Abstract
We measured hardness, modulus of elasticity, and, for the first time, loss tangent, energy of fracture, abrasion resistance, and impact resistance of zinc- and manganese-enriched materials ...from fangs, stings and other “tools” of an ant, spider, scorpion and nereid worm. The mechanical properties of the Zn- and Mn-materials tended to cluster together between plain and biomineralized “tool” materials, with the hardness reaching, and most abrasion resistance values exceeding, those of calcified salmon teeth and crab claws. Atom probe tomography indicated that Zn was distributed homogeneously on a nanometer scale and likely bound as individual atoms to more than ¼ of the protein residues in ant mandibular teeth. This homogeneity appears to enable sharper, more precisely sculpted “tools” than materials with biomineral inclusions do, and also eliminates interfaces with the inclusions that could be susceptible to fracture. Based on contact mechanics and simplified models, we hypothesize that, relative to plain materials, the higher elastic modulus, hardness and abrasion resistance minimize temporary or permanent tool blunting, resulting in a roughly 2/3 reduction in the force, energy, and muscle mass required to initiate puncture of stiff materials, and even greater force reductions when the cumulative effects of abrasion are considered. We suggest that the sharpness-related force reductions lead to significant energy savings, and can also enable organisms, especially smaller ones, to puncture, cut, and grasp objects that would not be accessible with plain or biomineralized “tools”.
Objective/Background Aorto-bifemoral bypass remains the gold standard for treatment of aortoiliac occlusive disease (AIOD) in patients with advanced (TASC D) lesions, but has significant associated ...morbidity and mortality. Treatment with a unibody stent-graft positioned at the aortic bifurcation is a potential endovascular option for the treatment of AIOD. The current study examines the safety, efficacy, and early patency rates of the Endologix AFX unibody stent-graft for treatment of AIOD. Methods A multicenter retrospective review was conducted of patients treated exclusively for AIOD with the AFX device. Primary, assisted primary, and secondary patency rates were noted. Clinical improvement was assessed using Rutherford classification and ankle brachial index. Mean duration of follow-up was 22.2 ± 11.2 months. Ninety-one patients (56 males 62%) were studied. Results Sixty-seven patients (74%) presented with lifestyle-limiting intermittent claudication and the remaining 24 (26%) had critical limb ischemia. Technical success was 100%. Complications included groin infection ( n = 4 4%), groin hematoma ( n = 4 4%), common iliac rupture ( n = 4 4%), iliac dissection ( n = 4 4%), and thromboembolic event ( n = 3 3%; one femoral, one internal iliac artery, and one internal iliac with bilateral popliteal/tibial thromboemboli). Thirty-day mortality was 1% (1/91) resulting from a case of extensive pelvic thromboembolism. At 1 year, 73% of patients experienced improvement in Rutherford stage of −3 or greater compared with baseline. Nine patients (10%) required 16 secondary interventions. At all time points, primary patency rates were > 90%, assisted patency rates were > 98%, and secondary patency rates were 100%. Conclusion This is the largest study to examine the use of the Endologix AFX unibody stent-graft for the treatment of AIOD. Use of the AFX stent-graft appears to be a safe and effective endovascular treatment for complex AIOD.
Abstract State foresters, state energy biomass contacts, and members of the National Council of Forestry Association Executives were surveyed to gather perceptions on items that should be included in ...a definition of woody biomass. Participants also rated different renewable energies and the particular opportunities and challenges that the utilization of woody biomass faces to become a sustainable energy feedstock. Ninety-seven responses from 43 different states and the District of Columbia suggest that a definition of biomass should not differentiate between naturally regenerated forest stands and plantations or private and public forestlands. There is a lower level of approval for the inclusion of biomass from old-growth or late successional forests and tree needles/leaves in a woody biomass definition. Participants rated the use of combustion as the woody biomass energy platform with the highest potential to become a sustainable source of energy at the state level. There are regional differences in the stated potential of various renewable energy technologies. Some of the greatest opportunities for the use of woody biomass include the generation of locally produced energy and additional work opportunities for harvesters and loggers. Costs of harvesting and transporting biomass material from the field to an energy facility are the greatest challenges facing the development of woody biomass energy initiatives. Any policy effort aimed at promoting wider woody biomass use should consider regional and local resources and social and economic conditions and foster competition among renewable energy platforms.
An interferometric SETI observation of Kepler-111 b Wandia, Kelvin; Garrett, Michael A; Radcliffe, Jack F ...
Monthly notices of the Royal Astronomical Society,
05/2023, Letnik:
522, Številka:
3
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
The application of very long baseline interferometry (VLBI) to the search for extraterrestrial intelligence (SETI) has been limited to date, despite the technique offering many advantages ...over traditional single-dish SETI observations. In order to further develop interferometry for SETI, we used the European VLBI network (EVN) at 21 cm to observe potential secondary phase calibrators in the Kepler field. Unfortunately, no secondary calibrators were detected. However, a VLBA primary calibrator in the field, J1926+4441, offset only ∼1.88 arcmin from a nearby exoplanet Kepler-111 b, was correlated with high temporal $\left(0.25 \, \rm {s}\right)$ and spectral $\left(16384 \times 488\, \rm {Hz \ channels}\right)$ resolution. During the analysis of the high-resolution data, we identified a spectral feature that was present in both the auto and cross-correlation data with a central frequency of 1420.424 ± 0.0002 MHz and a width of 0.25 MHz. We demonstrate that the feature in the cross-correlations is an artefact in the data, associated with a significant increase in each telescope’s noise figure due to the presence of H i in the beam. This would typically go unnoticed in data correlated with standard spectral resolution. We flag (excluded from the subsequent analysis) these channels and phase rotate the data to the location of Kepler-111 b aided by the Gaia catalogue and search for signals with $\rm {SNR}\gt 7$ . At the time of our observations, we detect no transmitters with an equivalent isotropically radiated power ≳4 × 1015 W.
Annual screenings of forage grasses and legumes for shade tolerance were conducted from 1996 to 2001 in the outdoor Shade Tolerance Screening Laboratory at the Horticulture and Agroforestry Research ...Center, University of Missouri. Forty-three forages were grown under non-shade (100% of full sunlight), moderate shade (45%), and dense shade (20%) without competition for water and nutrients. Annual forage yield (g pot
−1
) was equal to or higher under moderate shade for all 43 forages and under dense shade for 31 forages than the non-shade control. Relative distance plasticity index (RDPI), a measure of a species’ adaptability to different environments, ranged from 0.104 to 0.567. Cool season grasses had the lowest RDPI (0.183), followed by warm season grasses (0.252), warm season legumes (0.274), and cool season legumes (0.314), indicating grasses tend to be more shade tolerant than legumes in terms of forage yield. Overall, most grass and legume forages have the potential to produce equivalent or higher yields in agroforestry practices featuring light to moderate shade than forages in open pastures when competition from tree roots is minimized.
Waterborne toxoplasmosis, Brazil, from field to gene de Moura, Lenildo; Bahia-Oliveira, Lilian Marcia Garcia; Wada, Marcelo Y ...
Emerging infectious diseases,
02/2006, Letnik:
12, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Water was the suspected vehicle of Toxoplasma gondii dissemination in a toxoplasmosis outbreak in Brazil. A case-control study and geographic mapping of cases were performed. T. gondii was isolated ...directly from the implicated water and genotyped as SAG 2 type I.
A new habitat for hominoid emergence?The hominoid lineage underwent a major morphological change in the Miocene, acquiring strong hind legs and a more upright posture. The prevailing hypothesis ...pertaining to these changes has been that they were adaptive for foraging on fruit in the terminal branches of tropical forest trees. A pair of papers now argue that, instead, such changes may have been driven by adaptation to feeding on leaves in seasonally dry and open forests. Peppe et al. used new data from fossil mammal study sites and found that the expansion of grassy biomes dominated by grasses with the C4 photosynthetic pathway in eastern Africa likely occurred more than 10 million years earlier than prior estimates. MacLatchy et al. looked at fossils of the earliest ape in this region at this time, Morotopithecus, and found isotope evidence of the consumption of water-stressed vegetation and postcranial morphology indicative of strong hind limbs similar to modern apes. Together, these papers suggest that early hominoids emerged in a dryer and more irregular environment than was previously believed. —BEL and SNV
A sound multi-species vegetation buffer design should incorporate the species that facilitate rapid degradation and sequestration of deposited herbicides in the buffer. A field lysimeter study with ...six different ground covers (bare ground, orchardgrass, tall fescue, timothy, smooth bromegrass, and switchgrass) was established to assess the bioremediation capacity of five forage species to enhance atrazine (ATR) dissipation in the environment via plant uptake and degradation and detoxification in the rhizosphere. Results suggested that the majority of the applied ATR remained in the soil and only a relatively small fraction of herbicide leached to leachates (<15%) or was taken up by plants (<4%). Biological degradation or chemical hydroxylation of soil ATR was enhanced by 20 to 45% in forage treatment compared with the control. Of the ATR residues remaining in soil, switchgrass degraded more than 80% to less toxic metabolites, with 47% of these residues converted to the less mobile hydroxylated metabolites 25 d after application. The strong correlation between the degradation of N-dealkylated ATR metabolites and the increased microbial biomass carbon in forage treatments suggested that enhanced biological degradation in the rhizosphere was facilitated by the forages. Hydroxylated ATR degradation products were the predominant ATR metabolites in the tissues of switchgrass and tall fescue. In contrast, the N-dealkylated metabolites were the major degradation products found in the other cool-season species. The difference in metabolite patterns between the warm- and cool-season species demonstrated their contrasting detoxification mechanisms, which also related to their tolerance to ATR exposure. Based on this study, switchgrass is recommended for use in riparian buffers designed to reduce ATR toxicity and mobility due to its high tolerance and strong degradation capacity.
From a series of shade tolerance screening trials conducted in an outdoor Shade Tolerance Screening Laboratory, 22 forages (16 grasses and 6 legumes) were selected for quality evaluation. The forages ...were grown under non-shade (100% of full sun, the control), moderate shade (45%), and dense shade (20%) with adequate water and nutrients and free of competition from other plants. All 22 forages had equal or higher percent crude protein (%CP) and CP yield (g pot
−1
) under moderate shade than in the control. Under dense shade, 22 and 18 forages had equal or higher %CP and CP yield than in the control, respectively. Under moderate and dense shade, 14 and 15 forages, respectively, maintained relative feed value (RFV) equal to that in the control. Legumes had higher %CP and RFV than grasses with no differences for CP yield. Relative distance plasticity index (RDPI), an indicator of a species’ adaptability to different environments, suggested grasses maintained RFV better than legumes under shade, while legumes were more resilient under shade in maintaining %CP than grasses. Our results suggest most grass and legume forages will maintain or have improved quality when grown in agroforestry practices with light to moderate shade compared to forages grown in open pastures.
The assembly of Africa's iconic C
grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C
grasses are thought to have become ecologically ...dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C
biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C
grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C
grass-dominated habitats in Africa-and globally-by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution.
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