803 research outputs found
Holocene Vegetation, Climate, and Carbon History on Western Kodiak Island, Alaska
At Phalarope Pond, western Kodiak Island, a multidisciplinary study using pollen and spores, macrofossils, stable isotopes, and carbon accumulation provides the Holocene vegetation and climate history following the deglaciation that began over 16,000 cal years ago (yr BP) [years Before Present, as calibrated from 1950]. Following a cold and dry Younger Dryas, a warm and wet early Holocene was characterized by abundant ferns in a sedge tundra environment with maximum carbon accumulation, similar to high latitude peatlands globally. About 8,700 cal yr BP sedge and ferns declined and climate remained warm as drier conditions prevailed, limiting carbon sequestration. The abrupt shift in D/H (Deuterium/Hydrogen) isotopes of about 60 percent indicates a shift to cooler conditions or a more distal moisture source. Neoglaciation beginning about 3,700 cal yr BP is evident from increases in Artemisia, Empetrum and Betula, signifying cooler conditions, while Alnus declines, paralleling regional trends
Numerical Evaluation of Micro-Pocket Fission Detectors
Micro-pocket fission detectors (MPFDs) are miniature fission chambers suitable for in-core neutron measurement that have been under development at Kansas State University for over one decade. Current-generation devices have been used at a number of university reactors (Kansas State, Wisconsin, and MIT) and as part of the first experiments performed during the recent restart of TREAT. Ongoing research aims to improve understanding of the existing MPFDs and to optimize designs for future deployment. To aid in this development, the dynamic response of a prototypic MPFD was evaluated using Garfield++, Elmer, Gmsh, and Stopping and Range of Ions in Matter (SRIM). Specifically, the finite-element code Elmer was used to calculate the electric field on a mesh generated by Gmsh. SRIM was used to compute the energy loss tables of the fission fragments in the gas. With output from Elmer and SRIM, Garfield++ was used to simulate the ionization process, the resulting electron drift, and the induced signal. This particular Garfield++ application was developed with hybrid parallelization based MPI and OpenMP. The performance of the MPFDs subjected to different temperatures and applied voltages was evaluated. The preliminary results indicate the fission fragment deposits a few MeV of energy in the gas, consistent with previous estimates. The pulses in the MPFDs can be formed in the nanosecond scale, thus accommodating high count rates and, hence, high neutron-flux levels. Ongoing work aims to extend this model and validate it against existing and planned experimental data
Very Shallow Water Bathymetry Retrieval from Hyperspectral Imagery at the Virginia Coast Reserve (VCR\u2707) Multi-Sensor Campaign
A number of institutions, including the Naval Research Laboratory (NRL), have developed look up tables for remote retrieval of bathymetry and in-water optical properties from hyperspectral imagery (HSI) [6]. For bathymetry retrieval, the lower limit is the very shallow water case (here defined as \u3c 2m), a depth zone which is not well resolved by many existing bathymetric LIDAR sensors, such as SHOALS [4]. The ability to rapidly model these shallow water depths from HSI directly has potential benefits for combined HSI/LIDAR systems such as the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) [10]. In this study, we focused on the validation of a near infra-red feature, corresponding to a local minimum in absorption (and therefore a local peak in reflectance), which can be correlated directly to bathymetry with a high degree of confidence. Compared to other VNIR wavelengths, this particular near-IR feature corresponds to a peak in the correlation with depth in this very shallow water regime, and this is a spectral range where reflectance depends primarily on water depth (water absorption) and bottom type, with suspended constituents playing a secondary role
Holocene Vegetation, Climate, and Carbon History on Western Kodiak Island, Alaska
At Phalarope Pond, western Kodiak Island, a multidisciplinary study using pollen and spores, macrofossils, stable isotopes, and carbon accumulation provides the Holocene vegetation and climate history following the deglaciation that began over 16,000 cal years ago (yr BP). Following a cold and dry Younger Dryas, a warm and wet early Holocene was characterized by abundant ferns in a sedge tundra environment with maximum carbon accumulation, similar to high latitude peatlands globally. About 8,700 cal yr BP sedge and ferns declined and climate remained warm as drier conditions prevailed, limiting carbon sequestration. The abrupt shift in D/H isotopes of about 60% indicates a shift to cooler conditions or a more distal moisture source. Neoglaciation beginning about 3,700 cal yr BP is evident from increases in Artemisia, Empetrum and Betula, signifying cooler conditions, while Alnus declines, paralleling regional trends
Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist
Citation: Frese, D. A., Reinhardt, C. D., Bartle, S. J., Rethorst, D. N., Hutcheson, J. P., Nichols, W. T., . . . Thomson, D. U. (2016). Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist. Journal of Animal Science, 94(2), 581-591. doi:10.2527/jas2015-9824Angus crossbred steers (n = 40; 563 +/- 44 kg) were used to examine the effects of handling method and fat thickness on the blood chemistry and physiology of market steers. Steers were blocked by backfat (BF) thickness and were randomly assigned to treatment groups: low-stress handling (LSH) and aggressive handling (AH). Cattle were then ran-domly assigned to one of 5 blocks containing 4 steers from the LSH and AH treatments. Steers in the LSH treatment were walked and AH cattle were run through a course of 1,540 m. Blood samples were obtained via jugular venipuncture before handling (BASE), at 770 m (LAP1), at 1,540 m (LAP2), and at1 h (1H) and 2 h (2H) after finishing the course. Blood samples were analyzed for plasma lactate (LAC), creatinine kinase (CK), base excess (BE), blood pH (pH), serum cortisol (CORT) concentrations, and venous carbon dioxide (PvCO2) and oxygen (PvO2) pressures. Heart rate (HR), respiratory rate (RR), and rectal temperature (TEMP) were measured at the same intervals. Cattle in the AH treatment had greater (P 0.14). Blood pH in AH cattle was decreased compared with that in LSH cattle (P 0.13) at BASE, 1H, or 2H. Heart rate and TEMP were increased in AH cattle compared to LSH (P > 0.01). Serum cortisol was increased (P < 0.05) in AH compared to that in LSH cattle at LAP1 (87.5 vs. 58.9 nmol/ L), LAP2 (144.4 vs. 93.1 nmol/ L), and 1H (113.5 vs. 53.1 nmol/ L). Although RR was not differ-ent between LSH and AH, PvCO2 was decreased in AH compared to that in LSH (P < 0.05) at LAP2 (30.6 vs. 39.3 mmHg) and PvO2 was increased at LAP1 (42.7 vs. 33.5 mmHg) and at LAP2 (51.5 vs. 36.6 mmHg). Lactate was increased in AH cattle in the thicker BF group at 1H (P < 0.05), and blood pH was decreased at LAP1, LAP2, and 1H (P < 0.05) compared to the thinner BF cohorts. Four AH steers became exhausted (EXH) and did not complete the course. Increased CK, decreased PvCO2, and muscle tremors occurred in EXH steers compared to non-exhausted AH cohorts. Results of this study show that AH causes physiologic and blood chemistry changes in steers, which can be potentially detrimental to cattle, emphasizing the need for lowstress handling practices
A Relational Model for Honors Education: From Contagion to Permeability
This article considers the value of honors education beyond its marked contributions to enrollment management goals. Suggesting that quantitative assessments toward understanding the value of honors fail to capture its breadth, interdisciplinary focus, and engagement, authors posit a new way of measuring impacts from “contagion model” (spillover to campus and beyond) to “permeability model” (interface across campus). Pointing to the benefits of permeability for both honors and the broader campus communities, authors encourage practitioners to foster exchange in curricular offerings, spatial inputs, scholarly outputs, extramural funding, and institutional support. The meaning and history of organizational permeability is explored, and examples are provided
Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy Tows and Implications for Composite Structures
This slide presentation reviews the use of Modal Acoustic Emission to monitor damage progression to carbon fiber/epoxy tows. There is a risk for catastrophic failure of composite overwrapped pressure vessels (COPVs) due to burst-before-leak (BBL) stress rupture (SR) failure of carbon-epoxy (C/Ep) COPVs. A lack of quantitative nondestructive evaluation (NDE) is causing problems in current and future spacecraft designs. It is therefore important to develop and demonstrate critical NDE that can be implemented during stages of the design process since the observed rupture can occur with little of no advanced warning. Therefore a program was required to develop quantitative acoustic emission (AE) procedures specific to C/Ep overwraps, but which also have utility for monitoring damage accumulation in composite structure in general, and to lay the groundwork for establishing critical thresholds for accumulated damage in composite structures, such as COPVs, so that precautionary or preemptive engineering steps can be implemented to minimize of obviate the risk of catastrophic failure. A computed Felicity Ratio (FR) coupled with fast Fourier Transform (FFT) frequency analysis shows promise as an analytical pass/fail criterion. The FR analysis and waveform and FFT analysis are reviewe
Comparative effectiveness study of patient‐reported outcomes after proton therapy or intensity‐modulated radiotherapy for prostate cancer
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106701/1/cncr28536.pd
Beyond the Hype: A Real-World Evaluation of the Impact and Cost of Machine Learning-Based Malware Detection
There is a lack of scientific testing of commercially available malware
detectors, especially those that boast accurate classification of
never-before-seen (i.e., zero-day) files using machine learning (ML). The
result is that the efficacy and gaps among the available approaches are opaque,
inhibiting end users from making informed network security decisions and
researchers from targeting gaps in current detectors. In this paper, we present
a scientific evaluation of four market-leading malware detection tools to
assist an organization with two primary questions: (Q1) To what extent do
ML-based tools accurately classify never-before-seen files without sacrificing
detection ability on known files? (Q2) Is it worth purchasing a network-level
malware detector to complement host-based detection? We tested each tool
against 3,536 total files (2,554 or 72% malicious, 982 or 28% benign) including
over 400 zero-day malware, and tested with a variety of file types and
protocols for delivery. We present statistical results on detection time and
accuracy, consider complementary analysis (using multiple tools together), and
provide two novel applications of a recent cost-benefit evaluation procedure by
Iannaconne & Bridges that incorporates all the above metrics into a single
quantifiable cost. While the ML-based tools are more effective at detecting
zero-day files and executables, the signature-based tool may still be an
overall better option. Both network-based tools provide substantial (simulated)
savings when paired with either host tool, yet both show poor detection rates
on protocols other than HTTP or SMTP. Our results show that all four tools have
near-perfect precision but alarmingly low recall, especially on file types
other than executables and office files -- 37% of malware tested, including all
polyglot files, were undetected.Comment: Includes Actionable Takeaways for SOC
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