47 research outputs found

    Comparison between active sensor and radiosonde cloud boundaries over the ARM Southern Great Plains site

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    In order to test the strengths and limitations of cloud boundary retrievals from radiosonde profiles, 4 years of radar, lidar, and ceilometer data collected at the Atmospheric Radiation Measurements Southern Great Plains site from November 1996 through October 2000 are used to assess the retrievals of Wang and Rossow [1995] and Chernykh and Eskridge [1996]. The lidar and ceilometer data yield lowest-level cloud base heights that are, on average, within approximately 125 m of each other when both systems detect a cloud. These quantities are used to assess the accuracy of coincident cloud base heights obtained from radar and the two radiosonde-based methods applied to 200 m resolution profiles obtained at the same site. The lidar/ceilometer and radar cloud base heights agree by 0.156 ± 0.423 km for 85.27% of the observations, while the agreement between the lidar/ceilometer and radiosonde-derived heights is at best −0.044 ± 0.559 km for 74.60% of all cases. Agreement between radar- and radiosonde-derived cloud boundaries is better for cloud base height than for cloud top height, being at best 0.018 ± 0.641 km for 70.91% of the cloud base heights and 0.348 ± 0.729 km for 68.27% of the cloud top heights. The disagreements between radar- and radiosonde-derived boundaries are mainly caused by broken cloud situations when it is difficult to verify that drifting radiosondes and fixed active sensors are observing the same clouds. In the case of the radar the presence of clutter (e.g., vegetal particles or insects) can affect the measurements from the surface up to approximately 3–5 km, preventing comparisons with radiosonde-derived boundaries. Overall, Wang and Rossow [1995] tend to classify moist layers that are not clouds as clouds and both radiosonde techniques report high cloud top heights that are higher than the corresponding heights from radar

    Reproduction in Heteroteuthis dispar (Rüppell, 1844) (Mollusca: Cephalopoda): a sepiolid reproductive adaptation to an oceanic lifestyle

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    Small cephalopods of the genus Heteroteuthis are the most pelagic members in the family Sepiolidae. This study examines the reproductive biology of Heteroteuthis dispar (Rüppell, 1844), the first such study on any member of the genus, based on 46 specimens (27 females and 19 males) collected during the Mar-Eco cruise in the North Atlantic in the region of the Mid-Atlantic Ridge in 2004, and compares it with reproductive features in the less pelagic members of the family. The unusually large spermatophores of the males have a very small ejaculatory apparatus and cement body, relative to the size of the sperm mass. Females first mate when they are still maturing: a large sperm mass (up to 3.4% of the female body mass), consisting of one to several spermatangia, was found in an internal seminal receptacle of the majority of the females examined regardless of their maturity state. The seminal receptacle has a unique form and position in this species. The receptacle is a thin-walled sac at the posterior end of the visceral mass that is an outpocketing of, and opens into, the visceropericardial coelom. Spermatangia and sperm from the spermatangia apparently enter into the visceropericardial coelom (which is mostly occupied by the ovary) from the seminal receptacle indicating that ova are fertilised internally, a strategy unknown for decapodiform cephalopods (squid and cuttlefish), but present in most octopods. Fecundity of Heteroteuthis dispar (1,100–1,300 oocytes) is much higher than in other sepiolids whereas the egg size (mean max. length ∼1.6 mm) is the smallest within the family. Spawning is continuous (sensu Rocha et al. in Biol Rev 76:291–304, 2001). These and other reproductive traits are discussed as being adaptations to an oceanic lifestyle

    Sperm transfer or spermatangia removal: postcopulatory behaviour of picking up spermatangium by female Japanese pygmy squid

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    In the Japanese pygmy squid Idiosepius paradoxus, females often pick up the spermatangium using their mouth (buccal mass) after copulation. To examine whether the female I. paradoxus directly transfers sperm into the seminal receptacle via this picking behaviour, or removes the spermatangium, we conducted detailed observations of picking behaviour in both virgin and copulated females and compared the sperm storage conditions in the seminal receptacle between females with and without spermatangia picking after copulation in virgin females. In all observations, elongation of the buccal mass occurred within 5 min after copulation. However, sperm volume in the seminal receptacle was not related to spermatangia picking. Observations using slow-motion video revealed that females removed the spermatangia by blowing or eating after picking. These results suggest that picking behaviour is used for sperm removal but not for sperm transfer. Moreover, the frequency of buccal mass elongation was higher in copulated females than in virgin females, consistent with the sequential mate choice theory whereby virgin females secure sperm for fertilisation, while previously copulated females are more selective about their mate. Female I. paradoxus may choose its mate cryptically through postcopulatory picking behaviour

    Adaptive Radiation in Mediterranean Cistus (Cistaceae)

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    lineage consists of 12 species primarily distributed in Mediterranean habitats and is herein subject to analysis. lineages), which display asymmetric characteristics: number of species (2 vs. 10), leaf morphologies (linear vs. linear to ovate), floral characteristics (small, three-sepalled vs. small to large, three- or five-sepalled flowers) and ecological attributes (low-land vs. low-land to mountain environments). A positive phenotype-environment correlation has been detected by historical reconstructions of morphological traits (leaf shape, leaf labdanum content and leaf pubescence). Ecological evidence indicates that modifications of leaf shape and size, coupled with differences in labdanum secretion and pubescence density, appear to be related to success of new species in different Mediterranean habitats.

    Membrane Properties and the Balance between Excitation and Inhibition Control Gamma-Frequency Oscillations Arising from Feedback Inhibition

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    Computational studies as well as in vivo and in vitro results have shown that many cortical neurons fire in a highly irregular manner and at low average firing rates. These patterns seem to persist even when highly rhythmic signals are recorded by local field potential electrodes or other methods that quantify the summed behavior of a local population. Models of the 30–80 Hz gamma rhythm in which network oscillations arise through ‘stochastic synchrony’ capture the variability observed in the spike output of single cells while preserving network-level organization. We extend upon these results by constructing model networks constrained by experimental measurements and using them to probe the effect of biophysical parameters on network-level activity. We find in simulations that gamma-frequency oscillations are enabled by a high level of incoherent synaptic conductance input, similar to the barrage of noisy synaptic input that cortical neurons have been shown to receive in vivo. This incoherent synaptic input increases the emergent network frequency by shortening the time scale of the membrane in excitatory neurons and by reducing the temporal separation between excitation and inhibition due to decreased spike latency in inhibitory neurons. These mechanisms are demonstrated in simulations and in vitro current-clamp and dynamic-clamp experiments. Simulation results further indicate that the membrane potential noise amplitude has a large impact on network frequency and that the balance between excitatory and inhibitory currents controls network stability and sensitivity to external inputs

    Sustained immunogenicity and efficacy of the HPV-16/18 AS04-adjuvanted vaccine up to 8.4 years of follow-up

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    Prophylactic human papillomavirus (HPV) vaccines are now available and vaccination programs are being widely implemented, targeting adolescent girls prior to sexual debut. Since the risk of HPV exposure persists throughout a woman's sexual life, the duration of protection provided by vaccination is critical to the overall vaccine effectiveness. We report the long-term efficacy and immunogenicity of the HPV-16/18 AS04-adjuvanted vaccine (Cervarix (R)) up to 8.4 y after the first vaccine dose. In an initial placebo-controlled study performed in US, Canada and Brazil, women aged 15-25 y with normal cervical cytology, HPV-16/18 seronegative by ELISA, DNA-negative for 14 oncogenic HPV types by PCR, received either the HPV16/18 vaccine or placebo (n = 1,113). Subjects were followed up to 6.4 y after the first dose (n = 776). We report an additional 2-y follow-up for women enrolled from the Brazilian centers from the initial study (n = 436). During the current follow-up study (HPV-023, NCT00518336), no new infection or lesions associated with HPV-16/18 occurred in the vaccine group. Vaccine efficacy over the entire follow-up (up to 8.4 y) was 95.1% (84.6, 99.0) for incident infection, 100% (79.8, 100) for 6-mo persistent infection, 100% (56.1, 100) for 12-mo persistent infection and 100% (< 0, 100) for CIN2+ associated with HPV-16/18. All women in the vaccine group remained seropositive to both HPV-16/18, with antibody titers for total and neutralizing antibodies remaining several-folds above natural infection levels. The safety profile was clinically acceptable for both vaccine and control groups. This is, to date, the longest follow-up study for a licensed cervical cancer vaccine.83GlaxoSmithKline Biological

    Efficacy of a bivalent L1 virus-like particle vaccine in prevention of infection with human papillomavirus types 16 and 18 in young women: a randomised controlled trial

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    Background Vaccination against the most common oncogenic human papillomavirus (HPV) types, HPV-16 and HPV-18, could prevent development of up to 70% of cervical cancers worldwide. We did a randomised, double-blind, controlled trial to assess the efficacy, safety, and immunogenicity of a bivalent HPV-16/18 L1 virus-like particle vaccine for the prevention of incident and persistent infection with these two virus types, associated cervical cytological abnormalities, and precancerous lesions. Methods We randomised 1113 women between 15-25 years of age to receive three doses of either the vaccine formulated with AS04 adjuvant or placebo on a 0 month, 1 month, and 6 month schedule in North America and Brazil. Women were assessed for HPV infection by cervical cytology and self-obtained cervicovaginal samples for up to 27 months, and for vaccine safety and immunogenicity. Findings In the according-to-protocol analyses, vaccine efficacy was 91.6% (95% CI 64.5-98.0) against incident infection and 100% against persistent infection (47.0-100) with HPV-16/18. In the intention-to-treat analyses, vaccine efficacy was 95.1% (63.5-99.3) against persistent cervical infection with HPV-16/18 and 92.9% (70.0-98.3) against cytological abnormalities associated with HPV-16/18 infection. The vaccine was generally safe, well tolerated, and highly immunogenic. Interpretation The bivalent HPV vaccine was efficacious in prevention of incident and persistent cervical infections with HPV-16 and HPV-18, and associated cytological abnormalities and lesions. Vaccination against such infections could substantially reduce incidence of cervical cancer.36494471757176

    Prevalence of Human Papillomavirus Infection and Associated Risk Factors in Young Women in Brazil, Canada, and the United States: A Multicenter Cross-sectional Study

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    To determine the prevalence of cervical human papillomavirus (HPV) infection and risk factors in young women from Brazil, Canada, and the USA. Cross-sectional study in 3204 healthy women, aged 15 to 25 years. Cervical samples were collected for cytology and for HPV DNA detection (SPF(10)-LiPA(25) system). Serum samples were collected for the measurement of HPV-16 and HPV-18 antibodies by enzyme-linked immunosorbent assay. Risk factors were obtained through a questionnaire. Overall, 26.6% of women had DNA detected for at least 1 HPV type. The prevalence for oncogenic HPV types was 21.7% (25% in Brazil, 16.9% in Canada, and 19.1% in the USA). HPV-16 was the most prevalent oncogenic type (5.2%). The next most common oncogenic HPV types were 51 (3.3%), 52 (3.3%), 31 (2.9%), 66 (2.3%), and 39 (2.0%). Multiple oncogenic types were detected in one-third of the infections. The prevalence of HPV-16 and/or HPV-18 infections detected by DNA and/or enzyme-linked immunosorbent assay was 24.8%. The majority of women (85%) had a normal cervical cytology. Sexual behavior was the main determinant for HPV-16/18 infections and squamous intraepithelial lesions. The prevalence of HPV oncogenic infections was high and linked to sexual behavior. Strategies to reduce the burden of oncogenic HPV infection, such as prophylactic vaccination programs, are likely to impact the burden of disease due to cervical precancer and cancer.302173184GlaxoSmithKline Biological
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