1,464 research outputs found
Recommended from our members
Room reflections and constancy in speech-like sounds: within-band effects
The experiment asks whether constancy in hearing precedes or follows grouping. Listeners heard speech-like
sounds comprising 8 auditory-filter shaped noise-bands that had temporal envelopes corresponding to those
arising in these filters when a speech message is played. The „context‟ words in the message were “next you‟ll
get _to click on”, into which a “sir” or “stir” test word was inserted. These test words were from an 11-step
continuum that was formed by amplitude modulation. Listeners identified the test words appropriately and quite
consistently, even though they had the „robotic‟ quality typical of this type of 8-band speech. The speech-like
effects of these sounds appears to be a consequence of auditory grouping. Constancy was assessed by comparing
the influence of room reflections on the test word across conditions where the context had either the same level
of reflections, or where it had a much lower level. Constancy effects were obtained with these 8-band sounds,
but only in „matched‟ conditions, where the room reflections were in the same bands in both the context and the
test word. This was not the case in a comparison „mismatched‟ condition, and here, no constancy effects were
found. It would appear that this type of constancy in hearing precedes the across-channel grouping whose
effects are so apparent in these sounds. This result is discussed in terms of the ubiquity of grouping across
different levels of representation
The Role of Tephra in Enhancing Organic Carbon Preservation in Marine Sediments
Preservation of organic carbon (Corg) in marine sediments plays a major role in defining ocean-atmosphere CO2 levels, Earth climate, and the generation of hydrocarbons. Important controls over sedimentary Corg preservation include; biological productivity, Corg isolation from oxidants (mainly dissolved O2) in the overlying water column and sediments, and Corg – mineral association in sediments. Deposition of the products of explosive volcanism (tephra) in the oceans directly enhances Corg burial through all these mechanisms, and indirectly through enhanced formation of authigenic carbonate (Cauth) derived from sedimentary Corg. In the modern oceans, it is suggested that tephra deposition may account for 5–10% of the Corg burial flux and 10–40% of the Cauth burial flux. However, during certain periods in Earth's history, extensive explosive volcanism may have led to enhanced Cauth precipitation on a sufficiently large scale to influence the global ocean-atmosphere carbon cycle. Changes in tephra-related Corg preservation may also have played a role in increasing Corg preservation rates in local marine basins, at the oxic-anoxic boundary and enhanced the generation of hydrocarbon deposits in these settings
Diagenesis in tephra-rich sediments from the Lesser Antilles Volcanic Arc: Pore fluid constraints
We present sediment pore fluid and sediment solid phase results obtained during IODP Expedition 340 from seven sites located within the Grenada Basin of the southern Lesser Antilles Volcanic Arc region. These sites are generally characterized as being low in organic carbon content and rich in calcium carbonate and volcanogenic material. In addition to the typical reactions related to organic matter diagenesis, pore fluid chemistry indicates that the diagenetic reactions fall within two broad categories; (1) reactions related to chemical exchange with volcanogenic material and (2) reactions related to carbonate dissolution, precipitation, or recrystallization. For locations dominated by reaction with volcanogenic material, these sites exhibit increases in dissolved Ca with coeval decreases in Mg. We interpret this behavior as being driven by sediment-water exchange reactions from the alteration of volcanic material that is dispersed throughout the sediment package, which likely result in formation of Mg-rich secondary authigenic clays. In contrast to this behavior, sediment sequences that exhibit decreases in Ca, Mg, Mn, and Sr with depth suggest that carbonate precipitation is an active diagenetic process affecting solute distributions. The distributions of pore fluid 87Sr /86Sr reflect these competitive diagenetic reactions between volcanic material and carbonate, which are inferred by the major cation distributions. From one site where we have solid phase 87Sr /86Sr (site U1396), the carbonate fraction is found to be generally consistent with the contemporaneous seawater isotope values. However, the 87Sr /86Sr of the non-carbonate fraction ranges from 0.7074 to 0.7052, and these values likely represent a mixture of local arc volcanic sources and trans-Atlantic eolian sources. Even at this site where there is clear evidence for diagenesis of volcanogenic material, carbonate diagenesis appears to buffer pore fluid 87Sr /86Sr from the larger changes that might be expected given the high abundance of tephra in these sediments. Part of this carbonate buffering, at this site as well as throughout the region, derives from the fact that the Sr concentration in the non-carbonate fraction is generally low (< 200 ppm), whereas the carbonate fraction has Sr concentrations approaching ∼1000 ppm
Group formation under limited resources: narrow basin of equality
The formation of groups in competition and the aggressive interactions between them are ubiquitous phenomena in society. These include student activities in the classroom, election races between political parties, and intensifying trade wars between countries. Why do individuals form themselves into groups? What is the optimal size of groups? And how does the group size distribution affect resource allocations? These questions have been the subjects of intense research in economics, political science, sociology, and ethology. In this study, we explore the group-size effects on the formation of groups and resource allocations from an economic standpoint. While being in a large group is generally advantageous in competition, an increase in the management costs would set an upper bound to the individual benefit of members. Under such counteracting size effects, we consider the dynamics of group formation in which people seek a conservative measure to reduce their possible maximum loss. We are especially interested in the effects of group size on social inequalities at both group and individual level in resource allocation. Our findings show that the low positive size-effect and the high negative size-effect result in different types of social inequalities. We conclude, from the relation between the inequality measures and group distributions predicted within the model, that overall social equality only can be achieved within a narrow region where two counteracting size-effects are balanced
The cost of promiscuity: sexual transmission of Nosema microsporidian parasites in polyandrous honey bees
Multiple mating (and insemination) by females with different males, polyandry, is widespread across animals, due to material and/or genetic benefits for females. It reaches particularly high levels in some social insects, in which queens can produce significantly fitter colonies by being polyandrous. It is therefore a paradox that two thirds of eusocial hymenopteran insects appear to be exclusively monandrous, in spite of the fitness benefits that polyandry could provide. One possible cost of polyandry could be sexually transmitted parasites, but evidence for these in social insects is extremely limited. Here we show that two different species of Nosema microsporidian parasites can transmit sexually in the honey bee Apis mellifera. Honey bee males that are infected by the parasite have Nosema spores in their semen, and queens artificially inseminated with either Nosema spores or the semen of Nosema-infected males became infected by the parasite. The emergent and more virulent N. ceranae achieved much higher rates of infection following insemination than did N. apis. The results provide the first quantitative evidence of a sexually transmitted disease (STD) in social insects, indicating that STDs may represent a potential cost of polyandry in social insects
Insect-mediated seed-set evaluation of 21 soybean lines segregating for male sterility at 10 different loci
Age-specific outcomes from the first round of HPV screening in unvaccinated women: Observational study from the English cervical screening pilot
Objective: To report detailed age-specific outcomes from the first round of an English pilot studying the implementation of high-risk human papillomavirus (HR-HPV) testing in primary cervical screening. Design: Observational study with screening in 2013–2016, followed by two early recalls and/or colposcopy until the end of 2019. Setting: Six NHS laboratory sites. Population: A total of 1 341 584 women undergoing screening with HR-HPV testing or liquid-based cytology (LBC). Methods: Early recall tests and colposcopies were recommended, depending on the nature of the screening-detected abnormality. Main outcome measures: We reported standard screening process indicators, e.g. proportions with an abnormality, including high-grade cervical intraepithelial neoplasia (CIN2+) or cancer, and the positive predictive value (PPV) of colposcopy for CIN2+, by screening test and age group. Results: Among unvaccinated women screened with HR-HPV testing at age 24–29 years, 26.9% had a positive test and 10.4% were directly referred to colposcopy following cytology triage, with a PPV for CIN2+ of 47%. At 50–64 years of age, these proportions were much lower: 5.3%, 1.2% and 27%, respectively. The proportions of women testing positive for HR-HPV without cytological abnormalities, whose early recall HR-HPV tests returned negative results, were similar across the age spans: 54% at 24–29 years and 55% at 50–64 years. Two-thirds of infections at any age were linked to non-16/18 genotypes. Among women with CIN2, CIN3 or cervical cancer, however, the proportion of non-16/18 infections increased with age. As expected, the detection of abnormalities was lower following screening with LBC. Conclusions: These data provide a reliable reference for future epidemiological studies, including those concerning the effectiveness of HPV vaccination. Tweetable abstract: Data from the English pilot study provide a comprehensive overview of abnormalities detected through HPV screening
Colony Collapse Disorder: A Descriptive Study
BACKGROUND: Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. METHODS AND PRINCIPAL FINDINGS: Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in control colonies than CCD-affected colonies. CONCLUSIONS/SIGNIFICANCE: This is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted
Monophasic synovial sarcoma presenting as a primary ileal mass: a case report and review of the literature
<p>Abstract</p> <p>Introduction</p> <p>Synovial sarcoma is a rare malignant mesenchymal tumor mainly arising in the peri-articular tissue in young adults. There are few cases reported in other areas.</p> <p>Case presentation</p> <p>We report the case of a 29-year-old Saudi woman of Arabian ethnicity with synovial sarcoma arising primarily from the ileum who presented with abdominal pain, a palpable mass and incomplete intestinal obstruction. A literature review was performed to gather information on this rare gastrointestinal tract sarcoma.</p> <p>Conclusions</p> <p>Although it is a rare tumor of the pre-articular tissues, synovial sarcoma can present, in exceedingly rare cases, in unusual anatomical sites such as the gastrointestinal tract. We believe the reporting of all rare or unexpected presentations of sarcoma will eventually improve our understanding of this relatively unusual malignancy.</p
- …