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During the past three decades worldwide dairy policies have been implemented to promote the consumption of milk and milk products in urban areas and the production from rural areas close to big cities (Alderman et al., 1987). Bolivia and the city of Santa Cruz de la Sierra have been influenced by these worldwide directives and this current study examines the impact of policies on the demand and supply side of the sector, but with particular emphasis on smallholder milk producers and poor urban consumers. The current research is part of a multi-country study on the supply, demand and impact of dairy and other policies over a 10 to 15 year period (1985 to 2000) of the milk sectors of Santa Cruz, Bolivia; Nairobi, Kenya; and Kathmandu, Nepal.
This work shows the electrochemical study of nickel (Ni) and TiC/Ni composite immersed in synthetic seawater. In order to characterize the corrosion process, polarization curves (PC) were carried out. All electrochemical measures were made under static conditions, room temperature, atmospheric pressure and 24 hours exposure time. An electrochemical cell with a typical three-electrode array was used. Effect of TiC as reinforcement into the Ni matrix was evaluated. According PC results, it is possible to point out that the corrosion rate (CR) of the TiC/Ni composite was higher than Ni corrosion rate. The obtained results indicate that the corrosion process of both materials is of mixed type, that is to say a process of transfer of load influenced by a mechanism of mass transfer. Observations through scanning electron microscopy (SEM) revealed that mechanism of corrosion was cells of differential aeration (difference of concentration of oxygen). The corrosion morphology was localized type (pits and crevice).
The chronology of the Inca Empire has traditionally relied on ethnohistoric dates, which suggest that a northern expansion into modern Ecuador began in AD 1463 and a southern expansion into modern Argentina began in AD 1471. We test the validity of these dates with two Bayesian models, which show that the ethnohistoric dates are incorrect and that the southern expansion began before the northern one. The first model of seven dates shows that the site of Chamical, Ecuador, was first occupied cal AD 1410–1480 (95% probability) and has a high probability of being built prior to the ethnohistoric date. The second is an outlier model of 26 14C dates and 19 thermoluminescence (TL) dates from 10 sites along the empire’s southeastern limit in northwestern Mendoza, Argentina. Here, the Inca occupation began cal AD 1350–1440 (95% probability), also earlier than the ethnohistoric date. The model also suggests that the Inca occupation of Mendoza lasted 70–230 yr (95% probability), longer than previously thought, which calls for new perspectives on the timing and nature of Inca conquests and relationships with local groups. Based on these results, we argue it is time to abandon the traditional chronology in favor of Inca chronologies based on Bayesian models.
The perspective of statistical state dynamics (SSD) has recently been applied to the study of mechanisms underlying turbulence in a variety of physical systems. An SSD is a dynamical system that evolves a representation of the statistical state of the system. An example of an SSD is the second-order cumulant closure referred to as stochastic structural stability theory (S3T), which has provided insight into the dynamics of wall turbulence, and specifically the emergence and maintenance of the roll/streak structure. S3T comprises a coupled set of equations for the streamwise mean and perturbation covariance, in which nonlinear interactions among the perturbations has been removed, restricting nonlinearity in the dynamics to that of the mean equation and the interaction between the mean and perturbation covariance. In this work, this quasi-linear restriction of the dynamics is used to study the structure and dynamics of turbulence in plane Poiseuille flow at moderately high Reynolds numbers in a closely related dynamical system, referred to as the restricted nonlinear (RNL) system. Simulations using this RNL system reveal that the essential features of wall-turbulence dynamics are retained. Consistent with previous analyses based on the S3T version of SSD, the RNL system spontaneously limits the support of its turbulence to a small set of streamwise Fourier components, giving rise to a naturally minimal representation of its turbulence dynamics. Although greatly simplified, this RNL turbulence exhibits natural-looking structures and statistics, albeit with quantitative differences from those in direct numerical simulations (DNS) of the full equations. Surprisingly, even when further truncation of the perturbation support to a single streamwise component is imposed, the RNL system continues to self-sustain turbulence with qualitatively realistic structure and dynamic properties. RNL turbulence at the Reynolds numbers studied is dominated by the roll/streak structure in the buffer layer and similar very large-scale structure (VLSM) in the outer layer. In this work, diagnostics of the structure, spectrum and energetics of RNL and DNS turbulence are used to demonstrate that the roll/streak dynamics supporting the turbulence in the buffer and logarithmic layer is essentially similar in RNL and DNS.
The invariants of the velocity gradient tensor,
, and their enstrophy and strain components are studied in the logarithmic layer of an incompressible turbulent channel flow. The velocities are filtered in the three spatial directions and the results are analysed at different scales. We show that the
plane does not capture the changes undergone by the flow as the filter width increases, and that the enstrophy/enstrophy-production and strain/strain-production planes represent better choices. We also show that the conditional mean trajectories may differ significantly from the instantaneous behaviour of the flow since they are the result of an averaging process where the mean is 3–5 times smaller than the corresponding standard deviation. The orbital periods in the
plane are shown to be independent of the intensity of the events, and of the same order of magnitude as those in the enstrophy/enstrophy-production and strain/strain-production planes. Our final goal is to test whether the dynamics of the flow is self-similar in the inertial range, and the answer turns out to be that it is not. The mean shear is found to be responsible for the absence of self-similarity and progressively controls the dynamics of the eddies observed as the filter width increases. However, a self-similar behaviour emerges when the calculations are repeated for the fluctuating velocity gradient tensor. Finally, the turbulent cascade in terms of vortex stretching is considered by computing the alignment of the vorticity at a given scale with the strain at a different one. These results generally support a non-negligible role of the phenomenological energy-cascade model formulated in terms of vortex stretching.
This article provides a thematic overview of a subset of controversial officer involved shootings that have occurred in Denver, Colorado during a period of thirty years (1983-2012). Determining whether a shooting was legally justified involved multiple participants, including local, national, and international representatives. The primary stakeholders were City and County District Attorneys regarding whether to file criminal charges against the officer, and Managers of Safety for whether officers acted within police departmental policy. Although most cases were processed without conflict, a small number were challenged by members of the community based on thematic reasons of shooting individuals who had not committed a crime, violating continuum of force standards, and entrusting law enforcement officers with the power to use deadly force both off-duty and while working secondary jobs. Despite outcome legitimacy vested in a small number of public officials, community members often reported a lack of justice and accountability. They struggled to get public officials to take notice and implement systematic change. Reviewing controversial shootings highlights the multiple issues involved in protecting law enforcement officers from encountering criminal charges, and in essence the procurement of colonial control. Critical Race Theory (interest convergence and storytelling), Social Dominance Theory, along with the historical framework of W. E. B. Du Bois, were utilized to explore a number of officer-involved shootings that continue to produce disparate outcomes by race, class, and gender.
Carbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from diethyl ether, butanol, hexane and ethyl acetate. A quartz tube with a stainless steel tube catalyst core with 0.019 m diameter and 0.6 m large formed the reactor. To avoid combustion, argon was used as the carrier gas. Time process ranged 30 to 60 min. The range of CNTs synthesis temperature was 680-850 °C for different precursors. Scanning Electron Microscopy micrographs have demonstrated tangled CNTs growth in all samples, thus presenting difficult length measurement. The CNTs diameters from diethyl ether are 45-200 nm, butanol diameter range from 55-230 nm, hexane diameter range is 50-130 nm and ethyl acetate range from 100 to 300 nm. Carbon content for all samples was higher than 93 %, CNTs from butanol showed carbon concentration up to 99%. FTIR, Raman and X-Ray Spectroscopies spectra for all samples demonstrated the characteristics signals present in carbon nanotubes. This research proposes a simple, effective and innovative method to synthesize CNTs by CVD on iron stainless steel catalyst in combination with diethyl ether, ethyl acetate, butanol and hexane as precursors by applying the principles of green chemistry, sustainability and its ease to be scaled.
In a 1-year survey at a university hospital we found that 20·6% (81/392) of patients with antibiotic associated diarrohea where positive for C. difficile. The most common PCR ribotypes were 012 (14·8%), 027 (12·3%), 046 (12·3%) and 014/020 (9·9). The incidence rate was 2·6 cases of C. difficile infection for every 1000 outpatients.
Year 2 findings are reported from a longitudinal, experimental-control study involving 31 Spanish-speaking preschoolers (aged 38–48 months) randomly assigned to two Head Start classrooms. In Year 1, classrooms differed only in the language of instruction, with teachers using only Spanish in one classroom and only English in the other. In Year 2, an experimental transitional bilingual education (TBE) model was implemented, with English being gradually introduced in the TBE classroom until a ratio of 30:70 English-to-Spanish was achieved and Spanish being gradually introduced in the predominantly English (PE) classroom until a ratio of 70:30 English-to-Spanish was achieved. Year 2 results were consistent with Year 1, with the TBE classroom exceeding the PE classroom on all Spanish measures of language and literacy development and no significant differences favoring the PE classroom. Results also indicated that Year 2 trajectories were conditional on first-year effects, suggesting that sustained growth in dual language learner's early literacy may depend on early intervention among 3-year-old preschoolers.
We study the flow under gravity of a granular model system submitted to shear in a rotating cylinder. The system is confined in a vertical 2D geometry which allows visualisation of the bulk and direct measurements of the velocity and density fields. We establish the existence of scaling properties displayed by velocity and density profiles for a large range ofdifferent flow rates.
We study granular materials using both event driven (ED) and molecular dynamics (MD) methods. In the MD simulations we implement linear as well as nonlinear forces and also hysteretic interactions. For multiple collisions the two methods show differences: MD calculations lead to weak, whereas ED methods result in rather strong dissipation, as determined through an effective restitution coefficient.
We report an experimental study of the ascent of a large disc imbedded in a 2D packing ofsmall beads vertically vibrated. Two distinct mechanisms leading to size segregation are observed in situ. At high acceleration, the convection process associated with surface trapping is predominates. At low acceleration, we examine the effect of the size ratio on the dynamics of the segregation which is either intermittent or continuous. This isdue to the successive formation and destruction of arches.
To compare BMI with abdominal skinfold thickness (ASF), waist circumference and waist-to-height ratio in the prediction of insulin resistance (IR) in prepubertal Colombian children.
We calculated age- and sex-specific Z-scores for BMI, ASF, waist circumference, waist-to-height ratio and three other skinfold-thickness sites. Logistic regression with stepwise selection (P = 0·80 for entry and P = 0·05 for retention) was performed to identify predictors of IR and extreme IR, which were determined by age- and sex-specific Z-scores to identify the ≥ 90th and ≥ 95th percentile of homeostasis model assessment (HOMAIR), respectively. We used receiver operating characteristic curves to compare the area under the curve between models.
Children (n 1261) aged 6–10 years in Tanner stage 1 from a population-based study.
A total of 127 children (seventy girls and fifty-seven boys) were classified with IR, including sixty-three children (thirty-three girls and thirty boys) classified with extreme IR. Only ASF and BMI Z-scores were retained as predictors of IR by stepwise selection. Adding ASF Z-score to BMI Z-score improved the area under the curve from 0·794 (95 % CI 0·752, 0·837) to 0·811 (95 % CI 0·770, 0·851; P for contrast = 0·01). In predicting extreme IR, the addition of ASF Z-score to BMI Z-score improved the area under the curve from 0·837 (95 % CI 0·790, 0·884) to 0·864 (95 % CI 0·823, 0·905; P for contrast = 0·01).
ASF Z-score predicted IR independent of BMI Z-score in our population of prepubertal children. ASF and BMI Z-scores together improved IR risk stratification compared with BMI Z-score alone, opening new perspectives in the prediction of cardiometabolic risk in prepubertal children.
Environmental changes in the northern Antarctic Peninsula provide a sensitive local indicator of climate warming. A consequence of these changes is the activation of surface and subsurface hydrological cycles in areas where water, in colder conditions, would remain frozen. This paper analyses the effects of hydrological cycle activation at Cape Lamb, Vega Island. The conclusions are based on hydrochemistry and isotope interpretation of 51 representative water samples from precipitation, streams, lakes, ice, snow and groundwater. Based on these results relationships between the different components of the hydrological cycle are proposed. This paper highlights the important contribution of groundwater to surface water chemistry, the disconnection of the lakes from the overall flow, the lack of an ocean spray signature in surface water and groundwater and the significant influence of windblown dust in the composition of the analysed waters.
Neurodevelopmental alterations have been described inconsistently in psychosis probably because of lack of standardization among studies. The aim of this study was to conduct the first longitudinal and population-based magnetic resonance imaging (MRI) evaluation of the presence and size of the cavum septum pellucidum (CSP) and adhesio interthalamica (AI) in a large sample of patients with first-episode psychosis (FEP).
FEP patients (n=122) were subdivided into schizophrenia (n=62), mood disorders (n=46) and other psychosis (n=14) groups and compared to 94 healthy next-door neighbour controls. After 13 months, 80 FEP patients and 52 controls underwent a second MRI examination.
We found significant reductions in the AI length in schizophrenia FEP in comparison with the mood disorders and control subgroups (longer length) at the baseline assessment, and no differences in any measure of the CSP. By contrast, there was a diagnosis×time interaction for the CSP length, with a more prominent increase for this measure in the psychosis group. There was an involution of the AI length over time for all groups but no diagnosis×time interaction.
Our findings suggest that the CSP per se may not be linked to the neurobiology of emerging psychotic disorders, although it might be related to the progression of the disease. However, the fact that the AI length was shown to be shorter at the onset of the disorder supports the neurodevelopmental model of schizophrenia and indicates that an alteration in this grey matter junction may be a risk factor for developing psychosis.
Distributions of deep-sea fish, benthic invertebrates and the effects of deep-sea bottom trawling were studied based on data collected in 2005 from a joint collaboration survey undertaken between the Spanish Institute of Oceanography and a deep-sea trawler on the Hatton Bank (north-east Atlantic). A total of 163 valid bottom trawl hauls (600–1600 m) were analysed. The main trawlable grounds were located on the sedimentary seabed of the western flank of the bank (Hatton Drift). Grenadiers and smoothheads were predominant in the trawl catches (67% and 11.8% by weight respectively). Both species were abundant along the western flank. Deep-water sharks accounted for 7.4% of weight, and were abundant along the south-eastern slopes. Chimerids, lotids, morids and other deep-sea species were also taken as by-catch. Grenadiers and deep-water sharks dominated the discards. By-catches of cold-water corals were generally associated with the rocky outcrop and were more abundant at the top of the bank. Abundant by-catches of large sponges, characteristic of sponge-dominated biotopes, were taken from the eastern flank.
The Urban Areas Working Group is part of the International Atomic Energy Agency’s EMRAS II (Environmental Modelling for Radiation Safety) Programme. The goal of this Working Group is to test and improve the capabilities of models used in assessment of radioactive contamination in urban settings, including dispersion and deposition events, short- and long-term contaminant redistribution following deposition events, and potential countermeasures or remediation efforts for reducing human exposures and doses. The Working Group has developed three modeling exercises, which are designed to permit intercomparison of model predictions and, in one case, comparison of model predictions with measurements. This paper describes the scenarios and provides comparisons of initial modeling results. Reasons for similarities and discrepancies among model predictions are discussed in terms of the modeling approaches, models, and parameter values used by different assessors. Preliminary conclusions emphasize the value of explaining individual approaches and the importance of understanding the effects of different assumptions and parameter values on the modeling results.
Both background rotation and small depths are said to enforce the two-dimensionality of flows. In the current paper, we describe a systematic study of the two-dimensionality of a shallow monopolar vortex subjected to background rotation. Using a perturbation analysis of the Navier–Stokes equations for small aspect ratio (with the fluid depth and a typical radial length scale of the vortex), we found nine different regimes in the parameter space where the flow is governed to lowest order by different sets of equations. From the properties of these sets of equations, it was determined that the flow can be considered as quasi-two-dimensional in only five of the nine regimes. The scaling of the velocity components as given by these sets of equations was compared with results from numerical simulations to find the actual boundaries of the different regimes in the parameter space (), where is the Ekman boundary layer thickness and is the equivalent boundary layer thickness for a monopolar vortex without background rotation. Even though background rotation and small depths do promote the two-dimensionality of flows independently, the combination of these two characteristics does not necessarily have that same effect.