bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of Reynolds number on the dynamics and wakes of freely rising and falling spheres
Authors: HOROWITZ M. , WILLIAMSON C. H. K. 
Published: March 2010

In this paper, we study the effect of the Reynolds number (Re) on the dynamics and vortex formation modes of spheres rising or falling freely through a fluid (whereRe= 100–15000). Since the oscillation of freely falling spheres was first reported by Newton (University of California Press, 3rd edn, 1726, translated in 1999), the fundamental question of whether a sphere will vibrate, as it rises or falls, has been the subject of a number of investigations, and it is clear that the mass ratiom* (defined as the relative density of the sphere compared to the fluid) is an important parameter to define when vibration occurs. Although all rising spheres (m* < 1) were previously found to oscillate, either chaotically or in a periodic zigzag motion or even to follow helical trajectories, there is no consensus regarding precise values of the mass ratio (m*crit) separating vibrating and rectilinear regimes. There is also a large scatter in measurements of sphere drag in both the vibrating and rectilinear regimes.In our experiments, we employ spheres with 133 combinations ofm* andRe, to provide a comprehensive study of the sphere dynamics and vortex wakes occurring over a wide range of Reynolds numbers. We find that falling spheres (m* > 1) always move without vibration. However, in contrast with previous studies, we discover that a whole regime of buoyant spheres rise through a fluid without vibration. It is only when one passes below a critical value of the mass ratio, that the sphere suddenly begins to vibrate periodically and vigorously in a zigzag trajectory within a vertical plane. The critical mass is nearly constant over two ranges of Reynolds number (m*crit≈ 0.4 forRe= 260–1550 andm*crit≈ 0.6 forRe> 1550). We do not observe helical or spiral trajectories, or indeed chaotic types of trajectory, unless the experiments are conducted in disturbed background fluid. The wakes for spheres moving rectilinearly are comparable with wakes of non-vibrating spheres. We find that these wakes comprise single-sided and double-sided periodic sequences of vortex rings, which we define as the ‘R’ and ‘2R’ modes. However, in the zigzag regime, we discover a new ‘4R’ mode, in which four vortex rings are created per cycle of oscillation. We find a number of changes to occur at a Reynolds number of 1550, and we suggest the possibility of a resonance between the shear layer instability and the vortex shedding (loop) instability. From this study, ensuring minimal background disturbances, we have been able to present a new regime map of dynamics and vortex wake modes as a function of the mass ratio and Reynolds number {m*,Re}, as well as a reasonable collapse of the drag measurements, as a function ofRe, onto principally two curves, one for the vibrating regime and one for the rectilinear trajectories.
Race/ethnic differences in exposure to traumatic events, development of post-traumatic stress disorder, and treatment-seeking for post-traumatic stress disorder in the United States
Authors: Roberts A. L. , Gilman S. E. , Breslau J. , Breslau N. , Koenen K. C. 
Published: March 2010

BackgroundTo identify sources of race/ethnic differences related to post-traumatic stress disorder (PTSD), we compared trauma exposure, risk for PTSD among those exposed to trauma, and treatment-seeking among Whites, Blacks, Hispanics and Asians in the US general population.MethodData from structured diagnostic interviews with 34 653 adult respondents to the 2004–2005 wave of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were analysed.ResultsThe lifetime prevalence of PTSD was highest among Blacks (8.7%), intermediate among Hispanics and Whites (7.0% and 7.4%) and lowest among Asians (4.0%). Differences in risk for trauma varied by type of event. Whites were more likely than the other groups to have any trauma, to learn of a trauma to someone close, and to learn of an unexpected death, but Blacks and Hispanics had higher risk of child maltreatment, chiefly witnessing domestic violence, and Asians, Black men, and Hispanic women had higher risk of war-related events than Whites. Among those exposed to trauma, PTSD risk was slightly higher among Blacks [adjusted odds ratio (aOR) 1.22] and lower among Asians (aOR 0.67) compared with Whites, after adjustment for characteristics of trauma exposure. All minority groups were less likely to seek treatment for PTSD than Whites (aOR range: 0.39–0.61), and fewer than half of minorities with PTSD sought treatment (range: 32.7–42.0%).ConclusionsWhen PTSD affects US race/ethnic minorities, it is usually untreated. Large disparities in treatment indicate a need for investment in accessible and culturally sensitive treatment options.
Developmental trajectories of psychotic-like experiences across adolescence: impact of victimization and substance use
Authors: Mackie C. J. , Castellanos-Ryan N. , Conrod P. J. 
Published: March 2010

BackgroundResearch suggests that psychotic-like experiences (PLEs) in the general population are common, but can reflect either transitory or persistent developmental phenomena. Using a general adolescent population it was examined whether different developmental subtypes of PLEs exist and whether different trajectories of PLEs are associated with certain environmental risk factors, such as victimization and substance use.MethodSelf-reported PLEs were collected from 409 adolescents (mean age 14 years 7 months) at four time points, each 6 months apart. General growth mixture modelling was utilized to identify classes of adolescents who followed distinct trajectories of PLEs across this period. Predictors of class membership included demographics, personality, victimization, depression, anxiety and substance use.ResultsWe identified the following three developmental subgroups of PLEs: (1) persistent; (2) increasing; (3) low. Adolescents on the persistent trajectory reported frequent victimization and consistent elevated scores in depression and anxiety. Adolescents on the increasing trajectory were engaging in cigarette use prior to any increases in PLEs and were engaging in cocaine, cannabis and other drug use as PLEs increased at later time points.ConclusionsThe findings suggest that different developmental subgroups of PLEs exist in adolescence and are differentially related to victimization and substance use.
Frank Tannenbaum and the Mexican Revolution
Authors: Knight Alan 
Published: March 2010

AbstractThis article examines Frank Tannenbaum's engagement with Mexico in the crucial years following the Revolution of 1910–1920 and his first visit to the country in 1922. Invited—and feted—by the government and its powerful labor allies, Tannenbaum soon expanded his initial interest in organized labor and produced a stream of work dealing with trade unions, peasants, Indians, politics, and education—work that described and often justified the social program of the Revolution, and that, rather surprisingly, continued long after the Revolution had lost its radical credentials in the 1940s. Tannenbaum's vision of Mexico was culturalist, even essentialist; more Veblenian than Marxist; at times downright folkloric. But he also captured important aspects of the process he witnessed: local and regional variations, the unquantifiable socio-psychological consequences of revolution, and the prevailing concern for order and stability. In sum, Tannenbaum helped establish the orthodox—agrarian, patriotic, and populist—vision of the Revolution for which he has been roundly, if sometimes excessively, criticized by recent “revisionist” historians; yet his culturalist approach, with its lapses into essentialism, oddly prefigures the “new cultural history” that many of these same historians espouse.
Termite diversity and abundance across fire-induced habitat variability in a tropical moist savanna (Lamto, Central Côte d'Ivoire)
Authors: Dosso Kanvaly , Konaté Souleymane , Aidara Daouda , Linsenmair K. E. 
Published: March 2010

Abstract:At Lamto, little is known about animal community responses to habitat variability resulting from fires and the mosaic pattern of the vegetation in general and in particular about that of termites which play key roles in this ecosystem. With a standardized method, data were collected on termites from four habitats differing in their vegetation cover and fire-history: annually burned savanna, savanna woodland, forest island and gallery forest. A range of environmental variables was measured and correlated with species abundances. The number of termite species collected in the savanna woodland was very close to that found in the gallery forest while the forest island was the richest habitat. The species richness of the savanna woodland and forest island seemed partly due to their heterogeneous and transitional vegetation structures and variable food resources. With regard to the fire-history of habitats, Connell's intermediate disturbance hypothesis offers an explanation for differences in the patterns of habitat-specific species richness. Variation in species abundances was significantly correlated with only two environmental variables (soil pH and woody plant species richness). The pH appeared as the most influential factor for fungus-growers while tree invasion in the savanna strongly reduces the abundance of grass-feeding species (e.g. Trinervitermes geminatus). Although not significantly correlated with species abundances, soil carbon showed a positive correlation with the dominant soil-feeder Basidentitermes potens. As for wood-feeders, they were not strongly correlated with woody plant species richness; this fact might be linked to their use for other sources of nourishment. Overall, it appears that habitat variability in the Lamto reserve contributes to the maintenance of different subsets of the termite community.
Estimation of root biomass based on excavation of individual root systems in a primary dipterocarp forest in Pasoh Forest Reserve, Peninsular Malaysia
Authors: Niiyama Kaoru , Kajimoto Takuya , Matsuura Yojiro , Yamashita Tamon , Matsuo Naoko , Yashiro Yuichiro , Ripin Azizi , Kassim Abd. Rahman , Noor Nur Supardi 
Published: March 2010

Abstract:Precise estimation of root biomass is important for understanding carbon stocks and dynamics in tropical rain forests. However, limited information is available on individual root masses, especially large trees. We excavated 121 root systems of various species (78) and sizes (up to 116 cm in dbh), and estimated both above- and below-ground biomass in a lowland primary dipterocarp forest in the Pasoh Forest Reserve, Peninsular Malaysia. A tree census was conducted in four research plots (each 0.2 ha) and stand-level biomass was estimated. We examined relationships between tree size parameters and masses of coarse roots (roots ≥5 mm in diameter) and derived a dbh-based allometric equation. The amounts of coarse roots that were lost during excavation were corrected. Coarse-root biomass before and after correction for lost roots was estimated to be 63.8 and 82.7 Mg ha−1, indicating that significant amounts of roots (23%) were lost during the sampling. We also estimated the biomass of small root (<5 mm) by applying pipe-model theory. The estimate, 13.3 Mg ha−1, was similar to another estimate of small roots, 16.4 Mg ha−1, which was obtained directly by the soil-pit sampling method. Total below-ground (BGB) and above-ground biomass (AGB) was estimated to be 95.9 and 536 Mg ha−1, respectively. The biomass-partitioning ratio (BGB/AGB) was about 0.18. In conclusion, the dbh-based allometric equation for coarse roots developed in this study, which kept good linearity even including the data of larger trees, might be useful for evaluating below-ground carbon stocks in other stands of similar forest (old-growth dipterocarp) in South-East Asia.
Temporal separation between jaguar and puma in the dry forests of southern Bolivia
Authors: Romero-Muñoz Alfredo , Maffei Leonardo , Cuéllar Erika , Noss Andrew J. 
Published: March 2010

Abstract:Despite the potential importance of temporal separation for the coexistence of competing species, no study has found significant segregation at the circadian level between jaguar (Panthera onca) and puma (Puma concolor) in sympatry. Using data from camera trap surveys (wet and dry seasons), we have evaluated the activity patterns of both species and their potential prey at four areas in the dry forest of the Bolivian Chaco. We tested if temporal separation existed between these two species, and if their activity was related to that of a particular prey. At most sites, activity patterns of jaguar and puma did not vary significantly between seasons, except for puma at one site. There were no differences between sexes for any cat species at any site. At three sites we found statistically significant differences in the activity patterns of jaguar and puma, as they showed a clear temporal segregation. None of them followed the activity patterns of any particular prey species across sites. The latter suggests that segregation is influenced by avoidance behaviour between the two felid species. Therefore, temporal separation may be an important behavioural factor promoting the coexistence of jaguar and puma in some areas of this dry forest.
Polarized-Light Interferometry of Calcium Carbonate Deposition in Moss from a Waterfall on the Niagara Escarpment
Authors: Swatland Howard J. 
Published: March 2010

AbstractDeposition of calcium carbonate from groundwater was examined on a moss, Didymodon tophaceus, from a Niagara Escarpment waterfall. A spectrophotometer on a polarizing microscope was used for interferometry. A second-order blue interference with an interference minimum around 620 nm was found when moss cell spaces were fully calcified. Filled cell spaces were often surrounded by empty cell spaces. Complete calcification of whole leaflets resulted in progressively higher orders of interference colors and a positive shift in interference minima. Calcified leaflets finally became cemented together, but each retained a weak extinction when rotated. Small calcareous spherulites (mean diameter 15.7 ± 2.1 μm) were found between leaflets. Spherulites exhibited first-order white interference with a Maltese cross that rotated when the polarizer and analyzer were rotated in tandem. A Nikitin-Berek compensator was tilted at 5.5° to give an interference minimum at 600 nm in the optical axis. Quadrants of spherulites with radii more or less in line with the tilting axis of the compensator had lower (P < 0.001) interference minima (535 ± 27 nm) than quadrants with radii more or less perpendicular to the compensator (659 ± 15 nm), thus indicating a radial internal structure. Spherulites were tentatively identified as vaterite.
Global benefits, local burdens? The paradox of governing biofuels production in Kansas and Iowa
Authors: Selfa Theresa 
Published: March 2010

AbstractRecent sociological analysis of the expansion of the biofuels industry internationally has noted the paradox between the purported global environmental benefits of reducing greenhouse gas emissions by replacing fossil fuels with biofuels, and the potential for distinctly negative environmental impacts experienced at local sites of biofuels production. The state, in both the USA and the EU, has played a prominent role in promoting the development and expansion of biofuels production through government mandates and incentives, but the state's role in governing the potentially (negative) economic, social or environmental impacts of biofuels production on local communities has been much more limited in scope. We review the environmental sociological literature to frame analysis of how the state is governing the benefits and burdens brought by the ethanol industry to rural communities in Kansas and Iowa. Drawing on data from community surveys, focus group and individual interviews and analysis of environmental violations, the paper examines the local impacts of biofuels production in three case-study communities. Findings suggest that local residents do not express many concerns about environmental impacts and that the state has played a modest role in governing the negative local environmental impacts. We argue that this lack of concern is related to the histories of these rural communities, which have long depended on resource extractive industries and currently are desperate for economic growth. We find that criticisms of negative environmental impacts are muted in relation to purported economic benefits and to other comparable industries. These community case studies illustrate some of the challenges, both at the practical and theoretical levels, of governing biofuels production.
HMGA1a induces aberrant splicing of estrogen receptor α in MCF-7 breast cancer cells
Authors: Ohe Kenji , Utsumi Toshiaki , Mayeda Akila 
Published: March 2010

AbstractThe well known transcription factor, HMGA1a, also known as an oncogene, causes aberrant splicing of Presenilin-2 found in sporadic Alzheimer's disease, through sequence specific RNA binding. Since HMGA1 protein levels correlate with tumorigenic malignancy, we are interested in the potential of HMGA1a as an aberrant splicing factor in cancer. The N-terminal truncated isoform of Estrogen Receptor alpha, ERα46, is known to increase expression when breast cancer cells (MCF-7) become hyperconfluent. Transiently expressed HMGA1a induced ERα46 mRNA expression. Plasmid driven micro RNA containing the presenilin-2 HMGA1a RNA binding site and a micro RNA nuclear localization signal (miRHMGBSNLS), inhibited ERα46 mRNA expression, acting as a decoy. Re-expressing HMGA1a restored ERα46 mRNA expression. An HMGA1a binding site was found in the skipped exon 1A, 33 bp upstream the authentic 5’ splice site, adjacent a pseudo 5’ splice site. RNA gel shift assay showed binding of HMGA1a to this site. Exon skipping by HMGA1a and exon inclusion by the HMGA1a binding site decoy could be reproduced in vitro in a heterologous context. Psoralen UV crosslinking showed HMGA1a anchored U1 snRNP to the upstream pseudo 5’ splice site. Psoralen UV crosslinking combined with antisense DNA oligo / RNaseH protection comfirmed U1 snRNP anchored to the upstream pseudo 5’ splice site by HMGA1a. This is the second example of the PSI model found in Drosophila, but the first in human. Finally, the stable transfectant of the decoy, miRHMGBSNLS (MCF-7 cells), which shows decreased ERα46 protein level, was prone to apoptosis by high dose estrogen. We hope this decoy, miR_HMGBS_NLS, in combination with high dose estrogen, will lead to development of a novel breast cancer therapy, an alternative of conventional estrogen deprivation.
Measurement of red blood cell mechanics during morphological changes
Authors: Park YongKeun , Best Catherine A. , Badizadegan Kamran , Dasari Ramachandra R. , Feld Michael S. , Kuriabova Tatiana , Henle Mark L. , Levine Alex J. , Popescu Gabriel 
Published: March 2010

The human red blood cell (RBC) membrane, a fluid lipid bilayer tethered to an elastic 2D spectrin network, provides the principal control of the cell’s morphology and mechanics. These properties, in turn, influence the ability of RBCs to transport oxygen in circulation. Current mechanical measurements of RBCs rely on external loads. Here we apply a noncontact optical interferometric technique to quantify the thermal fluctuations of RBC membranes with 3 nm accuracy over a broad range of spatial and temporal frequencies. Combining this technique with a new mathematical model describing RBC membrane undulations, we measure the mechanical changes of RBCs as they undergo a transition from the normal discoid shape to the abnormal echinocyte and spherical shapes. These measurements indicate that, coincident with this morphological transition, there is a significant increase in the membrane’s shear, area, and bending moduli. This mechanical transition can alter cell circulation and impede oxygen delivery.
Structural basis for solute transport, nucleotide regulation, and immunological recognition of
Neisseria meningitidis
PorB
Authors: Tanabe Mikio , Nimigean Crina M. , Iverson T. M. 
Published: March 2010

PorB is the second most prevalent outer membrane protein in
Neisseria meningitidis
. PorB is required for neisserial pathogenesis and can elicit a Toll-like receptor mediated host immune response. Here, the x-ray crystal structure of PorB has been determined to 2.3 Å resolution. Structural analysis and cocrystallization studies identify three putative solute translocation pathways through the channel pore: One pathway transports anions nonselectively, one transports cations nonselectively, and one facilitates the specific uptake of sugars. During infection, PorB likely binds host mitochondrial ATP, and cocrystallization with the ATP analog AMP–PNP suggests that binding of nucleotides regulates these translocation pathways both by partial occlusion of the pore and by restricting the motion of a putative voltage gating loop. PorB is located on the surface of
N. meningitidis
and can be recognized by receptors of the host innate immune system. Features of PorB suggest that Toll-like receptor mediated recognition outer membrane proteins may be initiated with a nonspecific electrostatic attraction.
Vicinal dihalonium ions: diprotonated and dimethylated chlorine [H2Cl22+, (CH3)2Cl22+] and bromine [H2Br22+, (CH3)2Br22+] dications
Authors: Olah George A. , Surya Prakash G. K. , Rasul Golam 
Published: March 2010

High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of superelectrophilic diprotonated, and dimethylated molecular chlorine (

Cl
2

) and bromine (

Br
2

) dications. Diprotonated chlorine and diprotonated bromine dications
3a
and
6a
, respectively, were found to be lowest energy minima. The isomeric dications,
3b
and
6b
, are also minima on the potential energy surfaces but they are significantly less stable than the structures
3a
and
6a
by 33.6 and 30.9 kcal/mol, respectively. On the basis of computed G2 energies, proton affinities and related thermodynamic parameters were also calculated. Dications
3a
and
6a
have substantial kinetic barriers for deprotonation. Their homolytic dissociation are however facile. Dimethylated molecular chlorine and bromine dications
3g
and
6g
, respectively, were also found to be global energy minima. These vicinal dihalonium or the corresponding protosolvated species are expected to form either in the superacidic media or in the gas phase.