bluuebunny/crossref_metadata_2025 huggingface dataset:
The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem
Authors: Nielsen U. N. , Wall D. H. , Adams B. J. , Virginia R. A. , Ball B. A. , Gooseff M. N. , McKnight D. M.
Published: February 2012

Climate change is occurring globally, with wide ranging impacts on organisms and ecosystems alike. While most studies focus on increases in mean temperatures and changes in precipitation, there is growing evidence that an increase in extreme events may be particularly important to altering ecosystem structure and function. During extreme events organisms encounter environmental conditions well beyond the range normally experienced. Such conditions may cause rapid changes in community composition and ecosystem states. We present the impact of an extreme pulse event (a flood) on soil communities in an Antarctic polar desert. Taylor Valley, McMurdo Dry Valleys, is dominated by large expanses of dry, saline soils. During the austral summer, melting of glaciers, snow patches and subsurface ice supplies water to ephemeral streams and wetlands. We show how the activation of a non‐annual ephemeral stream, Wormherder Creek, and the associated wetland during an exceptional high‐flow event alters soil properties and communities. The flow of water increased soil water availability and decreased salinity within the wetted zone compared with the surrounding dry soils. We propose that periodic leaching of salts from flooding reduces soil osmotic stress to levels that are more favorable for soil organisms, improving the habitat suitability, which has a strong positive effect on soil animal abundance and diversity. Moreover, we found that communities differentiated along a soil moisture gradient and that overland water flow created greater connectivity within the landscape, and is expected to promote soil faunal dispersal. Thus, floods can ‘precondition' soils to support belowground communities by creating conditions below or above key environmental thresholds. We conclude that pulse events can have significant long‐term impacts on soil habitat suitability, and knowledge of pulse events is essential for understanding the present distribution and functioning of communities in soil ecosystems.
Teaching with Transmedia
Authors: Pence Harry E.
Published: February 2012

The media environment is currently being dramatically changed by social networking, mobile computing, augmented reality, and transmedia. Of these four, transmedia is probably the least familiar to most educators. Transmedia enhances a central story idea with a variety of media components that provide additional information, give increased importance to minor characters in the main narrative, or even add new characters that were not in the original story. These techniques are already being widely used for movies, television, and advertising. They also offer significant advantages for education, although it will require some major adjustments in order for them to become accepted in higher education.
Kassia’s hymnography in the light of patristic sources and earlier hymnographical works
Authors: Simic Kosta
Published: February 2012

This paper examines Kassia?s use of patristic sources and earlier hymnography
in some of her authentic poetic works. Her use of the sources is scrutinized
in relation to three main themes developed in her poetry: a) the imperial
theme, b) the anti-iconoclastic polemic, and c) the ascetic ideal of life
according to nature.
The byzantine title of Constantine Bodin
Authors: Komatina Predrag
Published: February 2012

The paper considers the use of the title exousiastes on the newly discovered
seal of Constantine Bodin. It analyses the meaning and use of this title in
the sources of a diplomatic character of the 10th century, as well as its
use in the 11th century sources. The question is posed why this title was
used on Bodin?s seal instead of the title archon, which had been used for
former Serbian rulers, as well as whether this phenomenon had any connection
to the fact that Serbian rulers, beginning at the end of the rule of Bodin?s
father Michael, used the title of king.
Die macht des historiographen - Andronikos (I.) Komnenos und sein bild
Authors: Grunbart Michael
Published: February 2012

In the church of the Forty Martyrs at Constantinople Andronikos Komnenos
(emperor 1183-1185) was depicted. The image led to various interpretations,
but the historical sequence (based on Nicetas Choniates) and a passage
written by Nicolas Mesarites offer another solution: Alexios II. was crowned
by Andronikos, who performed as protector of the young emperor.
Serbian pronoia and pronoia in Serbia: The diffusion of an institution
Authors: Bartusis Mark
Published: February 2012

Of all of Byzantium?s neighbors who appropriated the fiscal and agrarian
institution of pronoia, it was the Serbs whose adaptation of the institution
most closely resembled the Byzantine model. The article re-examines the
institution of pronoia in Serbia from its earliest manifestation during the
reign of Stefan Uros II Milutin through the time of the Brankovici in the
mid-fifteenth century. In the course of analyzing the character of Serbian
pronoia, particularly during the reign of Stefan Dusan, the administration of
conquered Byzantine pronoiai is distinguished from the creation of pronoiai
in native Serbian territory.
Skazanie o pismeneh by Constantine the philosopher Kostenecki as a source of folk culture in the middle ages
Authors: Bojanin Stanoje
Published: February 2012

The research of folk culture in the Middle Ages requires a special
methodological approach which includes both defining the notion of ?folk
culture? and the question of the existing sources and their use. This study
demonstrates the importance for the Skazanie o pismeneh by Constantine the
Philosopher Kostenecki, as a source for the folk culture of medieval Serbia
and Southeastern Europe at the end of the 14th and the beginning of the 15th
century. Although this work is well-known in scholarly circles, so far it
has not been considered in the context of the said domain of research. In
order to correctly understand the data contained in the Skazanie, it was
examined not only in relation to similar data but also in very close
connection with the motives for the creation of the work and the cultural
concepts advocated by its author, which had little affinity for folk
culture.
Associations between cerebrospinal fluid biomarkers and long-term neurologic outcome in dogs with acute intervertebral disk herniation
Authors: Witsberger Tige H. , Levine Jonathan M. , Fosgate Geoffrey T. , Slater Margaret R. , Kerwin Sharon C. , Russell Karen E. , Levine Gwendolyn J.
Published: February 2012

Objective—To examine associations between CSF biomarkers, initial neurologic dysfunction, and long-term ambulatory outcome in dogs with acute intervertebral disk herniation (IVDH).

Design—Prospective clinical study.

Animals—54 dogs with acute thoracolumbar IVDH and 16 clinically normal dogs.

Procedures—For each dog, variables, including CSF myelin basic protein (MBP), lactate, calcium, glucose, and total protein concentrations; nucleated cell count; and creatine kinase (CK) and aspartate aminotransferase activities, were measured. For dogs with thoracolumbar IVDH, initial neurologic function was characterized by use of a modified Frankel score (MFS; determined on a scale of 0 to 5, where 0 represented paraplegia with no deep nociception and 5 represented paraspinal hyperesthesia only). Long-term follow-up was assessed.

Results—Among dogs with thoracolumbar IVDH, those with CSF CK activity ≤ 38 U/L had a 35-fold increase in the odds of long-term ambulation, compared with the odds in dogs with CSF CK activity > 38 U/L, adjusting for neurologic functioning at the evaluation. The CSF lactate, calcium, and glucose concentrations and aspartate aminotransferase activity were not predictive of long-term ambulatory outcome. Data analysis revealed that long-term functional recovery was > 98% for affected dogs, regardless of their initial MFS, when CSF CK activity was ≤ 38 U/L and MBP concentration was ≤ 3 ng/mL.

Conclusions and Clinical Relevance—In dogs with acute thoracolumbar IVDH, CSF CK activity and MBP concentration appeared to be prognostic indicators and, along with initial MFS, can be used to predict long-term ambulatory outcome.
Associations among weight loss, stress, and upper respiratory tract infection in shelter cats
Authors: Tanaka Aki , Wagner Denae C. , Kass Philip H. , Hurley Kate F.
Published: February 2012

Objective—To identify associations among change in body weight, behavioral stress score, food intake score, and development of upper respiratory tract infection (URI) among cats admitted to an animal shelter.

Design—Prospective cohort study.

Animals—60 adult cats admitted to an animal shelter.

Procedures—Body weight was measured on days 0 (intake), 7, 14, and 21. Behavioral stress and food intake were scored daily for the first 7 days; cats were monitored daily for URI.

Results—49 of the 60 (82%) cats lost weight during at least 1 week while in the shelter. Fifteen (25%) cats lost ≥ 10% of their body weight while in the shelter. Thirty-five of the 60 (58%) cats developed URI prior to exiting the shelter, and only 4 cats remained at least 21 days without developing URI. Cats with high stress scores during the first week were 5.6 times as likely to develop URI as were cats with low stress scores. Food intake and stress scores were negatively correlated (r = −0.98).

Conclusions and Clinical Relevance—Results indicated that cats admitted to an animal shelter were likely to lose weight while in the shelter and likely to develop URI, and that cats that had high stress scores were more likely to develop URI.
Functionality of implanted microchips following magnetic resonance imaging
Authors: Haifley Katherine A. , Hecht Silke
Published: February 2012

Objective—To determine the functionality of implanted microchips following magnetic resonance imaging (MRI).

Design—Prospective clinical trial.

Animals—53 client-owned patients implanted with a microchip undergoing MRI of various areas of the body for a variety of medical conditions.

Procedures—General anesthesia was induced, and each patient's microchip was scanned with a universal microchip scanner; the chip number was recorded. Patients were transported to the MRI suite, and MRI was completed. Patients were moved out of the magnetic environment, and microchips were scanned again. Patient information and chip number were recorded. Chip numbers before and after MRI were compared.

Results—For all 53 microchips scanned from 53 patients, the same number was read accurately following MRI of a variety of sites.

Conclusions and Clinical Relevance—These data indicated that MRI did not interfere with the functionality of these microchips. This information is valuable for practitioners recommending MRI for their patients and for clients who have invested in implanting a microchip in their pets.
Meningitis and meningoencephalomyelitis in horses: 28 cases (1985–2010)
Authors: Toth Balazs , Aleman Monica , Nogradi Nora , Madigan John E.
Published: February 2012

Objective—To describe clinical and clinicopathologic findings and outcome of horses with meningitis and meningoencephalomyelitis.

Design—Retrospective case series.

Animals—28 horses.

Procedures—Medical records of horses admitted to the hospital during a 25-year period were reviewed. Horses with a definitive diagnosis of meningitis or meningoencephalomyelitis were included in this study. Information extracted from the medical records included signalment, history, reason for admission, clinical signs, results of clinicopathologic testing and diagnostic procedures, treatment, outcome, and necropsy findings.

Results—22 horses had confirmed infectious disease (19 bacterial, 2 parasitic, and 1 fungal), 4 had suspected infectious disease on the basis of CSF cytologic examination findings, and 2 had noninfectious meningitis or meningoencephalomyelitis. Trauma of the head and vertebral column with disruption of the blood-brain barrier and local ascending or hematogenous spread were the most common routes of infection. Common neurologic signs included abnormal mental status, cranial nerve deficits, vestibular dysfunction, ataxia, tetraparesis, and apparent neck pain. Common hematologic abnormalities included leukocytosis, neutrophilia, lymphopenia, and hyperfibrinogenemia. Cytologic examination of CSF samples revealed moderate to marked suppurative inflammation. Mortality rate was 96.4%. Microbial culture of CSF yielded bacterial growth in 15 of 23 horses (before death [2 horses], after death [11], and both [2]).

Conclusions and Clinical Relevance—Results suggested that meningitis and meningoencephalomyelitis are uncommon disorders in horses. Infectious disease was more common than noninfectious disease. Local trauma, ascending infection, or hematogenous spread of infection were the most common causes of meningitis or meningoencephalomyelitis. Neurologic deficits, neutrophilia, lymphopenia, hyperfibrinogenemia, and CSF with neutrophilic pleocytosis were common findings in affected horses.
Evaluation of two point-of-care meters and a portable chemistry analyzer for measurement of blood glucose concentrations in juvenile white-tailed deer (Odocoileus virginianus)
Authors: Burdick Stacy , Mitchell Mark A. , Neil Johanna , Heggem Brittany , Whittington Julia , Acierno Mark J.
Published: February 2012

Objective—To evaluate agreement of blood glucose concentrations measured in juvenile white-tailed deer (Odocoileus virginianus) by use of 2 point-of-care (POC) blood glucose meters and 1 portable chemistry analyzer with values obtained in serum by use of a standard laboratory chemistry analyzer, and to evaluate agreement between results obtained with the 2 POC meters.

Design—Prospective evaluation study.

Sample—14 venous blood samples from 14 healthy white-tailed deer fawns.

Procedures—Blood glucose concentration was measured with each of 2 POC meters. The remainder of the sample was divided into 2 tubes (1 that contained lithium heparin and 1 with no anticoagulant). Glucose concentration in anticoagulated whole blood was measured with the portable analyzer. Serum was collected from the remaining sample for measurement of glucose concentrations with the laboratory analyzer. Bland-Altman plots were used to assess agreement.

Results—Agreement between POC blood glucose meters and the laboratory analyzer was poor; mean values for bias were 2.9 mg/dL (95% limits of agreement [LOA], −70.2 to 76.0 mg/dL) and −30.8 mg/dL (95% LOA, −111.6 to 49.9 mg/dL), respectively. Agreement between the 2 POC meters was also poor (bias, 31.0 mg/dL; 95% LOA, −47.2 to 109.2 mg/dL). Agreement between the portable analyzer and the laboratory analyzer was good (bias, −1.6 mg/dL; 95% LOA, −15.3 to 12.1 mg/dL).

Conclusions and Clinical Relevance—Results suggested that the POC blood glucose meters used in this study are not appropriate for measurement of blood glucose concentrations in juvenile white-tailed deer.
A model to calculate the viscosity of silicate melts
Authors: Brosh Eli , Pelton Arthur D. , Decterov Sergei A.
Published: February 2012

Our recently developed model for the viscosity of silicate melts is extended to describe and predict the viscosities of oxide melts containing boron. The model requires three adjustable parameters to reproduce the viscosity of B2O3–SiO2 melts and two parameters for each B2O3–MO
x
melt, where MO
x
is a basic oxide other than an alkali oxide. All available experimental data have been collected for binary melts formed by B2O3 with SiO2, Al2O3, CaO, MgO, ZnO, PbO to calibrate the model. The viscosities of the B2O3-containing ternary and higher-order subsystems of the B2O3–CaO–MgO–PbO–ZnO–SiO2 system and of the B2O3–CaO–MgO–PbO–ZnO–Al2O3 system are then predicted by the model without any additional adjustable parameters. Experimental data were found for only five such subsystems: B2O3–PbO–SiO2, B2O3–CaO–SiO2, B2O3–PbO–ZnO, B2O3–PbO–Al2O3 and B2O3–CaO–Al2O3. Predictions of the model are compared to these experimental data.
A model to calculate the viscosity of silicate melts
Authors: Brosh Eli , Pelton Arthur D. , Decterov Sergei A.
Published: February 2012

Our recently developed model for the viscosity of borosilicate melts is extended to describe and predict the viscosities of melts containing alkali oxides. In addition to the two model parameters that are required for each B2O3–MO
x
melt, where MO
x
is a basic oxide, three more parameters are needed when MO
x
is an alkali oxide to account for the formation of clusters near the tetraborate composition. The additional parameters represent the size and Gibbs energy of formation of these clusters and their contribution to the activation energy of the viscous flow. A general algorithm for the calculation of the viscosity is presented which summarizes the application of the viscosity model to melts that can contain two network formers, SiO2 and B2O3, any basic oxide and amphoteric oxides exhibiting the Charge Compensation Effect such as Al2O3. The predictive ability of the model is tested on all ternary subsystems of the B2O3–Na2O–K2O–CaO–MgO–PbO–ZnO–Al2O3–SiO2 system containing both an alkali oxide and B2O3 for which experimental data are available and on several multicomponent glass-forming melts around commercial glass compositions.
Preparation and characterization of low temperature sintering nanocrystalline TiO2prepared via the sol-gel method using titanium(IV) butoxide applicable to flexible dye sensitized solar cells
Authors: Bazargan M. Hossein , Byranvand M. Malekshahi , Kharat A. Nemati
Published: February 2012

Low temperature nanocrystalline titanium dioxide particles were prepared via the sol-gel method using titanium(IV) butoxide for fabrication of flexible dye sensitized solar cells. The prepared sample was characterized using X-ray powder diffraction, specific surface area, transmission electron microscopy, scanning electron microscopy and atomic force microscopy. Results confirm that the synthesized sample was highly crystalline anatase TiO2with an average particle size of 35 nm. The measured specific surface area for TiO2powder and average surface roughness for TiO2film were 61.11 m2g−1and 17.25 nm respectively. The prepared nano-scale TiO2was then employed to fabricate flexible dye sensitized solar cell via the low temperature sintering and operated with a platinum counter electrode. The solar energy conversion efficiency for the cell fabricated with TiO2nanoparticles was about 0.85%.
Growth of rare-earth zirconates-based pyrochlore buffer layers on YSZ for YBCO-coated conductors via chemical solution deposition
Authors: Shen Ya , Zhang Guofang , Li Chengshan , Yu Zeming , Jin Lihua , Wang Yao , Lu Yafeng
Published: February 2012

Epitaxial films of rare-earth zirconates, RE2Zr2O7 (RE = La, Nd, Sm and Gd) were grown on yttrium stabilized zirconia (100) single crystal substrates using metal-organic deposition. A precursor solution of 0.25 '0.40 M concentration of total cations was spin-coated on yttrium stabilized zirconia substrates and crystallized at 1 000 8C for 3 h in Ar-4%H2 after calcination at 500 8C for 1 h. X-ray diffraction studies showed that the resulting pyrochlore RE2Zr2O7 films were highly textured with cube-on-cube epitaxy. Atomic force microscopy investigations revealed that the surfaces of La2Zr2O7, Nd2Zr2O7 and Sm2Zr2O7 films had a fairly dense and smooth microstructure without cracks and porosity, but that voids could be seen on the surface of the Gd2Zr2O7 film. Optical microscopy measurements confirmed that the Gd2Zr2O7 precursor solution showed poor wetting behavior on the substrate. It was concluded that the Nd2Zr2O7 and Sm2Zr2O7 films could be potentially used as buffer layers for YBa2Cu3O7-d coated conductors.
Li–Cr substituted nickel–zinc–copper ferrite powders: structural and magnetic properties
Authors: Xia Ailin , Liu Shunkai , Jin Chuangui , Du Dexin , Hu Jinlian
Published: February 2012

Li–Cr substituted NiZnCu ferrite powder specimens with the nominal composition Ni0.
25
–2

x
Li
x
Cr
x
Cu0.15Zn0.6Fe2O4 (x=0.00, 0.01, 0.02, 0.03, 0.04) were prepared primarily via chemical coprecipitation. X-ray diffractometry, scanning electron microscopy and vibrating sample magnetometry were used to study their structural or magnetic properties. It is found that all the specimens exhibit a single phase after annealing. The variation tendency of saturation magnetization with x exhibts a strange variation tendency and can be attributed to the different site occupation of Li+ions. It is also found that suitable Li–Cr substitutions help decrease the annealing temperature.
Flow dynamics of an accumulation basin: a case study of upper Kahiltna Glacier, Mount McKinley, Alaska
Authors: Campbell Seth , Kreutz Karl , Osterberg Erich , Arcone Steven , Wake Cameron , Volkening Kevin , Winski Dominic
Published: February 2012

We interpreted flow dynamics of the Kahiltna Pass Basin accumulation zone on Mount McKinley, Alaska, USA, using 40,100 and 900 MHz ground-penetrating radar profiles and GPS surface velocity measurements. We found dipping, englacial surface-conformable strata that experienced vertical thickening as the glacier flowed westward from a steep, higher-velocity (60 m a-1) region into flat terrain associated with a 90° bend in the glacier and lower velocities (15 m a-1) to the south. Stratigraphy near the western side of the basin was surface-conformable to ˜170m depth and thinned as flow diverged southward, down-glacier. We found complex strata beneath the conformable stratigraphy and interpret these features as buried crevasses, avalanche debris and deformed ice caused by up-glacier events. We also suggest that basin dimensions, bed topography and the sharp bend each cause flow extension and compression, significantly contributing to conformable and complex strata thickness variations. Our findings show that surface-conformable stratigraphy continuous with depth and consistent strata thicknesses cannot be assumed in accumulation basins, because local and up- glacier terrain and flow dynamics can cause structural complexities to occur under and within surface- conformable layers.
Subglacial clast/bed contact forces
Authors: Byers John , Cohen Denis , Iverson Neal R
Published: February 2012

A laboratory device was built to measure the forces that ice exerts on a 0.05 m diameter rigid plastic sphere in two different configurations: in contact with a flat bed or isolated from the bed. Measurements indicated that bed-normal contact forces were 1.8 times larger than drag forces due to creeping flow past a slippery sphere isolated from the bed. Measurements of forces as a function of the bed-normal ice velocity, estimations of the ice viscosity parameter and observations of markers in the ice indicate ice is Newtonian with a viscosity of ~1.3x 1011 Pas. Newtonian behavior is expected due to small and transient stresses. A model of regelation indicates that it had a negligible (<5%) influence on forces. Water pressure in the cavity beneath the sphere in contact with the bed had a likewise negligible influence on contact forces. When no cavity is present, drag forces can be correctly estimated using Stokes’s law (Newtonian viscosity) for a slippery sphere. The same law with a bed-enhancement factor of 1.8 is appropriate for estimating bed-normal contact forces. These results reinforce previous laboratory measurements and theories but provide no support for explanations of high debris/bed friction or rates of abrasion that depend on high contact forces.
Variational assimilation of albedo in a snowpack model and reconstruction of the spatial mass-balance distribution of an alpine glacier
Authors: Dumont Marie , Durand Yves , Arnaud Yves , Six Delphine
Published: February 2012

Accurate knowledge of the spatial distribution of the mass balance of temperate glaciers is essential for a better understanding of the physical processes controlling the mass balance and for the monitoring of water resources. In relation to albedo variations, the shortwave radiation budget is a controlling variable of the surface energy balance of glaciers. Remotely sensed albedo observations are here assimilated in a snowpack model to improve the modeling of the spatial distribution of the glacier mass balance. The albedo observations are integrated in the snowpack simulation using a variational data assimilation scheme that modifies the surface grain conditions. The study shows that mesoscale meteorological variables and MODIS-derived albedo maps can be used to obtain a good reconstruction of the annual mass balance on Glacier de Saint-Sorlin, French Alps, on a 100 m × 100m grid. Five hydrological years within the 2000-10 decade are tested. The accuracy of the method is estimated from comparison with field measurements. Sensitivity to roughness lengths and winter precipitation fields is investigated. Results demonstrate the potential contribution of remote-sensing data and variational data assimilation to further improve the understanding and monitoring of the mass balance of snowpacks and temperate glaciers.
Glacier recession and water resources in Peru’s Cordillera Blanca
Authors: Baraer Michel , Mark Bryan G. , McKenzie Jeffrey M. , Condom Thomas , Bury Jeffrey , Huh Kyung-In , Portocarrero Cesar , Gómez Jesús , Rathay Sarah
Published: February 2012

The tropical glaciers of the Cordillera Blanca, Peru, are rapidly retreating, resulting in complex impacts on the hydrology of the upper Río Santa watershed. The effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points. Using the Mann-Kendall nonparametric statistical test, the significance of trends in three hydrograph parameters was studied. Results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences. The results suggest that seven of the nine study watersheds have probably crossed a critical transition point, and now exhibit decreasing dry-season discharge. Our results suggest also that once the glaciers completely melt, annual discharge will be lower than present by 2-30% depending on the watershed. The retreat influence on discharge will be more pronounced during the dry season than at other periods of the year. At La Balsa, which measures discharge from the upper Río Santa, the glacier retreat could lead to a decrease in dry-season average discharge of 30%.
Fracture field for large-scale ice dynamics
Authors: Albrecht Torsten , Levermann Anders
Published: February 2012

Recent observations and modeling studies emphasize the crucial role of fracture mechanics for the stability of ice shelves and thereby the evolution of ice sheets. Here we introduce a macroscopic fracture-density field into a prognostic continuum ice-flow model and compute its evolution incorporating the initiation and growth of fractures as well as their advection with two dimensional ice flow. To a first approximation, fracture growth is assumed to depend on the spreading rate only, while fracture initiation is defined in terms of principal stresses. The inferred fracture-density fields compare well with observed elongate surface structures. Since crevasses and other deep-reaching fracture structures have been shown to influence the overall ice-shelf dynamics, we propose the fracture- density field introduced here be used as a measure for ice softening and decoupling of the ice flow in fracture-weakened zones. This may yield more accurate and realistic velocity patterns in prognostic simulations. Additionally, the memory of past fracture events links the calving front to the upstream dynamics. Thus the fracture-density field proposed here may be employed in fracture-based calving parameterizations. The aim of this study is to introduce the field and investigate which of the observed surface structures can be reproduced by the simplest physically motivated fracture source terms.
Evolving Antibiotic Resistance: A Great Threat to Medical Practice
Authors: Chowdhury MAK Azad
Published: February 2012

DOI: http://dx.doi.org/10.3329/bjms.v11i1.9814 BJMS 2012; 11(1): 1-3
Interactions of Guanine with Cr(VI), Ag(I), Cd(II) and Hg(II) in Acidic Aqueous Medium
Authors: Shaikh AA , Paul Dilip K , Rahman MS , Bakshi Pradip K
Published: February 2012

Guanine forms compounds with Cr(VI), Ag(I), Cd(II) and Hg(II) in acidic aqueous media. The compounds are formulated as (C5H6N5O)2(Cr2O7).H2O, [Ag{(C5H6N5O)(NO3)}2](C5H6N5O)(NO3)2, [(C5H4N5O)2Cd](C5H6N5O)Cl and [(C5H4N5O)2Hg](C5H6N5O)Cl on the basis of their metal and chloride contents.  Physico-chemical properties such as solubility, melting point, IR and UV-visible spectra, magnetic susceptibility, and thermal behavior of the compounds were studied. The composition of (C5H6N5O)2(Cr2O7).H2O was also investigated by continuous variation method. Keywords: Nucleic acids; Guaninium ions; Pyrimidine ring; Magnetic susceptibilities. DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9699 Journal of Bangladesh Chemical Society, Vol. 24(2), 106-114, 2011
A cyclic voltammetric study of the influence of supporting electrolytes on the redox behaviour of Cu(II) in aqueous medium
Authors: Shaikh Aftab Ali , Badrunnessa M , Firdaws Jannatul , Rahman Md Shahidur , Pasha Nishat Ahmed , Bakshi Pradip Kumar
Published: February 2012

The electrochemical redox behavior of Cu(II) has been investigated at glassy carbon electrode (GCE) in Britton-Robinson (BR) buffer as well as in a mixture of BR buffer and potassium chloride media. It is apparent that BR buffer can act as a supporting electrolyte and modify the electrochemical behavior of Cu(II) ion in aqueous medium. In BR buffer medium, Cu(II) undergoes one two-electrons redox process, while in a mixture of BR buffer and KCl media it follows two one-electron electrochemical reaction routes. Because of the formation of hydrogen bridge bond between the supporting electrolyte and GCE surface, the Cu(II) ion follows Cu(II)/Cu(0) electrochemical reaction path, while in presence of KCl such a hydrogen bridge bond is not formed and it undergoes successive Cu(II)/Cu(I) and Cu(I)/Cu(0) electrode reaction processes. Moreover, the linear variation of peak current with the square root of scan rate indicates that the electrochemical redox processes are diffusion controlled. Keywords: Supporting electrolytes; Britton-Robinson buffer; Cu-reduction; Peak current DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9704 Journal of Bangladesh Chemical Society, Vol. 24(2), 158-164, 2011
Comparative study of Bangladesh Barapukuria coal with those of various other countries
Authors: Safiullah S , Khan MRR , Sabur MA
Published: February 2012

Comparative study of the qualities of the Bangladeshi, Indian, Australian and Indonesian coals was made in terms of coking properties, calorific value, sulfur content, moisture, ash, volatile matters and carbon content. Bangladesh Barapukuria coal was found to be the best of all the coal samples with a carbon content of 56.47% and other qualities Bangladeshi coal clearly indicate that it is also suitable for value added utilization.   DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9712 Journal of Bangladesh Chemical Society, Vol. 24(2), 221-225, 2011
Web Service Assurance: The Notion and the Issues
Authors: Anisetti Marco , Ardagna Claudio A. , Damiani Ernesto , Frati Fulvio , Müller Hausi A. , Pahlevan Atousa
Published: February 2012

Web service technology provides basic infrastructure for deploying collaborative business processes. Web Service security standards and protocols aim to provide secure communication and conversation between service providers and consumers. Still, for a client calling a Web service it is difficult to ascertain that a particular service instance satisfies—at execution time—specific non-functional properties. In this paper we introduce the notion of certified Web service assurance, characterizing how service consumers can specify the set of security properties that a service should satisfy. Also, we illustrate a mechanism to re-check non-functional properties when the execution context changes. To this end, we introduce the concept of context-aware certificate, and describe a dynamic, context-aware service discovery environment.
Low Operational Stability of Enzymes in Dry Organic Solvents: Changes in the Active Site Might Affect Catalysis
Authors: Bansal Vibha , Delgado Yamixa , Legault Marc D. , Barletta Gabriel
Published: February 2012

The potential of enzyme catalysis in organic solvents for synthetic applications has been overshadowed by the fact that their catalytic properties are affected by organic solvents. In addition, it has recently been shown that an enzyme’s initial activity diminishes considerably after prolonged exposure to organic media. Studies geared towards understanding this last drawback have yielded unclear results. In the present work we decided to use electron paramagnetic resonance spectroscopy (EPR) to study the motion of an active site spin label (a nitroxide free radical) during 96 h of exposure of the serine protease subtilisin Carlsberg to four different organic solvents. Our EPR data shows a typical two component spectra that was quantified by the ratio of the anisotropic and isotropic signals. The isotropic component, associated with a mobile nitroxide free radical, increases during prolonged exposure to all solvents used in the study. The maximum increase (of 43%) was observed in 1,4-dioxane. Based on these and previous studies we suggest that prolonged exposure of the enzyme to these solvents provokes a cascade of events that could induce substrates to adopt different binding conformations. This is the first EPR study of the motion of an active-site spin label during prolonged exposure of an enzyme to organic solvents ever reported.
A New Triterpene From Uncaria macrophylla and Its Antitumor Activity
Authors: Sun Guangli , Zhang Xiaopo , Xu Xudong , Yang Junshan , Zhong Mingliang , Yuan Jingquan
Published: February 2012

On our ongoing investigation, a new oleanolic triterpene, 3β,6β,19α-trihydroxy-12-oleanen-28-oic acid (1) was obtained from the chloroform-soluble portion of the 90% alcohol-water extract of the stem bark of Uncaria macrophylla. Its structure was elucidated by extensive spectroscopic methods, including 1D and 2D (1H-1H COSY, HSQC and HMBC) NMR and HR-ESI-MS. The cytotoxicities of the compound was evaluated against two cancer cell lines of MCF-7 and HepG2 by the MTT method, and the compound exhibited weak activities with the IC50 values of 78.2 µg/mL and 73.9 µg/mL.
Double N-arylation reaction of polyhalogenated 4,4’-bipyridines. Expedious synthesis of functionalized 2,7-diazacarbazoles
Authors: Abboud Mohamed , Aubert Emmanuel , Mamane Victor
Published: February 2012

Unusual 2,7-diazacarbazoles were prepared in one step from readily available tetra-halogenated 4,4’-bipyridines by using a double N-arylation reaction in the presence of the Pd–XPhos catalyst system. Moderate to good yields were obtained in this site-selective Buchwald–Hartwig double amination. The functionalization of these tricyclic derivatives was performed by using Pd-catalyzed cross-coupling reactions such as the Stille and Suzuki couplings. Two compounds were analyzed by X-ray diffraction and show π–π stacking involving the diazacarbazole moieties and the phenyl rings of functionalized groups.
Influencia fenicia en la arquitectura antigua de Niebla (Huelva)
Authors: Belen María , Escacena Jose Luis
Published: February 2012

Las excavaciones practicadas en Niebla (provincia de Huelva, España) junto a la «Puerta de Sevilla» han descubierto un tell protohistórico sobre el que se asienta la ciudad actual. Dos de los edificios encontrados destacan por sus técnicas de clara inspiración fenicia.
El presente trabajo aborda el estudio tipológico de dichas obras, así como su cronología, enmarcándolas en el contexto de la colonización fenicia del Mediterráneo occidental y reflexionando sobre su significado en los procesos de aculturación experimentados por la Península Ibérica durante la Edad del Hierro.
Espacio y metalurgia en la cultura castreña: la zona arqueológica de Las Médulas
Authors: Fernández-Posse M. Dolores , Montero Ignacio , Sánchez-Palencia F. Javier , Rovira Salvador
Published: February 2012

[es] A partir del análisis espacial de la producción metalúrgica de dos castros prerromanos as tures se establece la existencia de un artesano metalúrgico a tiempo completo, que actúa como suministrador de todo el poblado desde una unidad de ocupación. Se determina su posición social y su desarrollo tecnológico, así como el ámbito de su producción. También se discuten las posibilidades de abastecimiento de materias primas y los fenómenos interactivos dentro del ámbito de la Cultura Castreña del NW.
A modo de contraste, se analiza el cambio que experimenta la producción metalúrgica en dos yacimientos cercanos de época romana cuando la zona ha entrado ya dentro de un nuevo sistema de ocupación, a raíz de la explotación intensiva de sus recursos auríferos.

[fr] L’anayse spatiale de production métallurgique de deux castros préromains astures nous permet de déterminer la présence d'un artisanat métallurgique a plein temps, qui agit comme le fournisseur de la communauté des une «unité d'occupation». Il est égalment possible de determiner sa position sociale et le niveau de developpement technologique, ainsi que le cadre de sa production. Les possibilités d'approvisionnement de matière première et les phenomènes interactifs dans le cadre de la Cultura Castreña du Nord-Ouest de la Péninsule Ibérique sont ensuite discutées.
Comme point de repère nous analysons le changement que subit la production métallurgique dans deux sites archéologiques proches mais appartenant a l’époque romaine, lorsque la zone est déjà integrée dans un nouveau système d’occupation, motivé par I' exploitation de l'or.
Química y arqueología. Propuesta para el estudio de áreas de actividad
Authors: Sánchez Vizcaíno Alberto
Published: February 2012

La aplicación de análisis químicos a las áreas de actividad responde a la necesidad de una precisa definición funcional de tales espacios para la propuesta de conclusiones de tipo social, económico, ideológico, etc. Para cumplir este objetivo se proponen dos fases de análisis complementarias, una experimental y otra puramente arqueológica.
Estudio polínico de cuatro túmulos megalíticos en la cuenca del río Ladra (Lugo, Galicia)
Authors: López Pilar , López J. Antonio
Published: February 2012

En este trabajo se analizan los sedimentos arqueológicos de cuatro túmulos megalíticos, encuadrados cronológicamente, entre el V y el III milenio a. C., situados en la provincia de Lugo. Tras considerar la vegetación actual, se estudian las secuencias obtenidas a partir de los diagramas polínicos, sumándose estos resultados, a los obtenidos por Ramil Rego en 1992 para las sierras septentrionales de esta provincia.
Aproximación teórica y metalográfica a la reducción de hierro en la Prehistoria partiendo del trabajo experimental
Authors: Sarabia Herrero Francisco Javier
Published: February 2012

El presente artículo describe una experiencia de reducción de hierro realizada en Dinamarca en una reproducción de horno vertical basada en hallazgos datados en la II Edad del Hierro danesa. Igualmente, se realiza un encuadre teórico de dicha experiencia, tanto desde el punto de vista químico como del arqueológico, y se incluye un examen metalográfico del hierro obtenido cara a su posible utilización en la investigación de piezas históricas de hierro.
Los santuarios ibéricos. Apuntes para el desarrollo de una Arqueología del Culto
Authors: Prados Torreira Lourdes
Published: February 2012

Se estudian las características específicas de los principales lugares de culto del área ibérica, haciendo hincapié en su emplazamiento y en su relación con el territorio. Se apunta una serie de rasgos comunes a algunos santuarios como su función religiosa, económica y política.
Tecnología de herramientas rotativas durante el Bronce Final Atlántico. El depósito de Villena
Authors: Armbruster Barbara R. , Perea Alicia
Published: February 2012

El estudio de los brazaletes del tesoro de Villena es el punto de partida de una investigación en equipo que ha tenido como resultado la constatación de un estadio tecnológico más avanzado del que hasta ahora se pensaba para la metalurgia del Bronce Atlántico en la Península Ibérica. Se demuestra la práctica de una sofisticada técnica de fundición a la cera perdida en oro y la existencia del torno de eje horizontal. Finalmente planteamos un modelo interpretativo para este importante depósito y situamos en un marco de cronología relativa toda una serie de hallazgos de orfebrería del suroeste peninsular que hasta la fecha se encontraban descontextualizados.
La Venus de Gavà (Barcelona). Una aportación fundamental para el estudio de la religión neolítica del suroeste europeo
Authors: Bosch Argilagós Josep , Estrada Martín Alicia
Published: February 2012

Las excavaciones arqueológicas en las Minas Prehistóricas de Gava (Barcelona), explotadas durante el neolítico, han puesto al descubierto recientemente en el interior de uno de sus pozos la Venus de Gava. Es una figura antropomorfa femenina de cerámica, sobre la que se han dibujado las partes del cuerpo y su ornamentación mediante decoración en relieve y esgrafiada con pintura blanca incrustada. Es la única figura humana del Neolítico de la Península Ibérica con una morfología y motivos decorativos que permiten suponerle un valor religioso relacionado con el culto a la diosa de la fertilidad.
Arqueología y política: el desarrollo de la arqueología española en su contexto histórico
Authors: Díaz-Andreu Margarita , Mora Gloria
Published: February 2012

En este artículo se ofrecen unas notas para una historia de la arqueología española en los siglos XVIII, XIX y XX. Hemos elegido como eje de la exposición la relación entre el desarrollo de la arqueología y los intereses políticos que caracterizaron cada momento histórico. España se halla inmersa dentro de un contexto europeo y, como en los demás países, la arqueología se ha visto mediatizada por los cambios de régimen a lo largo de las tres últimas centurias. Desde su uso por parte de la monarquía como medio de legitimar sus prerrogativas en el siglo XVIII, la influencia que en ella ejerce la emergencia de los nacionalismos en el XIX y su plasmación en la creación de instituciones, y las distintas visicitudes políticas de este siglo, en todas las épocas se constata la poco explícita pero indudable relación entre arqueología y poder.
Aproximación al estudio del vidrio prerromano: los materiales procedentes de la necrópolis ibérica de El Cigarralejo (Mula, Murcia). Composición química de varias cuentas de collar
Authors: Ruano Ruiz Encarnación , Hoffman P. , Rincón J. M.
Published: February 2012

El texto agrupa por primera vez todos los materiales de vidrio procedentes de las excavaciones de la necrópolis ibérica de El Cigarralejo (Mula, Murcia), tanto de las tumbas publicadas, como inéditas. El escaso número de objetos de vidrio en los ajuares de la necrópolis murciana permite considerarlos como adornos de prestigio y en algún caso con fines profilácticos. Sólo como hipótesis debemos considerar la existencia de un taller cercano al área estudiada. Se presenta la composición química de algunas cuentas de collar.
La etnoarqueología, hoy: Una vía eficaz de aproximación al pasado
Authors: Hernando Gonzalo Almudena
Published: February 2012

Definir los contenidos, objetivos y metodología de la Etnoarqueología constituye una difícil tarea. Aunque el término había sido utilizado con anterioridad, su nacimiento como disciplina o heurística para el conocimiento del pasado se corresponde con el de la Nueva Arqueología americana, en tanto que una de sus Teorías de Alcance Medio. Como tal, implicaba toda una serie de asunciones teóricas rebatidas posteriormente por la corriente post-procesual. Ambas posiciones teóricas defienden modelos opuestos de concebir la Etnoarqueología, a la vez que ésta es confundida a menudo con la «Arqueología viva» o con la analogía etnográfica.
La propuesta de estas páginas es doble: por un lado, se intentará clarificar el alcance y la especificidad de la Etnoarqueología frente a otras heurísticas desde una argumentación exclusivamente teórica; por otro, se planteará un caso concreto para ejemplificar las nuevas vías de aproximación al pasado que hoy ofrece la Etnoarqueología.
El registro paleoclimático pleistoceno en la evolución del karst de Atapuerca (Burgos): El corte de gran dolina
Authors: Hoyos Manuel , Aguirre Emiliano
Published: February 2012

Se analizan las características sedimentológicas de los niveles del corte de Gran Dolina (TD) en la Trinchera de Atapuerca (Burgos) y el clima que se deduce. referenciando el contenido faunístico y arqueológico de cada nivel. Se indican las bases para la datación geocronométrica, así como la correlación de las fluctuaciones climáticas inferidas en Gran Dolina con los episodios O18 del océano, contrastando aquéllas con evidencias paleontológicas. Se consideran en particular las fluctuaciones en la humedad y régimen pluvial.
Indicadores químicos de combustión en un hogar del Paleolítico Medio del yacimiento de Mediona I (Alt Penedès, Barcelona)
Authors: Lozano Joan Miquel , Simó Rafel , Grimalt Joan O. , Estévez Jordi
Published: February 2012

La aplicación del análisis químico orgánico a muestras arqueológicas es una técnica de desarrollo reciente. El estudio de la fracción lipídica (eso es, la fracción de materia extraíble mediante disolventes orgánicos) de restos sedimentarios en yacimientos permite recuperar una información inaccesible a otras técnicas de identificación aplicadas a la Arqueología. Este artículo describe de forma comparativa la fracción aromática del sedimento en el interior y en el exterior de un área de combustión en un yacimiento paleolítico previamente excavado.
Asimismo, presenta el análisis de indicadores químicos pirogénicos con una técnica de gran potencial para la identificación de áreas de combustión en yacimientos donde éstos no están claramente definidos (simples manchas sin carbones, agrupación de piedras sin evidencias externas de termo alteración, etc.), siempre comparándolas con muestras de sedimento no termo alterado del mismo nivel arqueológico.
Minería neolítica en Gavá (Baix Llobregat, Barcelona)
Authors: Bosch Argilagós Josep , Estrada Martín Alicia , Noain Maura María José
Published: February 2012

A partir de los resultados de la excavación arqueológica, del estudio geológico y de la experimentación se plantean los procesos del trabajo minero y de la variscita durante el Neolítico Antiguo Evolucionado y el Neolítico Medio en Gavá. Se analizan: las estructuras de explotación, con diferencias formales y de distribución entre un período y otro; los utensilios mineros, con variaciones materiales, formales y funcionales; los productos extraídos, identificándose únicamente la variscita; la elaboración de cuentas de variscita realizada en el mismo yacimiento; el contexto económico y social de estos procesos de trabajo, no aceptando una especialización de las comunidades neolíticas de Gavá en la minería y en la elaboración de cuentas; y los aspectos ideológicos ligados a la minería, proponiendo una unión con los de la agricultura y la ganadería.
Enterramientos y diferenciación social II. La problemática de la Edad del Bronce en el Alto Guadalquivir
Authors: Cámara Serrano Juan Antonio , Contreras Cortés Francisco , Pérez Bareas Cristóbal , Lizcano Prestel Rafael
Published: February 2012

Se plantea aquí la relación del ritual de enterramiento con la reproducción social prestando especial atención a las inhumaciones de la Edad del Bronce del Sur de la Península Ibérica, así como a los mecanismos de herencia a los que pueden estar vinculados. También se discute el papel de la apropiación de los rebaños en la jerarquización social y el carácter servil y aristocrático de esas sociedades. Por último, se encontrarán algunas reflexiones sobre los límites de lo que llamamos "Horizonte Argárico" y las causas de la expansión de los rasgos de cultura material que lo definen.