1,439 research outputs found
Biodiversity's big wet secret: the global distribution of marine biological records reveals chronic under-exploration of the deep pelagic ocean
Background: Understanding the distribution of marine biodiversity is a crucial first step towards the effective and sustainable management of marine ecosystems. Recent efforts to collate location records from marine surveys enable us to assemble a global picture of recorded marine biodiversity. They also effectively highlight gaps in our knowledge of particular marine regions. In particular, the deep pelagic ocean - the largest biome on Earth - is chronically under-represented in global databases of marine biodiversity.
Methodology/Principal Findings: We use data from the Ocean Biogeographic Information System to plot the position in the water column of ca 7 million records of marine species occurrences. Records from relatively shallow waters dominate this global picture of recorded marine biodiversity. In addition, standardising the number of records from regions of the ocean differing in depth reveals that regardless of ocean depth, most records come either from surface waters or the sea bed. Midwater biodiversity is drastically under-represented.
Conclusions/Significance: The deep pelagic ocean is the largest habitat by volume on Earth, yet it remains biodiversity's big wet secret, as it is hugely under-represented in global databases of marine biological records. Given both its value in the provision of a range of ecosystem services, and its vulnerability to threats including overfishing and climate change, there is a pressing need to increase our knowledge of Earth's largest ecosystem
Software Configurable Multichannel Transceiver
Emerging test instrumentation and test scenarios increasingly require network communication to manage complexity. Adapting wireless communication infrastructure to accommodate challenging testing needs can benefit from reconfigurable radio technology. A fundamental requirement for a software-definable radio system is independence from carrier frequencies, one of the radio components that to date has seen only limited progress toward programmability. This paper overviews an ongoing project to validate the viability of a promising chipset that performs conversion of radio frequency (RF) signals directly into digital data for the wireless receiver and, for the transmitter, converts digital data into RF signals. The Software Configurable Multichannel Transceiver (SCMT) enables four transmitters and four receivers in a single unit the size of a commodity disk drive, programmable for any frequency band between 1 MHz and 6 GHz
Optothermal Stability of Large ULE and Zerodur Mirrors
Marshall Space Flight Center's (MSFC) X-ray and Cryogenic Test Facility (XRCF) has tested the optothermal stability of two low-CTE, large-aperture mirrors in a thermal vacuum chamber. The mirrors deformed from several causes such as: thermal gradients, thermal soaks, coefficient of thermal expansion (CTE) gradients, CTE mismatch, and stiction. This paper focuses on how the aforementioned conditions affected the surface figure of the large optics while in vacuum at temperatures ranging from 230 to 310 K (-43 to 37 C). The presented data, conclusions, and taxonomy are useful for designing mirrors and support structures for telescopes. The data is particularly useful for telescopes that require extreme dimensional stability or telescopes that operate at a temperature far from ambient
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Buried shallow fault slip from the South Napa earthquake revealed by near-field geodesy.
Earthquake-related fault slip in the upper hundreds of meters of Earths surface has remained largely unstudied because of challenges measuring deformation in the near field of a fault rupture. We analyze centimeter-scale accuracy mobile laser scanning (MLS) data of deformed vine rows within ±300 m of the principal surface expression of the M (magnitude) 6.0 2014 South Napa earthquake. Rather than assuming surface displacement equivalence to fault slip, we invert the near-field data with a model that allows for, but does not require, the fault to be buried below the surface. The inversion maps the position on a preexisting fault plane of a slip front that terminates ~3 to 25 m below the surface coseismically and within a few hours postseismically. The lack of surface-breaching fault slip is verified by two trenches. We estimate near-surface slip ranging from ~0.5 to 1.25 m. Surface displacement can underestimate fault slip by as much as 30%. This implies that similar biases could be present in short-term geologic slip rates used in seismic hazard analyses. Along strike and downdip, we find deficits in slip: The along-strike deficit is erased after ~1 month by afterslip. We find no evidence of off-fault deformation and conclude that the downdip shallow slip deficit for this event is likely an artifact. As near-field geodetic data rapidly proliferate and will become commonplace, we suggest that analyses of near-surface fault rupture should also use more sophisticated mechanical models and subsurface geomechanical tests
Giving credit when credit is due : improvement initiatives in three diverse school districts to increase on-time graduation
One of the most important measures of success of a high school is its graduation rate. There are many factors that influence whether or not students graduate in the traditional four-year schedule. Student motivation and achievement certainly are primary reasons students may meet this expectation, but oftentimes there are other issues that contribute to the delay of on-time graduation. Sometimes these factors are actually beyond the control of the student. Frequent student mobility, socio-economic disadvantages, and behavioral issues are reasons that often impede on-time graduation for students. Students affected by these issues desperately need schools to be flexible and find options to keep them in school and on course to graduate with their cohort. Of the students who eventually drop out, one-third are behind in their coursework in the 9th grade (Alliance for Excellent Education, 2010)The purpose of this initiative was to examine the impact of student mobility, socio-economic distress, and chronic negative behavior on on-time graduation, as well, evaluate and develop programs and protocols that provide options to help students retain and regain credits needed to graduate with their cohort. This work studied students and personnel in three demographically different high schools in North Carolina: a large, urban school in Cary, NC drawing from an affluent area; a large school located near a military base in Fayetteville, NC; and a small, mountain school serving many students who are socio-economically disadvantaged in Murphy, NC.Data were gathered through the spring, summer, and fall semesters of 2015. The research practitioners investigated data drawn from a variety of credit recovery and retention options, including, a personalized registration program and several on-line programs, such as GradPoint, Study Island, and Edgenuity. One research practitioner also identified effective strategies to create a training program for school counselors to assist students in retaining and regaining credits toward graduation. This qualitative data gives voice to the students who often have no voice when it comes to making decisions when they fall behind their cohort, and provides counselors with the tools to assist these students. Qualitative data were gathered through a variety of research methods, including surveys, interviews, case studies, and focus groups. These methods were selected because of their ability to solicit the thoughts, feelings, and experiences of those participating in the improvement change (Creswell, 2012). The intent of this work was to increase options for students at risk of not graduating on time, thereby improving their chance of staying in school and graduating with their cohort
Octet baryon electromagnetic form factors in nuclear medium
We study the octet baryon electromagnetic form factors in nuclear matter
using the covariant spectator quark model extended to the nuclear matter
regime. The parameters of the model in vacuum are fixed by the study of the
octet baryon electromagnetic form factors. In nuclear matter the changes in
hadron properties are calculated by including the relevant hadron masses and
the modification of the pion-baryon coupling constants calculated in the
quark-meson coupling model. In nuclear matter the magnetic form factors of the
octet baryons are enhanced in the low region, while the electric form
factors show a more rapid variation with . The results are compared with
the modification of the bound proton electromagnetic form factors observed at
Jefferson Lab. In addition, the corresponding changes for the bound neutron are
predicted.Comment: Version accepted for publication in J.Phys. G. Few changes. 40 pages,
14 figures and 8 table
Modeling the Extremely Lightweight Zerodur Mirror (ELZM) Thermal Soak Test
No abstract availabl
Malaria Clusters among Illegal Chinese Immigrants to Europe through Africa
Between November 2002 and March 2003, 17 cases of malaria (1 fatal) were observed in illegal Chinese immigrants who traveled to Italy through Africa. A further cluster of 12 was reported in August, 2002. Several immigrants traveled by air, making the risk of introducing sudden acute respiratory syndrome a possibility should such illegal immigrations continue
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