bluuebunny/crossref_metadata_2025 huggingface dataset:
Stochastic perturbation of divide position
Authors: Hindmarsh R. G. A.
Published: September 2017

Perturbation of divide position is considered by a linearization about the Vialov–Nye solution and also about related solutions with O(1) relief. Relaxation times of one-sixteenth the fundamental thickness/accumulation-rate time-scale are found for the Vialov–Nye configuration, while substantial basal topography can halve the rate of relaxation. Steady divide position is most sensitive to anti-symmetric accumulation-rate distributions near the divide, but transient divide motion is most strongly excited by anti-symmetric accumulation rate variations halfway between the margin and the divide. Relaxation times for the Antarctic Peninsula divide position are estimated to be around 200 years, while the larger Greenland ice sheet has a divide-position relaxation time of around 600 years.

Modelling accumulation rate as a white-noise process permits analysis of divide perturbation as a (stochastic) Ornstein–Uhlenbeck process, where the standard deviation of the response is proportional to the standard deviation of the forcing. If observed accumulation-rate variability in the Antarctic Peninsula were anti-symmetric about the divide, it would be sufficient to force the divide position to fluctuate with standard deviation 10–20 times the depth of the ice sheet. There appears to be sufficient noise to cause Raymond bumps to be spread significantly. More data on the statistical variation of accumulation with position are needed. Random forcing will increase the complexity of any fold structures created in the divide region and in particular the number of such structures intersecting any borehole.
Modeling heat, mass, and species transport in polar firn
Authors: Albert Mary R.
Published: September 2017

A finite-element model for simulating multi-dimensional air flow with heat, mass and chemical species transport through firn is discussed. The model is applied to an investigation of near-surface layering effects on ventilation rates. Field measurements of permeability at Summit, Greenland, are presented that show that permeability varies by at least a factor of 10 over the top 3 m, with the surface windpack having much lower permeability, in general, than the underlying firn. The effect of a lower-permeability surface layer is to decrease the air flow in the underlying firn, yet there is still sufficient air flow in the top meters of the firn so that ventilation must be considered for species transport. Channeling, or increased air flow in a layer overlain by a less-permeable layer, can occur even if the microstructure of each layer is isotropic. Conventional estimates of chemical transport due to diffusion alone are likely to underestimate transport, while estimates of ventilation that consider the firn as a homogeneous half-space may overestimate ventilation effects at the near-surface. Effects of firn layering are important for ventilation and must be considered for accurate assessment of firn–air transport mechanisms.
Characteristics of the lower ablation zone of the West Greenland ice sheet for energy-balance modelling
Authors: van den Broeke Michiel
Published: September 2017

In this paper, we present the summer-time energy balance for a site in the lower ablation zone of the West Greenland ice sheet. The summer climate of this part of Greenland is sunny and dry. The energy that is available for melting (on average 174 W m−2 or 4.5 cm w.e.d−1) is mainly provided by net global radiation two-thirds and sensible-heat flux (one-third). The contribution of the sub-surface heat flux, the latent-heat flux and the net longwave radiation to the energy balance are small. We tested some parameterizations to calculate energy-balance components that are currently used in general circulation models, energy-balance models and mesoscale meteorological models. For the area and time period under consideration, parameterizations that use screen-level temperature for the calculation of incoming longwave radiation systematically underestimate this quantity by 10 W m−2 owing to the proximity of the melting-ice surface that restricts temperature increase of the lowest air layers. The incoming global radiation was predicted correctly. Simple explicit schemes that calculate the stability corrections for turbulent fluxes as a function of the bulk Richardson number tend to underestimate the turbulent fluxes by 15 W m−2. The aerodynamic roughness length z0 derived from wind-speed profiles appears to be erroneously small, leading to underestimation of the fluxes by 30 W m−2. Probably, the wind profile is distorted by the rough terrain. An estimate of z0 biased on microtopographical survey yielded a more realistic result. Because all errors work in the same direction, the use of some of the parameterizations can cause serious underestimation of the melting energy.
Basal temperature conditions of the Greenland ice sheet during the glacial cycles
Authors: Huybrechts Philippe
Published: September 2017

A high-resolution, three-dimensional thermomechanical ice-sheet model, which includes isostasy, the possibility of ice-sheet expansion on the continental shelf and refined climatic parameterizations, was used to investigate the basal thermal regime of the Greenland ice sheet. The thermodynamic calculations take into account the usual terms of heat flow within the ice, a thermally active bedrock layer and all of the effects associated with changes in ice thickness and flow pattern. Basal temperature conditions are documented with respect to glacial–interracial shifts in climatic boundary conditions, both in steady state as during simulations over the last two glacial cycles using the GRIP δ180 record. It is found that the basal temperature field shows a large sensitivity in steady-state experiments but that, during a glacial cycle, basal temperature variations are strongly damped, in particular in central areas. A comparison has been made with measured data from deep ice cores and the implications are discussed.
Numerical modelling of a fast-flowing outlet glacier: experiments with different basal conditions
Authors: Pattyn Frank
Published: September 2017

Recent observations in Shirase Drainage Basin. Enderby Land, Antarctica, show that the ice sheet is thinning at the considerable rate of 0.5–1.0 m a −1. Surface velocities in the stream area reach more than 2000 ma−1, making Shirase Glacier one of the fastest-flowing glaciers in East Antarctica. A numerical investigation of the present stress field in Shirase Glacier shows the existence of a large transition zone 200 km in length where both shearing and stretching are of equal importance, followed by a stream zone of approximately 50 km, where stretching is the major deformation process.

In order to improve insight into the present transient behaviour of the ice-sheet system, a two-dimensional time-dependent flowline model has been developed, taking into account the ice-stream mechanics. Both bedrock adjustment and ice temperature are taken into account and the temperature field is fully coupled to the ice-sheet velocity field.

Experiments were carried out with different basal motion conditions in order to understand their influence on the dynamic behaviour of the ice sheet and the stream area in particular. Results revealed that when basal motion becomes the dominant deformation process, (partial) disintegration of the ice sheet is counteracted by colder basal-ice temperatures due to higher advection rates. This gives rise to a cyclic behaviour in ice-sheets response and large changes in local imbalance values.
Heinrich-scale surge oscillations as an internal property of ice sheets
Authors: Saltzman Barry , Verbitsky Mikhail Ya.
Published: September 2017

A dynamical model governing the variations of ice-sheet volume, basal-water amount and ice-surge flux has been formulated in its simplest form, based on fundamental thermomechanical properties of ice sheets governing the basal-melting process. This model includes the effects of the geothermal flux, internal thermal advection and basal friction, the latter two factors being particularly important in regulating the bottom temperature and bringing it to the melting point, i.e. to a state vulnerable to catastrophic ice surges. It is shown that, for certain values of the unknown rate constants, such a model can exhibit oscillations on roughly the same scale as observed Heinrich events, even when external climatic changes are neglected, which would support the view that such events are an internal properly of ice sheets.
Constraints on holocene ice-thickness changes in central Greenland from the GISP2 ice-core data
Authors: Bolzan J. F. , Waddington E. D. , Alley R.B. , Meese D.A.
Published: September 2017

The depth–age relation observed in the GISP2 ice core is the result of the integrated effects of ice-sheet changes over time, as well as the accumulation-rate history. Here, we construct a forward model to compute ages at various depths in the core. In the model, these ages are functions of parameters that describe the ice thickness as a function of time. Using the maximum-likelihood inverse method, these parameters are iteratively adjusted until measured and computed ages agree satisfactorily. The results suggest that the thickness along the flowline connecting the GISP2 and GRIP drill sites has not changed significantly since the onset of the Holocene. We also derive bounds on the likely thickness changes. Because these bounds are independent of assumptions concerning the processes driving the ice-sheet evolution, they can provide useful constraints for other ice-sheet modeling efforts.
Sub-surface melting in blue-ice fields in Dronning Maud Land, Antarctica: observations and modelling
Authors: Bøggild Carl Egede , Winther Jan-Gunnar , Sand Knut , Elvehøy Hallgeir
Published: September 2017

During the Norwegian Antarctic Research Expedition 1993/94, field studies were conducted on a blue-ice field in Jutulgryta, Dronning Maud Land. Measurements of sub-surface temperatures revealed that temperatures in blue ice were about 6°C higher than in the adjacent snow. Despite the predominantly negative air temperatures, a sub-surface melt layer was discovered within the uppermost metre of the blue ice. Here the temperature maximum was consistent throughout the entire month of observations, and resulted in both internal melt and water transport. The melting is a consequence of solar radiative penetration and absorption within the ice, i.e. the “solid-state greenhouse”. Sensitivity experiments using a non-stationary combined radiative and thermodynamic model reveal that the physical properties (here extinction coefficient, radiation transmittance and albedo) strongly control the formation and vertical extent of the melt layer. The persistence of the sub-surface melt layer increases the runoff volume from blue-ice fields, which otherwise might be restricted to a few yearly events when air temperatures reach or exceed the freezing point. The conditions required for melting activity are marginal in Jutulgryta. Hence, this phenomenon may serve as an indicator of climate fluctuations in the area.
A 340 year record of biogenic sulphur from the Weddell Sea area, Antarctica
Authors: Pasteur E. C. , Mulvaney R. , Peel D. A. , Saltzman E. S. , Whung P-Y
Published: September 2017

Detailed records of methanesulphonic acid (MSA) and non-sea-salt sulphate (nss SO42−) have been obtained from ice cores drilled on Dolleman Island on the east coast of the Antarctic Peninsula (70°35.2′S, 60°55.5′W). Annual average concentrations of MSA are presented for the period 1652–1992. Over this time span, the mean annual concentration of MSA is 0.69 μeq l−1 (σ = 0.33, n = 340), the range is 0.13–2.35μeq l−1, and the MSA/nss-SO42− ratio is 0.22. The high MSA concentration reflects the proximity of the Weddell Sea, believed to be a region of high marine phytoplankton production. The overall mean nss-SO42− concentration is about 66% of the total sulphate deposited in the snowfall. Low-frequency variations of MSA and oxygen-isotope signals correlate closely, indicating that they may be modulated by similar atmospheric processes. Positive correlations are observed between the oxygen-isotope signature and both MSA (r = 0.41) and nss SO42− (r = 0.50), significant at the 99% level. A small negative correlation can be seen between both species and the annual duration of sea ice at Scotia Bay, Laurie Island in the South Orkneys, since 1902 (MSA r= –0.23, and nss SO42–r = –0.29; significant at 95% confidence). No significant link between high MSA concentrations and El Niño events is observed at this location.
Recent ice-core climate records from the Cordillera Blanca, Peru
Authors: Davis M. E. , Thompson L. G. , Mosley-Thompson E. , Lin P. N. , Mikhalenko V. N. , Dai J.
Published: September 2017

Ice cores recently drilled to bedrock on the col of Huascarán (9°06′ S, 77°36′ W, 6047 m a.s.l.) offer the potential for a long, annually resolved climate record from tropical South America. This paper presents the record from 1950 to 1993 preserved in microparticle and nitrate concentrations and oxygen-isotopic ratios. Average monthly temperatures from a satellite-linked automatic weather station installed on nearby Hualcán in 1991 are presented. Annual temperatures from local high-altitude meteorological stations, along with the annual Huascarán isotopic record, show a warming trend over the last two decades. The marked preservation of the climate record in oxygen-isotopic ratios on Huascarán is absent at lower-elevation sites, which have been affected by the recent warming. This paper demonstrates the establishment of a time-scale for the Huascarán core, the preservation of the climatic signal with depth and the linkage of the ice-core “proxy-climate” parameters with measured climatic variations.
“Little Ice Age” glaciers in Kamchatka, northeastern Russia
Authors: Solomina O. N. , Muravyev Ya.D. , Bazanova L. I.
Published: September 2017

Lichenometry was used to date “Little Ice Age” moraines in the Kamchatka peninsula, northeastern Russia. The Rhizocarpon geographicum growth-rate curve was based on seven data points from lava flows and moraines, dated using historical records or tephrochronology (15–300 BP). No reduction in growth rate due to decreasing lichen age was observed, so a linear approximation was used. Accuracy test results yield differences between real and calculated dates up to, but not exceeding, five years. From eight “Little Ice Age” (LIA) moraines it was established that Kamchatka glaciers advanced in the 1690s, 1850–70 and 1910–20. Only one moraine clearly corresponded to the 1690s advance. The maximum stage of the LIA was during the mid- to late 19th century when glacier fronts were generally 100–200 m lower than at present. Glacier termini with ash and moraine layers, covered by lichens and vascular plants, have been preserved for 150–300 years, judging by the lichen sizes.
Glaciological observations of Brúarjökull, Iceland, using synthetic aperture radar and thematic mapper satellite data
Authors: Hall Dorothy K. , Williams Richard S. , Sigurdsson Oddur
Published: September 2017

The first European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) images offer opportunities for studying glacier surface properties and near-surface features. Analysis of back-scatter values from digital SAR data from 18 January, 7 June, 1 September and 25 October 1993 of Brúarjökull, an outlet glacier on the northeastern margin of the Vatnajökull ice cap, Iceland, that has a history of episodic surges, reveals several back-scatter boundaries that may relate to glacier facies and, inferentially, to mass balance. For example, a strong back-scatter boundary on the 18 January image of the snow-covered glacier, representing a back-scatter coefficient, σ°, difference of 4.34dB, appears to coincide with the position of the transient snow line at the end of the 1990–91 budget year. The boundary is visible on the 7 September 1991 Landsat thematic mapper (TM) image. The terminus is very difficult to define because of back-wasting from the last surge (1963–64) but is most easily delineated on the 1 September 1993 SAR and the 7 September 1991 TM images, in part due to the presence of ice-margin lakes.
Glaciar Upsala, Patagonia: rapid calving retreat in fresh water
Authors: Warren Charles R. , Greene Debbie R. , Glasser Neil F.
Published: September 2017

The calving rates and calving styles of temperate glaciers that calve into fresh water are distinctively different from those of temperate tide-water glaciers. These contrasts are important for interpreting and predicting the response of ice masses to climate change. Glaciar Upsala is a large calving outlet of Hielo Patagónico Sur (southern Patagonia ice field). Its twentieth-century retreat has been climate-driven but significantly modulated by calving dynamics and by the transition from melting to calving at its eastern terminus. Here, the onset of rapid calving in the early 1980s initiated retreat at ≤440 m a−1. The 1992–93 calving rate (vc) is estimated to be 60 m a−1 in a mean water depth (hw) of 67 m. A vc/hw relationship for fresh water based on 14 sites around the world, including seven deep-water sites, confirms both the linear dependency of vc on hw and the contrast between calving rates in tide water and fresh water. As yet, no physical explanation for this contrast exists, but differences in subaqueous melt rates, longitudinal strain rates and crevassing may provide a partial explanation.
On the effect of sea-ice dynamics on oceanic thermohaline circulation
Authors: Hibler W. D. , Zhang Jinlun
Published: September 2017

An idealized planetary flat-bottom geostrophic ice–ocean model is constructed with boundaries at latitudes 5° and 65° N and longitudes 50° W and 10° E in order to approximate the North Atlantic. The model is driven by fixed zonally averaged wind, surface air temperatures and surface ocean salinity. A dynamic thermodynamic sea-ice model is coupled to the ocean model. Only the thermodynamic insulating effects of the sea ice are considered, and no salt fluxes due to melting and freezing are included. Four equilibrium simulations of about 5000 years each are performed: two with interactive sea ice with and without ice dynamics, and two control simulations with either a fixed or no ice cover.

In the two simulations including interactive sea ice, characteristic oscillations in the ice thickness and ocean temperature are found to occur. The oscillations are smaller when sea-ice dynamics are included. The dominant oscillation occurs at about a 5 year period, with the key feature being that the presence of sea ice tends to insulate the ocean and hence allows an oceanic warming. This warming in turn eventually causes a melt-back of the ice and a subsequent cool-down of the ocean. Oscillations at longer periods of about 20 years in the thermohaline circulation are also observed. These longer-period oscillations are particularly pronounced in the northward surface water transport.
Physical Characteristics and Life Expectancy of Tabular Antarctic Icebergs
Authors: Orheim Olav
Published: September 2017

The Norwegian Antarctic Research Expedition 1978-79 landed on 24 tabular icebergs and flew over many others in the South Atlantic and the Weddell Sea between latitudes 54 and 76°S. Data were obtained on surface mass balance, stratigraphy, density, 10 m temperatures, crevassing, distribution, and age. Ice thicknesses were measured by airborne radio echo-sounding.

All icebergs had experienced surface melting. However, on icebergs south of 66°S., the annual surface melting was only a few centimetres of water equivalent. The average surface mass balance was near zero. Typically the 10 m temperature had increased from about -20° C at the time of calving to -10° C. Only icebergs that had moved northwards from the continent into the west wind drift had snow temperatures close to 0° C. Internal temperatures are increased mainly by the refreezing of percolating melt and rain water. This increased the densities of the upper layers by 100 to 150 kg m-3 above those of nearby ice shelves.

All icebergs measured by radio echo-sounding showed variations in thickness of about 20% of the mean thickness. Nearly all had a convex profile across the short axis and were tilted. An average thickness/freeboard curve indicates that icebergs less than 225 m thick will have permeable layers below sea-level. The ratio of freeboard to thickness varied from 0.21 for a 100 m thick berg to 0.14 for a 350 m thick iceberg.

All icebergs showed systematic surface crevassing parallel with their sides, the crevasse intensity decreasing with distance from the edge. Icebergs with their smallest dimension greater than 400 m usually had a central zone with little crevassing. Grounded icebergs showed severe crevassing, and could not thereafter survive long periods in open water. Bottom crevasses were not detected.
The use of Catastrophe Theory to Analyse the Stability and Toppling of Icebergs
Authors: Nye J. F. , Potter J. R.
Published: September 2017

As an iceberg melts, the resulting change of shape can cause it to list gradually or to become unstable and topple over suddenly. Similarly, when an iceberg breaks up some of the individual pieces may capsize. We have used Zeeman’s analysis of the stability of ships, which is based on catastrophe theory, to examine this problem. We deal only with statical equilibrium; dynamical effects induced by water motion are important for ships, but very large icebergs have correspondingly small oscillations and therefore dynamical aspects are ignored in this first study. The advantage of the catastrophe-theory approach over the conventional stability theory used by naval architects lies in the conceptual clarity that it provides. In particular, it gives a three-dimensional geometrical picture that enables one to see all the possible equilibrium attitudes of a given iceberg, whether they are stable or unstable, whether a stable attitude is dangerously close to an unstable one, and how positions of stable equilibrium can be destroyed as the shape of the iceberg evolves with time.

By making two-dimensional computations we examine the stability of two different shapes of cross-section, rectangles and trapezia, with realistic density distributions. These shapes may list gradually or topple suddenly as a single parameter is changed. For example, we find that a conversion of the vertical sides of a rectangular section into the slightly inward-sloping sides of a trapezium has a comparatively large adverse effect on stability. The main purpose of this work is to suggest how the stability characteristics of any selected iceberg may be investigated systematically.
Comments on Southern Ocean Near-Surface Circulation and its Variability
Authors: Gordon Arnold L.
Published: September 2017

This literature review discusses the mean and variable surface-layer circulation of the Southern Ocean. The variable components are equal to or even more energetic than the mean circulation. Therefore circulation charts often do not present the significant currents that exist during specific periods.
Investigations on the Currents Influencing Iceberg Motion
Authors: Dhalluin M.
Published: September 2017

Several factors contribute to the natural drift of an iceberg, and among these, currents play an important part on the translation and rotation. Some information exists on surface currents in sub-Antarctic areas, but an iceberg behaves as a current integrator due to its draught and it is assumed to drift under the action of a “mean” current. In order to measure the mean current, five drogued buoys were launched in July–August 1979. These buoys were located by Argos satellite transponders. The drift of the buoys gives the mean current from 0 to 230 m depth in the Southern Ocean. Some corrections must be made on the measured drifting speed of the drogued buoys, due to the influence of the wind on the above-water portion of the buoys.
Design Parameters for a South African Iceberg Power and Water Project
Authors: DeMarle David J.
Published: September 2017

Construction of an iceberg processing plant at Saldanha Bay, Republic, of South Africa, is proposed. A reservoir would be constructed at Rieibaai for ice storage. Tidal forces would be harnessed to pump the warm water of Saldanha Lagoon over heat exchangers (using ammonia or propane gas as a heat exchange medium), thus providing power for electrical generators and for melting ice. A functional analysis of operations is presented, together with proposed costs. It is suggested that the fresh water and electricity produced by this system will cost 6¢/m3 and 3¢/kwH, respectively.
Glaciological Investigations Using the Synthetic Aperture Radar Imaging System
Authors: Bindschadler R.A. , Jezek K.C. , Crawford J.
Published: September 2017

Numerous examples of synthetic aperture radar (SAR) imagery of ice sheets are shown and prominent features of glaciological importance which appear in the images are discussed. Features which can be identified include surface undulations, ice-flow lines, crevasses, icebergs, lakes, and streams (even lakes and streams which are inactive or covered by snow), and possibly, the extent of the ablation and wet snow zones. SAR images presented here include both L-band data from the Seasat satellite and X-band data from an airborne radar. These two data sets overlap at a part of eastern Greenland where a direct comparison can be made between two images. Comparison is also made between SAR and Landsat images in western Greenland. It is concluded that SAR and Landsat are highly complementary instruments; Landsat images contain minimal distortion while SAR’s all-weather, day/night capability plus its ability to penetrate snow provide glaciologists with an additional and very powerful tool for research.
Stagnant Ice at the Bed of White Glacier, Axel Heiberg Island. N.W.T., Canada
Authors: Blatter Heinz
Published: September 2017

A total of 400 soundings along 15 profiles were obtained on White Glacier, Axel Heiberg Island, N.W.T. with a monopulse radar equipment that was rebuilt according to a model of the US Geological Survey. The resulting data allowed maps to be compiled of the ice thickness for the glacier tongue, The radio echo-sounding data and englacial temperature measurements give some indication of the existence of stagnant ice in depressions of the glacier bed in the accumulation zone of White Glacier.
Nimbus-7 SMMR Derived Global Snow Cover Parameters
Authors: Chang A.T.C. , Foster J.L. , Hall D.K.
Published: September 2017

Snow covers about 40 million km2 of the land area of the Northern Hemisphere during the winter season. The accumulation and depletion of snow is dynamically coupled with global hydrological and climatological processes. Snow covered area and snow water equivalent are two essential measurements. Snow cover maps are produced routinely by the National Environmental Satellite Data and Information Service of the National Oceanic and Atmospheric Administration (NOAA/NESDIS) and by the US Air Force Global Weather Center (USAFGWC). The snow covered area reported by these two groups sometimes differs by several million km2, Preliminary analysis is performed to evaluate the accuracy of these products.

Microwave radiation penetrating through clouds and snowpacks could provide depth and water equivalent information about snow fields. Based on theoretical calculations, snow covered area and snow water equivalent retrieval algorithms have been developed. Snow cover maps for the Northern Hemisphere have been derived from Nimbus-7 SMMR data for a period of six years (1978–1984). Intercomparisons of SMMR, NOAA/NESDIS and USAFGWC snow maps have been conducted to evaluate and assess the accuracy of SMMR derived snow maps. The total snow covered area derived from SMMR is usually about 10% less than the other two products. This is because passive microwave sensors cannot detect shallow, dry snow which is less than 5 cm in depth. The major geographic regions in which the differences among these three products are the greatest are in central Asia and western China. Future study is required to determine the absolute accuracy of each product.

Preliminary snow water equivalent maps have also been produced. Comparisons are made between retrieved snow water equivalent over large area and available snow depth measurements. The results of the comparisons are good for uniform snow covered areas, such as the Canadian high plains and the Russian steppes. Heavily forested and mountainous areas tend to mask out the microwave snow signatures and thus comparisons with measured water equivalent are poorer in those areas.
DETECTION OF SPECIFIC CAUSES OF TUBERCULOSIS IN THE DAIRY CATTLE OF BANGLADESH AGRICULTURAL UNIVERSITY BY SEQUENCING AND SEQUENCE ANALYSIS
Authors: Yasmin A. , Hossain M. Z. , Rima U. K. , Ruba T. , Khan M. A. H. N. A.
Published: September 2017

Tuberculosis (TB) is a chronic disease of man and animal. In this study intradermal tuberculin test, necropsy, histopathology, polymerase chain reaction (PCR) and sequencing techniques were used to diagnose specific cause of TB in dairy cattle of Bangladesh Agricultural University, Mymensingh. Intradermal tuberculin tests were carried out on randomly selected 100 dairy cattle. Tuberculin test positive cattle (N=05) were examined at necropsy and granulomas in lungs was seen in three cattle. Caseous necrosis and swelling of lymphnodes was seen in prescapular (N=01) and mesenteric (N=02) lymphnodes. In a case nodular lesion was seen in lungs and mesenteric lymphnodes. Portion of infected lungs and lymphnodes were snap frozen, extracted genomic DNA and PCR protocols was adapted targeting MPB83 gene. Result of PCR showed amplification of 600bp fragments in five cases. The MPB83 gene although specific for M. Bovis, the gene is less abundantly expressed by M. tuberculosis. To differentiate infectivity due to M. Bovis and M. Tuberculosis, two more PCR were adapted targeting pncA and oxyR genes. Out of five cattle tested in PCR all samples generated pncA specific 185bp and oxyR gene specific 270bp amplicons. The sequencing of MPB83, pncA and oxyR genes were carried out. Results of sequencing did not show mutation in MPB83 gene. Sequencing of pncA gene showed replacement of nucleic acid base (guanine to cytosin) in position 169 in cattle no. 5. Similarly, sequence analysis of oxyR gene (n=05) showed replacement of nucleic acid base (adenine to guanine) in position 285 in cattle no. 5. The cattle no. 5 was confirmedly infected with M. Tuberculosis and rest of the cattle were infected with M. Bovis. The tuberculin tests, necropsy, histopathology and PCR amplification of MPB83 gene may not contribute species specific detection of Mycobacterial infectivity in cattle. Sequencing and sequence analysis of pncA and oxyR genes found to differentiate infectivity in cattle due to M. Bovis and M. Tuberculosis.  Both of the bacterial species are extremely zoonotic and dairy cattle of Bangladesh Agricultural University were infected with both M. Bovis and M. Tuberculosis. It needs to tests all the dairy cattle twice in a year with tuberculin tests and dispose test reactors in order to minimize zoonotic risk.
PREVALENCE OF SUB-CLINICAL MASTITIS AT BANARIPARA UPAZILLA, BARISAL
Authors: Biswas D. , Sarker T.
Published: September 2017

A study was aimed to determine the prevalence of sub-clinical mastitis and also determine the other risk factors that intensify this condition. Prescribed questionnaire was used to take baseline information of the animals and farms and California mastitis test kit was used to determine the SCM in lactating cow at farm level. It appears from this study that an overall prevalence of SCM was 51.56% in milking cows at Banaripara Upazilla, Barisal. Crossbred cows were significantly affected with SCM than local breed lactating cows. The farm type affect significantly (p<0.05) on the occurrence of this diseases. The prevalence of sub-clinical mastitis in cow was significantly (p<0.05) higher in 3rd (80%) parity compared to 1st (38.09%) and 2rd (45.83%) parity as well as non pregnant cows (55.55%) are more prone to infection than pregnant cow (46.43%). The farm floor condition and aged cows dont have any effect on SCM. Prevalence of sub-clinical mastitis was significantly (p<0.05) higher in high yielding (87.5%) cows than medium (70%) to low (33.33%) yielding cows. A well documented continued research and educational effort is required to increase producer awareness of cost due to mastitis to the dairy enterprise. From this study it was concluded that cow breed, farm type, parity of cows, physiological status of animal and milk yield per cow were found to be important risk factors associated with the occurrence of sub clinical mastitis in dairy cows. The occurrence of this disease remains a substantial problem for dairy producers.
PREVALENCE AND MOLECULAR DETECTION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS FROM DOGS AND CATS IN DHAKA CITY
Authors: Habibullah A. , Rahman A. M. M. T. , Haydar M. R. , Nazir K. H. M. N. H. , Rahman M. T.
Published: September 2017

Pet (dog and cat) animal numbers have substantially increased in modern society. There is concern over transmission of Staphylococcal infection including methicillin-resistant Staphylococcus aureus (MRSA) between animals and humans. The objective of the present study was to determine the prevalence of MRSA from apparently healthy and diseased dog and cat of different veterinary Hospital, clinics and pet animal market in Dhaka city. Samples collected for detection of MRSA were nasal swab, pus and wound swab. Among the 93 samples, 40.86% (n=38/93) were confirmed as positive for S. aureus and4.30% (n=4/93) as MRSA. The detection of MRSA was confirmed phenotypically and also by PCR targeting mec Agene specific for MRSA. All isolates isolated S. aureus were coagulase positive and hence pathogenic. Antibiogram study showed that all these isolates were sensitive to vancomycin and tetracycline. The overall prevalence of MRSA was higher in dog (4.91%) compared to cat (3.13%). The highest prevalence of MRSA (5.88%) was recorded in samples collected from Kataban Pet Animal Market, Dhaka. On sample basis MRSA was higher in nasal swab compared to pus and wound swab. On age basis, the prevalence of MRSA was higher in younger animal compared to older animal. The highest prevalence of S. aureus was found in diseased dog and highest prevalence of MRSA was found in diseased cat. None of the healthy cat was found positive for MRSA. Present study emphasizes that dogs and cats may act as a possible reservoirs for transmission of MRSA to human.
A Precise Positioning Method for a Puncture Robot Based on a PSO-Optimized BP Neural Network Algorithm
Authors: Jiang Guanwu , Luo Minzhou , Bai Keqiang , Chen Saixuan
Published: September 2017

The problem of inverse kinematics is fundamental in robot control. Many traditional inverse kinematics solutions, such as geometry, iteration, and algebraic methods, are inadequate in high-speed solutions and accurate positioning. In recent years, the problem of robot inverse kinematics based on neural networks has received extensive attention, but its precision control is convenient and needs to be improved. This paper studies a particle swarm optimization (PSO) back propagation (BP) neural network algorithm to solve the inverse kinematics problem of a UR3 robot based on six degrees of freedom, overcoming some disadvantages of BP neural networks. The BP neural network improves the convergence precision, convergence speed, and generalization ability. The results show that the position error is solved by the research method with respect to the UR3 robot inverse kinematics with the joint angle less than 0.1 degrees and the output end tool less than 0.1 mm, achieving the required positioning for medical puncture surgery, which demands precise positioning of the robot to less than 1 mm. Aiming at the precise application of the puncturing robot, the preliminary experiment has been conducted and the preliminary results have been obtained, which lays the foundation for the popularization of the robot in the medical field.
Crystals 2017 Best Paper Award
Authors:   Crystals Editorial Office
Published: September 2017

Crystals is instituting the Best Paper Award to recognize the outstanding papers published in the journal. We are pleased to announce the “Crystals Best Paper Award” for 2017. [...]
Exergy Analysis of a Pilot Parabolic Solar Dish-Stirling System
Authors: Gholamalizadeh Ehsan , Chung Jae
Published: September 2017

Energy and exergy analyses were carried out for a pilot parabolic solar dish-Stirling System. The system was set up at a site at Kerman City, located in a sunny desert area of Iran. Variations in energy and exergy efficiency were considered during the daytime hours of the average day of each month in a year. A maximum collector energy efficiency and total energy efficiency of 54% and 12.2%, respectively, were predicted in July, while during the period between November and February the efficiency values were extremely low. The maximum collector exergy efficiency was 41.5% in July, while the maximum total exergy efficiency reached 13.2%. The values of energy losses as a percentage of the total losses of the main parts of the system were also reported. Results showed that the major energy and exergy losses occurred in the receiver. The second biggest portion of energy losses occurred in the Stirling engine, while the portion of exergy loss in the concentrator was higher compared to the Stirling engine. Finally, the performance of the Kerman pilot was compared to that of the EuroDish project.
Forecasting of Chinese Primary Energy Consumption in 2021 with GRU Artificial Neural Network
Authors: Liu Bingchun , Fu Chuanchuan , Bielefield Arlene , Liu Yan
Published: September 2017

The forecasting of energy consumption in China is a key requirement for achieving national energy security and energy planning. In this study, multi-variable linear regression (MLR) and support vector regression (SVR) were utilized with a gated recurrent unit (GRU) artificial neural network of Chinese energy to establish a forecasting model. The derived model was validated through four economic variables; the gross domestic product (GDP), population, imports, and exports. The performance of various forecasting models was assessed via MAPE and RMSE, and three scenarios were configured based on different sources of variable data. In predicting Chinese energy consumption from 2015 to 2021, results from the established GRU model of the highest predictive accuracy showed that Chinese energy consumption would be likely to fluctuate from 2954.04 Mtoe to 5618.67 Mtoe in 2021.
How Wood Fuels’ Quality Relates to the Standards: A Class-Modelling Approach
Authors: Zanetti Michela , Costa Corrado , Greco Rosa , Grigolato Stefano , Ottaviani Aalmo Giovanna , Cavalli Raffaele
Published: September 2017

The quality requirements of wood biofuels are regulated by a series of harmonized international standards. These standards define the technical parameter limits that influence the quality of solid biomass as a fuel. In 2014 the European reference standard for solid biofuel was replaced by the International ISO standard. In the case of wood chips, the main difference between the European and International standards is the definition of particle size distribution classes. In this context, this study analyses the quality of wood chips and its variation over the years according to the “former” (EN 14691-4) and “in force” (ISO 17225-4) standards. A Soft Independent Modelling of Class Analogy (SIMCA) model was built to predict the best quality of wood chips and to clarify the relationship between quality and standard parameters, time and changes in the standard regulations. The results show that, compared to the EN standards, classification with the ISO standards increases the samples belonging to the best quality classes and decreases the not classified samples. Furthermore, all the SIMCA models have a high sensitivity (>90%), reflect the differences introduced to the quality standards and are therefore suitable for monitoring the quality of wood chips and their changes.
Analysis of Porous Structure Parameters of Biomass Chars Versus Bituminous Coal and Lignite Carbonized at High Pressure and Temperature—A Chemometric Study
Authors: Smoliński Adam , Howaniec Natalia
Published: September 2017

The characteristics of the porous structure of carbonized materials affect their physical properties, such as density or strength, their sorption capacity, and their reactivity in thermochemical processing, determining both their applicability as fuels or sorbents and their efficiency in various processes. The porous structure of chars is shaped by the combined effects of physical and chemical properties of a carbonaceous material and the operating parameters applied in the carbonization process. In the study presented, the experimental dataset covering parameters of various fuels, ranging from biomass through lignite to bituminous coal, and chars produced at 1273 K and under the pressure of 1, 2, 3, and 4 MPa was analyzed with the application of the advanced method of data exploration. The principal component analysis showed that the sample of the highest coal rank was characterized by lower values of parameters reflecting the development of the porous structure of chars. A negative correlation was also observed between the carbon content in a fuel and the evolution of the porous structure of chars at high pressure. The highest total pore volume of chars produced under 1 and 3 MPa and the highest micropore surface area under 3 MPa were reported for a carbonized fuel sample of the highest moisture content.
Magnet-Sleeve-Sealed Mini Trochoidal-Gear Pump Prototype with Polymer Composite Gear
Authors: Gamez-Montero Pedro , Antoniak Piotr , Castilla Robert , Freire Javier , Krawczyk Justyna , Stryczek Jaroslaw , Codina Esteve
Published: September 2017

The trochoidal-gear technology has been growing in groundbreaking fields. Forthcoming applications are demanding to this technology a step forward in the conceiving stage of positive displacement machines. The compendium of the qualities and the inherent characteristics of trochoidal-gear technology, especially towards the gerotor pump, together with scale/size factor and magnetic-driven transmission has led to the idea of a magnet-sleeve-sealed variable flow mini trochoidal-gear pump. From its original concept, to the last phase of the design development, the proof of concept, this new product will intend to overcome problems such as noise, vibration, maintenance, materials, and dimensions. The paper aims to show the technological path followed from the concept, design, and model, to the manufacture of the first prototype, where the theoretical and numerical approaches are not always directly reflected in the prototype performance results. Early in the design process, from a standard-commercial sintered metal mini trochoidal-gear unit, fundamental characteristics and dimensional limitations have been evaluated becoming the strategic parameters that led to its configuration. The main technical challenge to confront is being sealed with non-exterior driveshaft, ensuring that the whole interior is filled and wetted with working fluid and helping the hydrodynamic film formation, the pumping effect, and the heat dissipation. Subsequently, the mini pump architecture, embodiment, methodology, materials, and manufacture are presented. The trend of applications of polymer composite materials and their benefits wanted to be examined with this new mini pump prototype, and a pure polyoxymethylene mini trochoidal-gear set has been designed and manufactured. Finally, both the sintered and the polymer trochoidal-gear units have been experimentally tested in an in-house full-instrumented mini test bench. Although the main goal of the presented work is the development of a new mini trochoidal-gear pump prototype rather than a numerical study, the results have been compared with numerical simulation. Subsequently, the prototype of the mini trochoidal-gear pump is a feasible proof of concept supported by functional indexes and the experimental results.
Development of Genome-Wide SSR Markers from Angelica gigas Nakai Using Next Generation Sequencing
Authors: Gil Jinsu , Um Yurry , Kim Serim , Kim Ok , Koo Sung , Reddy Chinreddy , Kim Seong-Cheol , Hong Chang , Park Sin-Gi , Kim Ho , Lee Dong , Jeong Byung-Hoon , Chung Jong-Wook , Lee Yi
Published: September 2017

Angelica gigas Nakai is an important medicinal herb, widely utilized in Asian countries especially in Korea, Japan, and China. Although it is a vital medicinal herb, the lack of sequencing data and efficient molecular markers has limited the application of a genetic approach for horticultural improvements. Simple sequence repeats (SSRs) are universally accepted molecular markers for population structure study. In this study, we found over 130,000 SSRs, ranging from di- to deca-nucleotide motifs, using the genome sequence of Manchu variety (MV) of A. gigas, derived from next generation sequencing (NGS). From the putative SSR regions identified, a total of 16,496 primer sets were successfully designed. Among them, we selected 848 SSR markers that showed polymorphism from in silico analysis and contained tri- to hexa-nucleotide motifs. We tested 36 SSR primer sets for polymorphism in 16 A. gigas accessions. The average polymorphism information content (PIC) was 0.69; the average observed heterozygosity (HO) values, and the expected heterozygosity (HE) values were 0.53 and 0.73, respectively. These newly developed SSR markers would be useful tools for molecular genetics, genotype identification, genetic mapping, molecular breeding, and studying species relationships of the Angelica genus.
Role of the Genes of Type VI Secretion System in Virulence of Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae Strain RS-2
Authors: Masum Md. , Yang Yingzi , Li Bin , Olaitan Ogunyemi , Chen Jie , Zhang Yang , Fang Yushi , Qiu Wen , Wang Yanli , Sun Guochang
Published: September 2017

The Type VI secretion system (T6SS) is a class of macromolecular machine that is required for the virulence of gram-negative bacteria. However, it is still not clear what the role of T6SS in the virulence of rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae (Aaa) is. The aim of the current study was to investigate the contribution of T6SS in Aaa strain RS2 virulence using insertional deletion mutation and complementation approaches. This strain produced weak virulence but contains a complete T6SS gene cluster based on a genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type (RS-2) and 25 T6SS mutants, which were constructed using homologous recombination methods. The mutation of 15 T6SS genes significantly reduced bacterial virulence and the secretion of Hcp protein. Additionally, the complemented 7 mutations ΔpppA, ΔclpB, Δhcp, ΔdotU, ΔicmF, ΔimpJ, and ΔimpM caused similar virulence characteristics as RS-2. Moreover, the mutant ΔpppA, ΔclpB, ΔicmF, ΔimpJ and ΔimpM genes caused by a 38.3~56.4% reduction in biofilm formation while the mutants ΔpppA, ΔclpB, ΔicmF and Δhcp resulted in a 37.5~44.6% reduction in motility. All together, these results demonstrate that T6SS play vital roles in the virulence of strain RS-2, which may be partially attributed to the reductions in Hcp secretion, biofilm formation and motility. However, differences in virulence between strain RS-1 and RS-2 suggest that other factors may also be involved in the virulence of Aaa.