which total protein arrays would not have identified were evident. CONCLUSIONS: We suggest that big data may be considered as the funnel of data points, in which most important parameters will be selected. If the technical precision is low or the biological accuracy is limited, and we include suboptimal quality of biomarkers, disguised as big data, we may not be able to fulfill the promise of helping patients searching for the optimal treatment. Alternatively, if the technical precision of the total protein quantification is high, but we miss the functional domains with the most considerable biological meaning, we miss the most important and valuable information of a given protein. This review highlights that measurements of the same protein in different ways may provide completely different meanings. We need to understand the pathological importance of each epitope quantified to maximize protein measurements.


Assuntos
Doenças Cardiovasculares/metabolismo , Colágeno/imunologia , Epitopos , Proteínas/análise , Proteínas/metabolismo , Membrana Basal/metabolismo , Remodelação Óssea/imunologia , Colágeno/análise , Colágeno/metabolismo , Gastroenteropatias/metabolismo , Humanos , Rim/metabolismo , Cirrose Hepática/metabolismo , Neoplasias/imunologia , Prognóstico , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Proteínas/imunologia
3.
Respir Res ; 22(1): 38, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33546680

RESUMO

Pulmonary fibrosis has been identified as a main factor leading to pulmonary dysfunction and poor quality of life in post-recovery Severe Acute Respiratory Syndrome (SARS) survivor's consequent to SARS-Cov-2 infection. Thus there is an urgent medical need for identification of readily available biomarkers that in patients with SARS-Cov-2 infection are able to; (1) identify patients in most need of medical care prior to admittance to an intensive care unit (ICU), and; (2) identify patients post-infection at risk of developing persistent fibrosis of lungs with subsequent impaired quality of life and increased morbidity and mortality. An intense amount of research have focused on wound healing and Extracellular Matrix (ECM) remodelling of the lungs related to lung function decline in pulmonary fibrosis (PF). A range of non-invasive serological biomarkers, reflecting tissue remodelling, and fibrosis have been shown to predict risk of acute exacerbations, lung function decline and mortality in PF and other interstitial lung diseases (Sand et al. in Respir Res 19:82, 2018). We suggest that lessons learned from such PF studies of the pathological processes leading to lung function decline could be used to better identify patients infected with SARS-Co-V2 at most risk of acute deterioration or persistent fibrotic damage of the lung and could consequently be used to guide treatment decisions.


Assuntos
COVID-19/metabolismo , Matriz Extracelular/metabolismo , Fibrose Pulmonar/metabolismo , Cicatrização/fisiologia , Animais , Biomarcadores/metabolismo , COVID-19/diagnóstico , Humanos , Pulmão/metabolismo , Fibrose Pulmonar/diagnóstico
4.
Earths Future ; 8(3): e2019EF001340, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32715011

RESUMO

Deep uncertainty describes situations when there is either ignorance or disagreement over (1) models used to describe key system processes and (2) probability distributions used to characterize the uncertainty of key variables and parameters. Future projections of Antarctic ice sheet (AIS) mass loss remain characterized by deep uncertainty. This complicates decisions on long-lived coastal protection projects when determining what margin of safety to implement. If the chosen margin of safety does not properly account for uncertainties in sea level rise, the effectiveness of flood protection could decrease over time, potentially putting lives and properties at a greater risk. To address this issue, we develop a flood damage allowance framework for calculating the height of a flood protection strategy needed to ensure that a given level of financial risk is maintained. The damage allowance framework considers decision maker preferences such as planning horizons, protection strategies, and subjective views of AIS stability. We use Manhattan-with the population and built environment fixed in time-to illustrate how our framework could be used to calculate a range of damage allowances based on multiple plausible scenarios of AIS melt. Under high greenhouse gas emissions, we find that results are sensitive to the selection of the upper limit of AIS contributions to sea level rise. Design metrics that specify financial risk targets, such as expected flood damage, allow for the calculation of avoided flood damages (i.e., benefits) that can be combined with estimates of construction cost and then integrated into existing financial decision-making approaches (e.g., benefit-cost analysis).

5.
Nat Commun ; 11(1): 390, 2020 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-31959769

RESUMO

Uncertainties in Representative Concentration Pathway (RCP) scenarios and Antarctic Ice Sheet (AIS) melt propagate into uncertainties in projected mean sea-level (MSL) changes and extreme sea-level (ESL) events. Here we quantify the impact of RCP scenarios and AIS contributions on 21st-century ESL changes at tide-gauge sites across the globe using extreme-value statistics. We find that even under RCP2.6, almost half of the sites could be exposed annually to a present-day 100-year ESL event by 2050. Most tropical sites face large increases in ESL events earlier and for scenarios with smaller MSL changes than extratropical sites. Strong emission reductions lower the probability of large ESL changes but due to AIS uncertainties, cannot fully eliminate the probability that large increases in frequencies of ESL events will occur. Under RCP8.5 and rapid AIS mass loss, many tropical sites, including low-lying islands face a MSL rise by 2100 that exceeds the present-day 100-year event level.

6.
Proc Natl Acad Sci U S A ; 116(13): 6051-6056, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30858323

RESUMO

Old World monkeys (Cercopithecoidea) are a highly successful primate radiation, with more than 130 living species and the broadest geographic range of any extant group except humans. Although cercopithecoids are highly variable in habitat use, social behavior, and diet, a signature dental feature unites all of its extant members: bilophodonty (bi: two, loph: crest, dont: tooth), or the presence of two cross-lophs on the molars. This feature offers an adaptable Bauplan that, with small changes to its individual components, permits its members to process vastly different kinds of food. Old World monkeys diverged from apes perhaps 30 million years ago (Ma) according to molecular estimates, and the molar lophs are sometimes incompletely developed in fossil species, suggesting a mosaic origin for this key adaptation. However, critical aspects of the group's earliest evolution remain unknown because the cercopithecoid fossil record before ∼18 Ma consists of only two isolated teeth, one from Uganda and one from Tanzania. Here we describe a primitive Old World monkey from Nakwai, Kenya, dated at ∼22 Ma, that offers direct evidence for the initial key steps in the evolution of the cercopithecoid dentition. The simple dentition and absence of bilophodonty in the Nakwai monkey indicate that the initial radiation of Old World monkeys was first characterized by a reorganization of basic molar morphology, and a reliance on cusps rather than lophs suggests frugivorous diets and perhaps hard object feeding. Bilophodonty evolved later, likely in response to the inclusion of leaves in the diet.


Assuntos
Cercopithecidae/anatomia & histologia , Fósseis/anatomia & histologia , Dente/anatomia & histologia , Animais , Evolução Biológica , Dieta , Frutas , História Antiga , Quênia , Dente Molar/anatomia & histologia , Folhas de Planta
7.
Science ; 356(6345): 1362-1369, 2017 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-28663496

RESUMO

Estimates of climate change damage are central to the design of climate policies. Here, we develop a flexible architecture for computing damages that integrates climate science, econometric analyses, and process models. We use this approach to construct spatially explicit, probabilistic, and empirically derived estimates of economic damage in the United States from climate change. The combined value of market and nonmarket damage across analyzed sectors-agriculture, crime, coastal storms, energy, human mortality, and labor-increases quadratically in global mean temperature, costing roughly 1.2% of gross domestic product per +1°C on average. Importantly, risk is distributed unequally across locations, generating a large transfer of value northward and westward that increases economic inequality. By the late 21st century, the poorest third of counties are projected to experience damages between 2 and 20% of county income (90% chance) under business-as-usual emissions (Representative Concentration Pathway 8.5).

8.
Int J Obes (Lond) ; 40(4): 564-72, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26607040

RESUMO

BACKGROUND/OBJECTIVES: Recent findings have highlighted the detrimental influence of maternal overnutrition and obesity on fetal development and early life development. However, there are no evidence-based guidelines regarding the optimal strategy for dietary intervention before pregnancy. SUBJECTS/METHODS: We used a murine model to study whether switching from a high-fat (HF) diet to a normal-fat (NF) diet (H1N group) 1 week before pregnancy could lead to in utero reprogramming of female offspring obesity; comparator groups were offspring given a consistent maternal HF group or NF group until weaning. After weaning, all female offspring were given the HF diet for either 9 or 12 weeks before being killed humanely. RESULTS: H1N treatment did not result in maternal weight loss before pregnancy. NF offsprings were neither obese nor glucose intolerant during the entire experimental period. H1N offsprings were most obese after the 12-week postweaning HF diet and displayed glucose intolerance earlier than HF offsprings. Our mechanistic study showed reduced adipocyte insulin receptor substrate 1 (IRS1) and hepatic IRS2 expression and increased adipocyte p-Ser(636/639) and p-Ser(612) of H1N or HF offspring compared with that in the NF offspring. Among all groups, the H1N offspring had lowest level of IRS1 and the highest levels of p-Ser(636/639) and p-Ser(612) in gonadal adipocyte. In addition, the H1N offspring further reduced the expression of Glut4 and Glut2, vs those of the HF offspring, which was lower compared with the NF offspring. There were also enhanced expression of genes inhibiting glycogenesis and decreased hepatic glycogen in H1N vs HF or NF offspring. Furthermore, we showed extremely higher expression of lipogenesis and adipogenesis genes in gonadal adipocytes of H1N offspring compared with all other groups. CONCLUSIONS: Our results suggest that a transition from an HF diet to an NF diet shortly before pregnancy, without resulting in maternal weight loss, is not necessarily beneficial and may have deleterious effects on offspring.


Assuntos
Animais Recém-Nascidos/metabolismo , Dieta Hiperlipídica , Gorduras na Dieta/farmacologia , Fenômenos Fisiológicos da Nutrição Materna/efeitos dos fármacos , Obesidade/etiologia , Efeitos Tardios da Exposição Pré-Natal/etiologia , Fenômenos Fisiológicos da Nutrição Pré-Natal/efeitos dos fármacos , Animais , Gorduras na Dieta/administração & dosagem , Modelos Animais de Doenças , Feminino , Lactação , Masculino , Camundongos , Obesidade/patologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/patologia , Desmame
9.
Rev Sci Instrum ; 85(11): 11E805, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25430370

RESUMO

Compact condensed-matter injection technologies are increasingly used in magnetic fusion. One recent application is in disruption mitigation. An imaging system with less-than-100-µm- and sub-µs-resolution is described and used to characterize intact and shattered cryogenic neon pellets. Shattered pellets contain fine particles ranging from tens of µm to about 7 mm. Time-of-flight analyses indicate that pellets could slow down if hitting the wall of the guide tube. Fast high-resolution imaging systems are thus useful to neon and other condensed-matter injector development.

10.
Environ Sci Technol ; 47(24): 14258-66, 2013 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-24187951

RESUMO

Climate change is expected to increase global mean temperatures leading to higher tropospheric ozone (O3) concentrations in already polluted regions, potentially eroding the benefits of expensive emission controls. The magnitude of the "O3-climate penalty" has generally decreased over the past three decades, which makes future predictions for climate impacts on air quality uncertain. Researchers attribute historical reductions in the O3-climate penalty to reductions in NOx emissions but have so far not extended this theory into a quantitative prediction for future effects. Here, we show that a three-dimensional air quality model can be used to map the behavior of the O3-climate penalty under varying NOx and VOC emissions in both NOx-limited and NOx-saturated conditions in Central and Southern California, respectively. Simulations suggest that the planned emissions control program for O3 precursors will not diminish the O3-climate penalty to zero as some observational studies might imply. The results further demonstrate that in a NOx-limited air basin, NOx control strategies alone are sufficient to both decrease the O3-climate penalty and mitigate O3 pollution, while in a NOx-saturated air basin, a modified emissions control plan that carefully chooses reductions in both NOx and VOC emissions may be necessary to eliminate the O3-climate penalty while simultaneously reducing base case O3 concentrations to desired levels. Additional modeling is needed to determine the behavior of the O3-climate penalty as NOx and VOC emissions evolve in other regions.


Assuntos
Clima , Modelos Teóricos , Ozônio/análise , Poluentes Atmosféricos/análise , Poluição do Ar/análise , California , Nitratos/análise , Nitritos/análise , Compostos Orgânicos Voláteis/análise
11.
Am J Primatol ; 75(2): 95-106, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23184701

RESUMO

In 1974, Cartmill introduced the theory that the earliest primate adaptations were related to their being visually oriented predators active on slender branches. Given more recent data on primate-like marsupials, nocturnal prosimians, and early fossil primates, and the context in which these primates first appeared, this theory has been modified. We hypothesize that our earliest primate relatives were likely exploiting the products of co-evolving angiosperms, along with insects attracted to fruits and flowers, in the slender supports of the terminal branch milieu. This has been referred to as the primate/angiosperm co-evolution theory. Cartmill subsequently posited that: "If the first euprimates had grasping feet and blunt teeth adapted for eating fruit, but retained small divergent orbits…" then the angiosperm coevolution theory would have support. The recent discovery of Carpolestes simpsoni provides this support. In addition, new field data on small primate diets, and a new theory concerning the visual adaptations of primates, have provided further evidence supporting the angiosperm coevolution theory.


Assuntos
Evolução Biológica , Cadeia Alimentar , Magnoliopsida/fisiologia , Primatas/fisiologia , Animais , Dieta , Comportamento Alimentar , Fósseis , Magnoliopsida/anatomia & histologia , Magnoliopsida/genética , Primatas/anatomia & histologia , Primatas/genética , Vias Visuais/anatomia & histologia , Vias Visuais/fisiologia
12.
J Emerg Med ; 43(3): 413-6, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22032813

RESUMO

BACKGROUND: The National Registry of Myocardial Infarction reported that only 4% of patients transferred for primary percutaneous coronary intervention (PCI) achieved the recommendation of a door-to-balloon time of < 90 min. OBJECTIVES: To see if the American College of Cardiologists/American Heart Association (ACC/AHA) guideline of < 90 min door-to-balloon time for primary PCI is being met in a rural area of West Virginia, and compare to the national average. METHODS: A chart review of all cases of emergent primary PCI for ST-segment elevation myocardial infarction (STEMI) performed in the northern panhandle of West Virginia. RESULTS: The northern panhandle of West Virginia has seven hospitals, of which only one has the capability to perform primary PCI. Two hundred two patients underwent emergent PCI for STEMI from January 1, 2009-September 11, 2010. For each patient, the initial presenting time, arrival time to the PCI hospital, and start of PCI time were recorded. Eight patients were eliminated from the study for not having an initial presenting time. Of the remaining 194 patients, 89 were transferred for primary PCI. Forty-nine patients met the ACC/AHA recommendation of < 90 min door-to-balloon time. The average door-to-balloon time for patients transferred for primary PCI was 104.9 min (Standard Deviation [STD]. 58.2219, 95% confidence interval 92.85-117.04). CONCLUSION: Fifty-five percent of patients transferred for primary PCI in the northern panhandle of West Virginia met the recommended guidelines. This is an improvement on the national average of 4%.


Assuntos
Infarto do Miocárdio/terapia , Intervenção Coronária Percutânea , Serviços de Saúde Rural/estatística & dados numéricos , Tempo para o Tratamento/estatística & dados numéricos , Fidelidade a Diretrizes , Humanos , Infarto do Miocárdio/epidemiologia , Guias de Prática Clínica como Assunto , West Virginia/epidemiologia
13.
W V Med J ; 107(5): 22-5, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22034806

RESUMO

There has been speculation that third generation hormonal contraceptives may be less prone to inducing clotting than the earlier generation products. We present a case of colonic ischemia in a young adolescent receiving pharmacotherapy with a third-generation hormonal contraceptive. Ischemic colitis is an uncommon adverse effect in young adolescents associated with hormonal contraception, especially the third generation agents. We believe this case to be the second-youngest patient reported with ischemic colitis due to this therapy. Clinical vigilance is recommended for women presenting with abdominal pain, with or without hematochezia, who are receiving hormonal contraceptive therapy. Since their introduction in the early 1960's, the combination hormonal contraceptives have been utilized by millions of women for both contraceptive and non-contraceptive purposes. Although a variety of adverse effects can be experienced by individuals taking these agents, it has been demonstrated that these agents are associated with an increased risk of venous and arterial thromboses. Publications more consistently report on the cardiovascular-, pulmonary-, peripheral vascular-, or cerebrovascular-based thrombotic events associated with these agents. During the past several decades changes have been incorporated in the dose and types of compounds included in the combination hormonal contraceptive products in an attempt to reduce the risk of coagulation and other adverse effects. Less common and less frequently publicized are the gastrointestinal-based thrombotic events that result in ischemia and presents as severe abdominal pain, with or without hematochezia. We report an uncommon case of reversible colonic ischemia in who we believe to be the second-youngest adolescent female reported in the literature (youngest aged 16 years) to have this diagnosis associated with the use of a newer, third-generation oral combination hormonal contraceptive (Naranjo scale of 7; Probable).


Assuntos
Colite Isquêmica/induzido quimicamente , Anticoncepcionais Orais Hormonais/efeitos adversos , Adolescente , Colite Isquêmica/diagnóstico , Colite Isquêmica/terapia , Feminino , Humanos
14.
J Am Osteopath Assoc ; 111(6): 407-9, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21771928

RESUMO

A limited number of cases have been reported in the medical literature in which aortic dissection occurs with an aberrant right subclavian artery and a common carotid trunk. The authors report the case of a 59-year-old man who presented to the emergency department with sudden onset pain of 30 minutes duration on the right side of the buttocks. After presentation, the patient developed chest pain, which radiated to the back. Computed tomography angiogram revealed a Stanford type A aortic dissection that extended down to the bifurcation of the iliac arteries. He was also found to have an aberrant right subclavian artery with a retroesophageal tract and a common trunk of the common carotid arteries. The patient was transferred to a tertiary care center and underwent surgery for aortic arch replacement. The authors also discuss the embryologic development of these vascular abnormalities.


Assuntos
Aneurisma Aórtico/cirurgia , Dissecção Aórtica/cirurgia , Artéria Subclávia/cirurgia , Dissecção Aórtica/diagnóstico por imagem , Aneurisma Aórtico/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Artéria Subclávia/patologia
15.
Rev Sci Instrum ; 81(10): 10E527, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21034055

RESUMO

The state of the art in electro-optics has advanced to the point where digital holographic acquisition of wavefronts is now possible. Holographic wavefront acquisition provides the phase of the wavefront at every measurement point. This can be done with accuracy on the order of a thousandth of a wavelength, given that there is sufficient care in the design of the system. At wave frequencies which are much greater than the plasma frequency, the plasma index of refraction is linearly proportional to the electron density and wavelength, and the measurement of the phase of a wavefront passing through the plasma gives the chord-integrated density directly for all points measured on the wavefront. High-speed infrared cameras (up to ∼40,000 fps at ∼64×4 pixels) with resolutions up to 640×512 pixels suitable for use with a CO(2) laser are readily available, if expensive.

16.
Diabetologia ; 53(12): 2569-78, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20878317

RESUMO

AIMS/HYPOTHESIS: Cytokine-induced beta cell toxicity is abrogated by non-selective inhibitors of lysine deacetylases (KDACs). The KDAC family consists of 11 members, namely histone deacetylases HDAC1 to HDAC11, but it is not known which KDAC members play a role in cytokine-mediated beta cell death. The aim of the present study was to examine the KDAC gene expression profile of the beta cell and to investigate whether KDAC expression is regulated by cytokines. In addition, the protective effect of the non-selective KDAC inhibitor ITF2357 and interdependent regulation of four selected KDACs were investigated. METHODS: The beta cell line INS-1 and intact rat and human islets were exposed to cytokines with or without ITF2357. Expression of mRNA was assessed by real-time PCR and selected targets validated at the protein level by immunoblotting. Effects on cytokine-induced toxicity were investigated by in vitro assays. RESULTS: Hdac1 to Hdac11 were expressed and differentially regulated by cytokines in INS-1 cells and rat islets. HDAC1, -2, -6 and -11 were found to be expressed and regulated by cytokines in human islets. ITF2357 protected against cytokine-induced beta cell apoptosis and counteracted cytokine-induced attenuation of basal insulin secretion. In addition, cytokine-induced regulation of Hdac2 and Hdac6, but not Hdac1 and Hdac11, was reduced by KDAC inhibition. CONCLUSIONS/INTERPRETATION: All classical KDAC genes are expressed by beta cells and differentially regulated by cytokines. Based on the relative expression levels and degree of regulation by cytokines, we propose that HDAC1, -2, -6 and -11 are of particular importance for beta cell function. These observations may help in the design of specific KDAC inhibitors to prevent beta cell destruction in situ and in islet grafts.


Assuntos
Citocinas/farmacologia , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Mediadores da Inflamação/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Lisina/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Células Cultivadas , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Humanos , Ratos , Ratos Wistar , Fatores de Tempo
17.
Rev Sci Instrum ; 79(10): 10F321, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19044634

RESUMO

A compact pellet injector is being built for the TJ-II stellarator. It is an upgraded version of the "pellet injector in a suitcase" developed at Oak Ridge National Laboratory and installed on the Madison Symmetric Torus where it continues to be used in many plasma experiments. The design aim is to provide maximum flexibility at minimal cost, while allowing for future upgrades. It is a four-barrel system equipped with a cryogenic refrigerator for in situ hydrogen pellet formation, a combined mechanical punch/propellant valve system, pellet diagnostics, and an injection line, destined for use as an active diagnostic and for fueling. In order to fulfill both objectives it will be sufficiently flexible to permit pellets, with diameters from 0.4 to 1 mm, to be fabricated and accelerated to velocities from 150 to approximately 1000 m s(-1).

18.
Int J Infrared Millimeter Waves ; 29(11): 1011-1018, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19081774

RESUMO

We report the measurement of small losses in transmission line (TL) components intended for high-power millimeter-wave applications. Measurements were made using two different low-power techniques: a coherent technique using a vector network analyzer (VNA) and an incoherent technique using a radiometer. The measured loss in a 140 GHz 12.7 mm diameter TL system, consisting of 1.7 m of circular corrugated waveguide and three miter bends, is dominated by the miter bend loss. The measured loss was 0.3±0.1 dB per miter bend using a VNA; and 0.22±0.1 dB per miter bend using a radiometer. Good agreement between the two measurement techniques implies that both are useful for measuring small losses. To verify the methodology, the VNA technique was employed to measure the extremely small transmission loss in a 170 GHz ITER prototype TL system consisting of three lengths of 1 m, 63.5 mm diameter, circular corrugated waveguide and two miter bends. The measured loss of 0.05±0.02 dB per miter bend may be compared with the theoretical loss of 0.027 dB per miter bend. These results suggest that low-power testing of TL losses, utilizing a small, simple TL system and a VNA, is a reliable method for evaluating performance of low-loss millimeter-wave TL components intended for use in high-power applications.

19.
Am J Phys Anthropol ; Suppl 47: 100-17, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19003895

RESUMO

Much of the recent research on the evolution of primate visual systems has assumed that a minimum number of shifts have occurred in circadian activity patterns over the course of primate evolution. The evolutionary origins of key higher taxonomic groups have been interpreted by some researchers as a consequence of a rare shift from nocturnality to diurnality (e.g., Anthropoidea) or from diurnality to nocturnality (e.g., Tarsiidae). Interpreting the evolution of primate visual systems with an ecological approach without parsimony constraints suggests that the evolutionary transitions in activity pattern are more common than what would be allowed by parsimony models, and that such transitions are probably less important in the origin of higher level taxa. The analysis of 17 communities of primates distributed widely around the world and through geological time shows that primate communities consistently contain both nocturnal and diurnal forms, regardless of the taxonomic sources of the communities. This suggests that primates in a community will adapt their circadian pattern to fill empty diurnal or nocturnal niches. Several evolutionary transitions from one pattern to the other within narrow taxonomic groups are solidly documented, and these cases probably represent a small fraction of such transitions throughout the Cenozoic. One or more switches have been documented among platyrrhine monkeys, Malagasy prosimians, Eocene omomyids, Eocene adapoids, and early African anthropoids, with inconclusive but suggestive data within tarsiids. The interpretation of living and extinct primates as fitting into one of two diarhythmic categories is itself problematic, because many extant primates show significant behavioral activity both nocturnally and diurnally. Parsimony models routinely interpret ancestral primates to have been nocturnal, but analyses of morphological and genetic data indicate that they may have been diurnal, or that early primate radiations were likely to have generated both nocturnal and diurnal forms, especially given the unusual annual light regimes faced by Early Tertiary primates living outside today's latitudinal tropics. We review the essential morphology and physiology of the primate visual system to look for features that might constrain evolutionary switches, and we find that the pattern of variation within and among primate groups in eye size, corneal size, retinal morphology, and opsin distribution are all consistent with the idea that there is considerable evolutionary flexibility in the visual system. These results suggest that primate lineages may evolve from diurnal to nocturnal, and vice versa, more readily and more rapidly than has been suggested by the use of strict parsimony models. This has implications for interpreting the fossil record and reconstructing key evolutionary events in primate evolution.


Assuntos
Ciclos de Atividade , Ritmo Circadiano , Evolução Cultural , Primatas , Retina , Visão Ocular , Animais , Ciclos de Atividade/fisiologia , Catarrinos/fisiologia , Cercopithecus/fisiologia , Ritmo Circadiano/fisiologia , Escuridão , Ecossistema , Haplorrinos/fisiologia , Luz , Opsinas/fisiologia , Primatas/fisiologia , Retina/fisiologia , Visão Ocular/fisiologia , Humanos
20.
Am J Phys Anthropol ; 131(3): 303-10, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16617428

RESUMO

North American omomyids represent a tremendous Eocene radiation of primates exhibiting a wide range of body sizes and dietary patterns. Despite this adaptive diversity, relatively little is known of the postcranial specializations of the group. Here we describe hindlimb and foot bones of Ourayia uintensis and Chipetaia lamporea that were recovered from the Uinta B member (early Uintan Land Mammal Age), Uinta Formation, Utah. These specimens provide insights into the evolution of postcranial adaptations across different body sizes and dietary guilds within the Eocene primate radiation. Body mass estimates based on talar measurements indicate that Ourayia uintensis and Chipetaia lamporea weighed about 1,500-2,000 g and 500-700 g, respectively. Skeletal elements recovered for Ourayia include the talus, navicular, entocuneiform, first metatarsal, and proximal tibia; bones of Chipetaia include the talus, navicular, entocuneiform, and proximal femur. Both genera had opposable grasping big toes, as indicated by the saddle-shaped joint between the entocuneiform and first metatarsal. Both taxa were arboreal leapers, as indicated by a consistent assemblage of characters in all represented bones, most notably the somewhat elongated naviculars, the high and distinct trochlear crests of the talus, the posteriorly oriented tibial plateau (Ourayia), and the cylindrical head of the femur (Chipetaia). The closest resemblances to Ourayia and Chipetaia are found among the Bridger omomyines, Omomys and Hemiacodon. The results of our comparisons suggest that the later, larger, more herbivorous omomyines from Utah retained a skeletal structure characteristic of earlier, smaller North American omomyids.


Assuntos
Osso e Ossos/anatomia & histologia , Fósseis , Primatas/anatomia & histologia , Adaptação Fisiológica , Animais , Pé/anatomia & histologia , Antropologia Forense , Membro Posterior/anatomia & histologia , Ossos do Metatarso/anatomia & histologia , Ossos do Tarso/anatomia & histologia , Tarso Animal/anatomia & histologia , Tíbia/anatomia & histologia , Utah
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