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Natural sounds, and bird song in particular, play a key role in building and maintaining our connection with nature, but widespread declines in bird populations mean that the acoustic properties of natural soundscapes may be changing. Using data-driven reconstructions of soundscapes in lieu of historical recordings, here we quantify changes in soundscape characteristics at more than 200,000 sites across North America and Europe. We integrate citizen science bird monitoring data with recordings of individual species to reveal a pervasive loss of acoustic diversity and intensity of soundscapes across both continents over the past 25 years, driven by changes in species richness and abundance. These results suggest that one of the fundamental pathways through which humans engage with nature is in chronic decline, with potentially widespread implications for human health and well-being.
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Acústica , Aves/fisiologia , Vocalização Animal/fisiologia , Animais , Biodiversidade , Aves/classificação , Conservação dos Recursos Naturais , Europa (Continente) , Humanos , América do Norte , Dinâmica Populacional , Estações do Ano , Som , Vocalização Animal/classificaçãoRESUMO
A carbon dioxide and nitrous oxide solid solution has been captured in a diamond anvil cell following the thermal decomposition of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) at high temperatures and pressures. This is the first time a carbon dioxide binary solid has been observed at high pressure. This observation has stimulated low temperature crystallographic studies of this binary system using recently developed gas absorption apparatus and computational modelling.
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Ever since the introduction of radiographic imaging, its utility in identifying injuries has been well documented and was incorporated in the workup of injured patients during advanced trauma life support algorithms [American College of Surgeons, 8th ed. Chicago, 2008]. More recently, computerized tomography (CT) has been shown to be more sensitive than radiography in the diagnosis of injury. Due to the increased use of CT scanning, concerns were raised regarding the associated exposure to ionizing radiation [N Engl J Med 357:2277-2284, 2007]. During the last several years, a significant amount of research has been published on this topic, most of it being incorporated in the BEIR VII Phase 2 report, published by the National Research Council of the National Academies [National Academy of Sciences, Washington DC, 2006]. The current review will analyze the scientific basis for the concerns over the ionizing radiation associated with the use of CT scanning and will examine the accuracy of the typical advanced trauma life support work-up for diagnosis of injuries.
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We present a methodology for extracting phonon data from ab initio Born-Oppenheimer molecular dynamics calculations of molecular crystals. Conventional ab initio phonon methods based on perturbations are difficult to apply to lattice modes because the perturbation energy is dominated by intramolecular modes. We use constrained molecular dynamics to eliminate the effect of bond bends and stretches and then show how trajectories can be used to isolate and define in particular, the eigenvalues and eigenvectors of modes irrespective of their symmetry or wave vector. This is done by k-point and frequency filtering and projection onto plane wave states. The method is applied to crystalline ammonia: the constrained molecular dynamics allows a significant speed-up without affecting structural or vibrational modes. All Gamma point lattice modes are isolated: the frequencies are in agreement with previous studies; however, the mode assignments are different.
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PURPOSE: To evaluate the ability of scanning laser polarimetry to discriminate between subjects with glaucoma with specific patterns of visual field defect and normal controls. METHODS: This cross-sectional, prospective study in a glaucoma practice, focused on subjects with glaucoma with predefined types of visual field defect, including advanced (group A, n = 14), localized (group L, n = 46), or mixed (diffuse and localized) defects (group M, n = 22) and normal controls (n = 32). Scanning laser polarimetry was performed in one study eye per subject. Two methods of analysis were used: a subjective analysis, in which examination printouts with the image of the optic disk manually blocked were classified by two observers masked to the diagnosis, and a logistic regression analysis of the retardation parameters included in the printouts. RESULTS: The observers correctly identified 97% of the controls and 68% of subjects with glaucoma (overall correct classification of 77%), with 93%, 70%, and 47% of patients from groups A, L, and M, respectively, being correctly identified. The best discrimination obtained with the logistic regression correctly identified 69% of controls and 94% of glaucoma subjects (overall correct classification of 87%). The performance was only slightly better for cases from group A compared with L and M. CONCLUSIONS: Subjective assessment of the scanning laser polarimetry standard printout of single eyes might not be sensitive enough to detect cases of glaucoma with localized or milder mixed types of visual field defect. The discriminating ability of scanning laser polarimetry improves slightly when logistic regression analysis is employed.
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Técnicas de Diagnóstico Oftalmológico , Glaucoma de Ângulo Aberto/diagnóstico , Transtornos da Visão/diagnóstico , Campos Visuais , Estudos Transversais , Análise Discriminante , Feminino , Humanos , Lasers , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Disco Óptico/patologia , Estudos Prospectivos , Sensibilidade e EspecificidadeRESUMO
The molecular structures of the stable phosphinyl and arsinyl radicals, .PnR(2) [Pn = P (2); As (4); R = CH(SiMe(3))(2)], have been determined by gas-phase electron diffraction (GED) in conjunction with ab initio molecular orbital calculations. The X-ray crystal structures of the corresponding dipnictines, the "dimers", R(2)PnPnR(2) [Pn = P (1), As (3)], and the chloro derivatives R(2)PnCl [Pn = P (5), As (6)] have also been determined. Collectively, these structural investigations demonstrate that large distortions of the ligands attached to Pn occur when the pnictinyl radicals unite to form the corresponding dipnictine dimers. Principally, it is the shape and flexibility of the CH(SiMe(3))(2) ligands that permit the formation of the P-P and As-As bonds in 1and 3, respectively. However, theoretical studies indicate that in the process of pnictinyl radical dimerization to form 1 and 3, both molecules accumulate substantial amounts of potential energy and are thus primed to spring apart upon release from the solid state by melting, dissolution, or evaporation. The insights gleaned from these unusual systems have permitted a deeper understanding of the functioning of sterically demanding substituents.
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Gallaborane (GaBH(6), 1), synthesized by the metathesis of LiBH(4) with [H(2)GaCl](n) at ca. 250 K, has been characterized by chemical analysis and by its IR and (1)H and (11)B NMR spectra. The IR spectrum of the vapor at low pressure implies the presence of only one species, viz. H(2)Ga(mu-H)(2)BH(2), with a diborane-like structure conforming to C(2v) symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements afforced by the results of ab initio molecular orbital calculations. Hence the principal distances (r(alpha) in A) and angles ( angle(alpha) in deg) are as follows: r(Ga.B), 2.197(3); r(Ga-H(t)), 1.555(6); r(Ga-H(b)), 1.800(6); r(B-H(t)), 1.189(7); r(B-H(b)), 1.286(7); angleH(b)-Ga-H(b), 71.6(4); and angleH(b)-B-H(b), 110.0(5) (t = terminal, b = bridging). Aggregation of the molecules occurs in the condensed phases. X-ray crystallographic studies of a single crystal at 110 K reveal a polymeric network with helical chains made up of alternating pseudotetrahedral GaH(4) and BH(4) units linked through single hydrogen bridges; the average Ga.B distance is now 2.473(7) A. The compound decomposes in the condensed phases at temperatures exceeding ca. 240 K with the formation of elemental Ga and H(2) and B(2)H(6). The reactions with NH(3), Me(3)N, and Me(3)P are also described.
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Exercise testing can provide valuable information to aid the primary care physician in developing a safe and effective exercise program for his or her patients. This review presents the most recent recommendations for the components of an exercise program as well as methods to accomplish appropriate prescription writing for the various subsets of individuals from the healthy patient to the patient with chronic disease. In addition, a plea is made for physicians to encourage all patients to engage in at least some kind of regular exercise activity in an attempt to counteract the increasingly sedentary lifestyles found in our culture.
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Teste de Esforço , Terapia por Exercício , Frequência Cardíaca , Humanos , Aptidão Física , Atenção Primária à SaúdeAssuntos
Licenciamento em Enfermagem , Profissionais de Enfermagem/legislação & jurisprudência , Assistentes de Enfermagem/legislação & jurisprudência , Supervisão de Enfermagem/legislação & jurisprudência , Humanos , Descrição de Cargo , Responsabilidade Legal , Licenciamento em Enfermagem/legislação & jurisprudência , Papel do Profissional de Enfermagem , Assistentes de Enfermagem/educação , Assistentes de Enfermagem/provisão & distribuição , Admissão e Escalonamento de Pessoal/legislação & jurisprudência , Estados UnidosRESUMO
BACKGROUND: Pneumococcal vaccination after splenectomy for trauma decreases the incidence of overwhelming postsplenectomy infection. The optimal timing of vaccination has not been established. This study was conducted to determine whether timing of vaccination after splenectomy affects antibody response or survival after pneumococcal challenge. METHODS: Sprague-Dawley rats were used for all experiments. Control rats (n=30) were divided into three equal groups and underwent splenectomy followed by sham vaccination 1, 7, or 42 days after splenectomy. Treated rats (n=66) were divided into three equal groups and underwent splenectomy followed by vaccination with polyvalent pneumococcal vaccine 1, 7, or 42 days after splenectomy. All rats then underwent intraperitoneal Streptococcus pneumoniae inoculation with the predetermined lethal dose for 50% of the population 10 days after vaccination. Rats were observed for a 72-hour period after inoculation, and mortality was recorded. Immunoglobulin G and immunoglobulin M antibody titers were determined before vaccination and before inoculation to determine antibody response. RESULTS: Mortality was greater in the control group than in the treatment group (21 of 30 [70%] vs. 2 of 64 [3%]; p < 0.01). There were no differences in mortality within either the control group (1 day, 6 of 10; 7 days, 7 of 10; 42 days, 8 of 10; p=0.62) or the treatment group (1 day, 0 of 21; 7 days, 0 of 21; 42 days, 2 of 22; p=0.14). Immunoglobulin G and immunoglobulin M antibody responses were greater in vaccinated than in nonvaccinated rats. There was no effect of timing of vaccination on antibody response. CONCLUSION: Pneumococcal vaccine reduces mortality from postsplenectomy infection. Timing of vaccination after splenectomy does not affect survival from a pneumococcal challenge or antibody response in rats. This study supports the practice of administering vaccine within 24 hours of splenectomy when vaccine cannot be administered before surgery.
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Anticorpos Antibacterianos/sangue , Vacinas Bacterianas/administração & dosagem , Infecções Pneumocócicas/prevenção & controle , Complicações Pós-Operatórias/prevenção & controle , Streptococcus pneumoniae/imunologia , Animais , Vacinas Bacterianas/imunologia , Esquemas de Imunização , Masculino , Infecções Pneumocócicas/imunologia , Infecções Pneumocócicas/mortalidade , Vacinas Pneumocócicas , Complicações Pós-Operatórias/imunologia , Complicações Pós-Operatórias/mortalidade , Ratos , Ratos Sprague-Dawley , EsplenectomiaRESUMO
BACKGROUND: Laparoscopic herniorrhaphy may be performed using an intraperitoneal or a preperitoneal approach. Anecdotal and experimental evidence indicates that alterations in lower extremity venous flow, which occur during intraperitoneal laparoscopic insufflation, may be associated with an increased risk of deep vein thrombosis. However, no study has directly compared femoral venous flow during intraperitoneal insufflation with that during preperitoneal insufflation. METHOD: In eight consecutive patients undergoing laparoscopic herniorrhaphy under general anesthesia, flow through the common femoral vein was evaluated with B-mode and color flow duplex. Pre- and intraperitoneal pressures were standardized to 10 mm Hg, and respiratory tidal volumes were standardized to 10 cc/kg. Flow measurements were taken at end expiration. Flow through the common femoral vein was measured after induction of anesthesia, during intraperitoneal insufflation, during preperitoneal insufflation, and between insufflations to ensure return to baseline. RESULTS: All patients in the study were males. Their mean age was 59 years. Mean flow in the common femoral vein was essentially identical at baseline (138 ml/min) and during preperitoneal insufflation (135 ml/min). Alternatively, mean flow in the common femoral vein was significantly reduced during intraperitoneal insufflation (65 ml/min, p = 0.02). CONCLUSIONS: Flow in the common femoral vein is significantly reduced during intraperitoneal insufflation. However, flow in the common femoral vein is not affected by preperitoneal insufflation. These data suggest that laparoscopic preperitoneal inguinal hernia repair may pose as less a risk of thromboembolic complications than laparoscopic intraperitoneal inguinal hernia repair.
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Veia Femoral/fisiopatologia , Hérnia Inguinal/cirurgia , Laparoscopia/métodos , Pneumoperitônio Artificial , Adulto , Idoso , Idoso de 80 Anos ou mais , Velocidade do Fluxo Sanguíneo , Veia Femoral/diagnóstico por imagem , Hemodinâmica , Hérnia Inguinal/diagnóstico , Hérnia Inguinal/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Intraoperatória , Pneumoperitônio Artificial/métodos , Fluxo Sanguíneo Regional , Sensibilidade e Especificidade , Ultrassonografia Doppler em CoresRESUMO
Approximately 500,000 people suffer a new or recurrent brain attack each year. Despite advanced treatments, stroke continues to be the third leading cause of death in the United States. Survivors of stroke experience many different clinical problems and neurological deficits. Individual symptomatology varies according to specific vessel involvement and the location of brain tissue infarction or hemorrhage. Understanding basic cerebral anatomy provides a foundation for the neuroscience nurse to plan effective nursing care for the victim of brain attack.