845 research outputs found

    The digestive morphophysiology of wild, free-living, giraffes

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    We have measured rumen-complex (rumen, reticulum, omasum, abomasum) and intestine (small and large combined) mass in 32 wild giraffes of both sexes with body masses ranging from 289 to 1441 kg, and parotid gland mass, tongue length and mass, masseter and mandible mass in 9 other giraffes ranging in body mass from 181 to 1396 kg. We have estimated metabolic and energy production rates, feed intake and home range size. Interspecific analysis of mature ruminants show that components of the digestive system increase linearly (Mb1) or positively allometric (MbN1)with bodymasswhile variables associatedwith feed intake scalewithmetabolic rate (Mb.75). Conversely, in giraffes ontogenetic increases in rumen-complex masswere negatively allometric (Mbb1), and increases in intestine mass, parotid gland mass, masseter mass, and mandible mass were isometric (Mb1). The relative masseter muscle mass (0.14% of Mb) and the relative parotid mass (0.03% of Mb) are smaller than in other ruminants. Increases in tongue length scale with head length0.72 andMb.32 and tongue mass with Mb.69. Absolute mass of the gastrointestinal tract increased throughout growth but its relative mass declined from 20% to 15% of Mb. Rumen-complex fermentation provides ca 43% of daily energy needs, large intestine fermentation 24% and 33% by digestion of soluble carbohydrates, proteins, and lipids. Dry matter intake (kg) was 2.4% of body mass in juveniles and 1.6% in adults. Energy requirements increased from 35 Mj/day to 190 Mj/day. Browse production rate sustains a core home range of 2.2–11.8 km2.Don Craib Trust and the University of Wyoming.http://www.elsevier.com/locate/cbpa2016-09-30hb201

    Mineral resource information in support of national, regional and local planning : Devon (comprising Devon, Plymouth, Torbay, Dartmoor National Park and part of Exmoor National Park)

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    This report is one of a series prepared by the British Geological Survey for various administrative areas in England for the Office of the Deputy Prime Minister’s research project Mineral Resource Information in Support of National, Regional and Local Planning. The accompanying maps relate to the county of Devon and delineates the mineral resources of current, or potential, economic interest in the area and the sites where minerals are or have been worked. It also relates these to national planning designations, which may represent constraints on the extraction of minerals. Three major elements of information are presented: • the geological distribution and importance of mineral resources; • the extent of mineral planning permissions and the location of current mineral workings; and • the extent of selected, nationally-designated planning constraints. This wide range of information, much of which is scattered and not always available in a consistent and convenient form, is presented on two digitally-generated summary map on the scale of 1:100 000. This scale is convenient for the overall display of the data and allows for a legible topographic base on which to depict the information. However, all the data are held digitally at larger scales using a Geographical Information System (GIS), which allows easy revision, updating and customisation of the information together with its possible integration with other datasets. The information will form part of a Summary of the Mineral Resources of the South West Region. The purpose of the work is to assist all interested parties involved in the preparation and review of development plans, both in relation to the extraction of minerals and the protection of mineral resources from sterilisation. It provides a knowledge base, in a consistent format, on the nature and extent of mineral resources and the environmental constraints, which may affect their extraction. An important objective is to provide baseline data for the long term. The results may also provide a starting point for discussion on specific planning proposals for minerals extraction or on proposals, which may sterilise resources. It is anticipated that the map and report will also provide valuable background data for a much wider audience, including the different sectors of the minerals industry, other agencies and authorities (e.g. The Planning Inspectorate Agency, the Environment Agency, The Countryside Agency and English Nature), environmental interests and the general public. Basic mineral resource information is essential to support mineral exploration and development activities, for resource management and land-use planning, and to establish baseline data for environmental impact studies and environmental guidelines. It also enables a more sustainable pattern and standard of development to be achieved by valuing mineral resources as national assets. The mineral resources covered are sand and gravel, crushed rock aggregate, brick clay, kaolin, ball clay, building stones, hydrocarbons and metalliferous mineralisation

    Cassini nightside observations of the oscillatory motion of Saturn's northern auroral oval

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    In recent years we have benefitted greatly from the first in-orbit multi-wavelength images of Saturn's polar atmosphere from the Cassini spacecraft. Specifically, images obtained from the Cassini UltraViolet Imaging Spectrograph (UVIS) provide an excellent view of the planet's auroral emissions, which in turn give an account of the large-scale magnetosphere-ionosphere coupling and dynamics within the system. However, obtaining near-simultaneous views of the auroral regions with in situ measurements of magnetic field and plasma populations at high latitudes is more difficult to routinely achieve. Here we present an unusual case, during Revolution 99 in January 2009, where UVIS observes the entire northern UV auroral oval during a 2 h interval while Cassini traverses the magnetic flux tubes connecting to the auroral regions near 21 LT, sampling the related magnetic field, particle, and radio and plasma wave signatures. The motion of the auroral oval evident from the UVIS images requires a careful interpretation of the associated latitudinally “oscillating” magnetic field and auroral field-aligned current signatures, whereas previous interpretations have assumed a static current system. Concurrent observations of the auroral hiss (typically generated in regions of downward directed field-aligned current) support this revised interpretation of an oscillating current system. The nature of the motion of the auroral oval evident in the UVIS image sequence, and the simultaneous measured motion of the field-aligned currents (and related plasma boundary) in this interval, is shown to be related to the northern hemisphere magnetosphere oscillation phase. This is in agreement with previous observations of the auroral oval oscillatory motion

    Cassini observations of ionospheric plasma in Saturn's magnetotail lobes

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    Studies of Saturn's magnetosphere with the Cassini mission have established the importance of Enceladus as the dominant mass source for Saturn's magnetosphere. It is well known that the ionosphere is an important mass source at Earth during periods of intense geomagnetic activity, but lesser attention has been dedicated to study the ionospheric mass source at Saturn. In this paper we describe a case study of data from Saturn's magnetotail, when Cassini was located at ? 2200 h Saturn local time at 36 RS from Saturn. During several entries into the magnetotail lobe, tailward flowing cold electrons and a cold ion beam were observed directly adjacent to the plasma sheet and extending deeper into the lobe. The electrons and ions appear to be dispersed, dropping to lower energies with time. The composition of both the plasma sheet and lobe ions show very low fluxes (sometimes zero within measurement error) of water group ions. The magnetic field has a swept-forward configuration which is atypical for this region, and the total magnetic field strength is larger than expected at this distance from the planet. Ultraviolet auroral observations show a dawn brightening, and upstream heliospheric models suggest that the magnetosphere is being compressed by a region of high solar wind ram pressure. We interpret this event as the observation of ionospheric outflow in Saturn's magnetotail. We estimate a number flux between (2.95 ± 0.43) × 109 and (1.43 ± 0.21) × 1010 cm?2 s?1, 1 or about 2 orders of magnitude larger than suggested by steady state MHD models, with a mass source between 1.4 ×102 and 1.1 ×103 kg/s. After considering several configurations for the active atmospheric regions, we consider as most probable the main auroral oval, with associated mass source between 49.7 ±13.4 and 239.8 ±64.8 kg/s for an average auroral oval, and 10 ±4 and 49 ±23 kg/s for the specific auroral oval morphology found during this event. It is not clear how much of this mass is trapped within the magnetosphere and how much is lost to the solar wind

    Orbit orientation and eye morphometrics in giraffes (Giraffa camelopardalis)

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    Giraffe are thought to have excellent vision.We measured eye size, orbit orientation and retina surface area in 27 giraffes of both sexes ranging in age from neonates to mature adults (>10 yrs), to assess how it changes with growth, whether their eye anatomy correlates with their apparently excellent vision and lifestyle, and we have compared our findings with those for other large mammals to assess whether giraffe eye anatomy is unique.We found that giraffe eye volume increases from 33 cm3 at birth to approximately 65 cm3 in adults. The focal (axial) length increases from c. 40 to 48 mm in adults and retina surface area from c. 3000 mm2 at birth to 4320 mm2 in adults. The orbital axis angle at birth is c. 73° and the horizontal visual field mainly monocular and panoramic.With age the axis angle becomes more acute to c. 50° in adults and the visual field more binocular, changes that occur concurrently with increasing neck length. These results show that the giraffe eye and retinal surface area are larger than in all other ungulates, and their visual fields more binocular, attributes which are consistent with the idea that they have excellent vision.The Don Craib Trust (J.D.S.), from a personal research grant (J.D.S.) and the University of Wyoming (G.M.). S.J.v.S. is in receipt of the Maberly Memorial Scholarship and a University of Pretoria study bursary.http://africanzoology.journals.ac.za/am2014mn201

    Cassini multi-instrument assessment of Saturn's polar cap boundary

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    We present the first systematic investigation of the polar cap boundary in Saturn's high-latitude magnetosphere through a multi-instrument assessment of various Cassini in situ data sets gathered between 2006 and 2009. We identify 48 polar cap crossings where the polar cap boundary can be clearly observed in the step in upper cutoff of auroral hiss emissions from the plasma wave data, a sudden increase in electron density, an anisotropy of energetic electrons along the magnetic field, and an increase in incidence of higher-energy electrons from the low-energy electron spectrometer measurements as we move equatorward from the pole. We determine the average level of coincidence of the polar cap boundary identified in the various in situ data sets to be 0.34° ± 0.05° colatitude. The average location of the boundary in the southern (northern) hemisphere is found to be at 15.6° (13.3°) colatitude. In both hemispheres we identify a consistent equatorward offset between the poleward edge of the auroral upward directed field-aligned current region of ~1.5–1.8° colatitude to the corresponding polar cap boundary. We identify atypical observations in the boundary region, including observations of approximately hourly periodicities in the auroral hiss emissions close to the pole. We suggest that the position of the southern polar cap boundary is somewhat ordered by the southern planetary period oscillation phase but that it cannot account for the boundary's full latitudinal variability. We find no clear evidence of any ordering of the northern polar cap boundary location with the northern planetary period magnetic field oscillation phase

    The area-to-mass ratio and fractal dimension of marine flocs

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    publisher: Elsevier articletitle: The area-to-mass ratio and fractal dimension of marine flocs journaltitle: Estuarine, Coastal and Shelf Science articlelink: http://dx.doi.org/10.1016/j.ecss.2017.03.026 content_type: article copyright: © 2017 The Authors. Published by Elsevier Ltd

    Do Neuro-Muscular Adaptations Occur in Endurance-Trained Boys and Men?

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    Most research on the effects of endurance training has focused on endurance training's health-related benefits and metabolic effects in both children and adults. The purpose of this study was to examine the neuromuscular effects of endurance training and to investigate whether they differ in children (9.0-12.9 years) and adults (18.4-35.6 years). Maximal isometric torque, rate of torque development (RTD), rate of muscle activation (Q30), electromechanical delay (EMD), and time to peak torque and peak RTD were determined by isokinetic dynamometry and surface electromyography (EMG) in elbow and knee flexion and extension. The subjects were 12 endurance-trained and 16 untrained boys, and 15 endurance-trained and 20 untrained men. The adults displayed consistently higher peak torque, RTD, and Q30, in both absolute and normalized values, whereas the boys had longer EMD (64.7+/-17.1 vs. 56.6+/-15.4 ms) and time to peak RTD (98.5+/-32.1 vs. 80.4+/-15.0 ms for boys and men, respectively). Q30, normalized for peak EMG amplitude, was the only observed training effect (1.95+/-1.16 vs. 1.10+/-0.67 ms for trained and untrained men, respectively). This effect could not be shown in the boys. The findings show normalized muscle strength and rate of activation to be lower in children compared with adults, regardless of training status. Because the observed higher Q30 values were not matched by corresponding higher performance measures in the trained men, the functional and discriminatory significance of Q30 remains unclear. Endurance training does not appear to affect muscle strength or rate of force development in either men or boys
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