Sufficient Scale Research Articles

HIV infection among people who inject drugs: the challenge of racial/ethnic disparities.

Racial/ethnic disparities in HIV infection, with minority groups typically having higher rates of infection, are a formidable public health challenge. In the United States, among both men and women who inject drugs, HIV infection rates are elevated among Hispanics and non-Hispanic Blacks. A meta-analysis of international research concluded that among persons who inject drugs, racial and ethnic minorities were twice as likely to acquire an HIV infection, though there was great variation across the individual studies. To examine strategies to reduce racial/ethnic disparities among persons who inject drugs, we reviewed studies on injection drug use and its role in HIV transmission. We identified four sets of evidence-based interventions that may reduce racial/ethnic disparities among persons who inject drugs: HIV counseling and testing, risk reduction services, access to antiretroviral therapy, and drug abuse treatment. Implementation of these services, however, is insufficient in many countries, including the United States. Persons who inject drugs appear to be changing drug use norms and rituals to reduce their risks. The challenges are to (a) develop a validated model of how racial/ethnic disparities in HIV infection arise, persist, and are reduced or eliminated over time and (b) implement evidence-based services on a sufficient scale to eliminate HIV transmission among all persons who inject drugs.

Controls on magmatic cycles and development of rift topography of the Manda Hararo segment (Afar, Ethiopia): Insights from cosmogenic 3He investigation of landscape evolution

Crustal extension at mature continental rifts and oceanic ridges occurs by a combination of normal faulting and magma injection, which interact to create rift morphology. Quantifying the relative roles of faulting and melt intrusion in accommodating extension at magmatic rifts remains difficult and requires studies at sufficient spatial and temporal scales to resolve the interaction between these processes. In this study we provide new chronological constraints based on cosmogenic exposure dating for the ∼100kyr topographic evolution of a young and active magmatic rift segment in Afar, Ethiopia. We combine structural investigations, field mapping, geochemical analysis and cosmogenic 3He exposure dating of lava surfaces in order to investigate the interplay between volcanic activity and fault growth in the northern part of the axial depression, where the rift segment intersects a large stratovolcano. Our results allow us to determine the roles of the various magma reservoirs feeding this rift system and their interactions during accretion over the past 100kyr. New age data for key lava units allow several magmatic cycles to be distinguished. Each cycle lasts 20–40ka resulting in periods of high and low magma supply rate. The variations in magma supply rate at the segment extremity strongly affect the development of the rift depression, with the availability of melt controlling the morphological impact of faulting. Melts from different magma reservoirs feeding the segment are chemically distinct and geochemical analysis of lavas from the rift floor allows their respective contributions to maintaining magmatic accretion to be estimated. We propose that melts from the magma reservoir at the northern end of the segment contribute around one-third of the length of this portion of the segment, whereas the mid-segment reservoir is responsible for the remaining two-thirds of the segment accretion.

A low carbon economy and society

This paper examines various aspects of moving from high carbon economies and societies to a cluster of low carbon systems. First, some historical material is considered from the Second World War and the 1970s, periods with some lessons for the contemporary 'powering down' of whole societies. Second, analysis is provided of some green shoots of a powering down of existing systems identifiable in the contemporary developed world. Third, analysis is provided of the array of systems, social practices and innovations that would have to develop in order to effect powering down on a sufficient scale and within an appropriate time period. Most examples are drawn from transport and mobility. Finally, the paper demonstrates just why developing new systems is so hard, especially as this must involve a transformed cluster of systems. The forces that make a new cluster unlikely are exceptionally powerful and make this a very difficult but not impossible outcome.

Scale effects on propeller cavitating hydrodynamic and hydroacoustic performances with non-uniform inflow

Considering the lack of theoretical models and ingredients necessary to explain the scaling of the results of propeller cavitation inception and cavitating hydroacoustics from model tests to full scale currently, and the insufficient reflection of the nuclei effects on cavitation in the numerical methods, the cavitating hydrodynamics and cavitation low frequency noise spectrum of three geometrically similar 7-bladed highly skewed propellers with non-uniform inflow are addressed. In this process, a numerical bridge from the multiphase viscous simulation of propeller cavitation hydrodynamics to its hydro-acoustics is built, and the scale effects on performances and the applicability of exist scaling law are analyzed. The effects of non-condensable gas(NCG) on cavitation inception are involved explicitly in the improved Sauer’s cavitation model, and the cavity volume acceleration related to its characteristic length is used to produce the noise spectrum. Results show that, with the same cavitation number, the cavity extension on propeller blades increases with diameter associated with an earlier shift of the beginning point of thrust decline induced by cavitation, while the three decline slopes of thrust breakdown curves are found to be nearly the same. The power of the scaling law based on local Reynolds number around 0.9R section is determined as 0.11. As for the smallest propeller, the predominant tonal noise is located at blade passing frequency(BPF), whereas 2BPF for the middle and both 2BPF and 3BPF for the largest, which shows the cavitating line spectrum is fully related to the interaction between non-uniform inflow and fluctuated cavity volume. The predicted spectrum level exceedance from the middle to the large propeller is 6.65 dB at BPF and 5.94 dB at 2BPF. Since it just differs less than 2 dB to the increment obtained by empirical scaling law, it is inferred that the scale effects on them are acceptable with a sufficient model scale, and so do the scaling law. The numerical implementation of cavitating hydrodynamics and hydro-acoustics prediction of propeller in big scale in wake has been completed.

Directed quantum communication

We address the question of whether there is a way of characterizing the quantum information transport properties of a medium or material. For this analysis, the special features of quantum information have to be taken into account. We find that quantum communication over an isotropic medium, as opposed to classical information transfer, requires the transmitter to direct the signal toward the receiver. Furthermore, for large classes of media there is a threshold, in the sense that ‘sufficiently much’ of the signal has to be collected. Therefore, the medium's capacity for quantum communication can be characterized in terms of how the sizes of the transmitter and receiver have to scale with the transmission distance to maintain quantum information transmission. To demonstrate the applicability of this concept, an n-dimensional spin lattice is considered, yielding a sufficient scaling of δn/3 with the distance δ.

MENTOR ÖĞRETMENLERİN YAPILANDIRMACI ÖĞRE

The present study tried to evaluate prospective teachers’ perceptions of mentor teachers’ sufficiency level on the use of constructivist learning approach. Study group consisted of fourth year students enrolled at Firat, Adiyaman, Inonu, Kilis 7 Aralik, Gaziantep, Dicle, Erzincan, Cumhuriyet, Ibrahim Cecen, Kafkas, Alpaslan, Hatay, Siirt, Ataturk and Van 100. Yil Universities in the spring term of 2009-2010 academic year. Both quantitative and qualitative data collection methods were used for the study. For the quantitative part of the study, “Teachers’ Sufficiency Scale in Relation to Constructivist Learning”, developed by Karadag (2007), was used as the data collection tool. An interview form including four semi-structured questions was used for the qualitative part of the study. Validity and reliability of the data collection tools were calculated (Alpha: 0.79, Spearman-Brown: 0.77, Gutmann Split-Half: 0.75) and the results proved that they were both valid and reliable. Mean score, standard deviation, Independent samples t test, one way ANOVA, Mann Whitney U and LSD tests and content analyses were used to analyze quantitative and qualitative data. Results with p

Priority interventions to reduce HIV transmission in sex work settings in sub‐Saharan Africa and delivery of these services

IntroductionVirtually no African country provides HIV prevention services in sex work settings with an adequate scale and intensity. Uncertainty remains about the optimal set of interventions and mode of delivery.MethodsWe systematically reviewed studies reporting interventions for reducing HIV transmission among female sex workers in sub-Saharan Africa between January 2000 and July 2011. Medline (PubMed) and non-indexed journals were searched for studies with quantitative study outcomes.ResultsWe located 26 studies, including seven randomized trials. Evidence supports implementation of the following interventions to reduce unprotected sex among female sex workers: peer-mediated condom promotion, risk-reduction counselling and skills-building for safer sex. One study found that interventions to counter hazardous alcohol-use lowered unprotected sex. Data also show effectiveness of screening for sexually transmitted infections (STIs) and syndromic STI treatment, but experience with periodic presumptive treatment is limited. HIV testing and counselling is essential for facilitating sex workers’ access to care and antiretroviral treatment (ART), but testing models for sex workers and indeed for ART access are little studied, as are structural interventions, which create conditions conducive for risk reduction. With the exception of Senegal, persistent criminalization of sex work across Africa reduces sex workers’ control over working conditions and impedes their access to health services. It also obstructs health-service provision and legal protection.ConclusionsThere is sufficient evidence of effectiveness of targeted interventions with female sex workers in Africa to inform delivery of services for this population. With improved planning and political will, services – including peer interventions, condom promotion and STI screening – would act at multiple levels to reduce HIV exposure and transmission efficiency among sex workers. Initiatives are required to enhance access to HIV testing and ART for sex workers, using current CD4 thresholds, or possibly earlier for prevention. Services implemented at sufficient scale and intensity also serve as a platform for subsequent community mobilization and sex worker empowerment, and alleviate a major source of incident infection sustaining even generalized HIV epidemics. Ultimately, structural and legal changes that align public health and human rights are needed to ensure that sex workers on the continent are adequately protected from HIV.

Human rights abuses and collective resilience among sex workers in four African countries: a qualitative study

BackgroundSex work is a criminal offence, virtually throughout Africa. This criminalisation and the intense stigma attached to the profession shapes interactions between sex workers and their clients, family, fellow community members, and societal structures such as the police and social services.MethodsWe explore the impact of violence and related human rights abuses on the lives of sex workers, and how they have responded to these conditions, as individuals and within small collectives. These analyses are based on data from 55 in-depth interviews and 12 focus group discussions with female, male and transgender sex workers in Kenya, South Africa, Uganda and Zimbabwe. Data were collected by sex worker outreach workers trained to conduct qualitative research among their peers.ResultsIn describing their experiences of unlawful arrests and detention, violence, extortion, vilification and exclusions, participants present a picture of profound exploitation and repeated human rights violations. This situation has had an extreme impact on the physical, mental and social wellbeing of this population. Overall, the article details the multiple effects of sex work criminalisation on the everyday lives of sex workers and on their social interactions and relationships. Underlying their stories, however, are narratives of resilience and resistance. Sex workers in our study draw on their own individual survival strategies and informal forms of support and very occasionally opt to seek recourse through formal channels. They generally recognize the benefits of unified actions in assisting them to counter risks in their environment and mobilise against human rights violations, but note how the fluctuant and stigmatised nature of their profession often undermines collective action.ConclusionsWhile criminal laws urgently need reform, supporting sex work self-organisation and community-building are key interim strategies for safeguarding sex workers’ human rights and improving health outcomes in these communities. If developed at sufficient scale and intensity, sex work organisations could play a critical role in reducing the present harms caused by criminalisation and stigma.

Searching for Solidarity in an Atomized Society

Searching for Solidarity in an Atomized Society

Quantifying Australia's 'Three Speed' Boom

This paper examines Australia’s terms of trade boom since 2003 with a particular interest in quantifying the links between the terms of trade and sectoral performance and identifying an associated ‘secondary services boom’. Comparative static general equilibrium modelling and empirical analysis are used to examine the sectoral impacts on employment and income. The modelling confirms the services expansion of sufficient scale to tighten national labour markets and it projects an associated manufacturing contraction. A separate empirical analysis approaches the same links using vector auto-regressions estimated from pre-boom Australian data (1989 through 2002) and out of sample simulations over the subsequent boom period. The secondary services boom appears clearly but the results on manufacturing are ambiguous. Actual employment booms were larger, and manufacturing sector performance better, than predicted on the estimated VARs, suggesting that the recent boom accompanied changes in industrial structure and underlying behavioural parameters that have been favourable to surviving manufacturing firms.

Potential estimation of hourly blank storage space and charge loads of EVs using road traffic census and vehicles status

AbstractIf both EVs (Electric Vehicles, includes plug‐in hybrid electric vehicles) and renewable energies spread in large quantities, it is possible to control the supply fluctuation of renewable energies using the storage battery of EVs. This research sought to show the charge load potential of EVs based on the state of the Japanese passenger car using traffic census results, etc. Furthermore, it tried to show the trend of the storage battery capacity according to time. From the estimated results: (1) the charge electricity of low and middle distance gets a majority of the total charge demand, (2) charge load changes according to time several times, and the minimum load is the number of gigawatt‐hours at early morning, (3) if night charge is assumed, the standby charge demand of noon will reach tens of gigawatt‐hours, it may have sufficient scale for supply fluctuation control of PVs. Although the present EV is not suitable for long‐distance running, these are expected to be 30 or less percent of the total charge demand. The estimated storage capacity potential in this research will not change numbers of times. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(3): 30–38, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22352

Large eddy simulation of controlled transition to turbulence

Large eddy simulation of H- and K-type transitions in a spatially developing zero-pressure-gradient boundary layer at Ma∞ = 0.2 is investigated using several subgrid scale (SGS) models including constant coefficient Smagorinsky and Vreman models and their dynamic extensions, dynamic mixed scale-similarity, dynamic one-equation kinetic energy model, and global coefficient Vreman models. A key objective of this study is to assess the capability of SGS models to predict the location of transition and the skin friction throughout the transition process. The constant coefficient models fail to detect transition, but the dynamic procedure allows for a negligible turbulent viscosity in the early transition region. As a result, the “point” of transition is estimated correctly. However, after secondary instabilities set in and result in the overshoot in the skin friction profile, all models fail to produce sufficient subgrid scale shear stress required for the correct prediction of skin friction and the mean velocity profile. The same underprediction of skin friction persists into the turbulent region. Spatially filtered direct numerical simulation data in the same boundary layers are used to provide guidelines for SGS model development and validation.

Editorial Commentary: The Endgame for Serogroup A Meningococcal Disease in Africa?

Editorial Commentary: The Endgame for Serogroup A Meningococcal Disease in Africa?

Up, down and around the stack

Broadband characterization has recently attracted much attention from the research community and the general public. Given this interest and the important business and policy implications of residential Internet service characterization, recent years have brought a variety of approaches to profiling Internet services, ranging from Web-based platforms to dedicated infrastructure inside home networks. We have previously argued that network-intensive applications provide an almost ideal vantage point for broadband service characterization at sufficient scale, nearly continuously and from end users. While we have shown that the approach is indeed effective at characterization and can enable performance comparisons between service providers and geographic regions, a key unanswered question is how well the performance characteristics captured by these network-intensive applications can predict the overall user experience with other applications. In this paper, using BitTorrent as an example network-intensive application, we present initial results that demonstrate how to obtain estimates of bandwidth and latency of a network connection by leveraging passive monitoring and limited active measurements from network intensive applications. We then analyze user experienced web performance under a variety of network conditions and show how estimated metrics from this network intensive application can serve as good web performance predictors.

Early Paleozoic mafic magmatic events on the eastern margin of the Siberian Craton

Neoproterozoic and Devonian mafic flows, sills and dykes associated with synchronous rifting events are widely distributed along the long-lived Mesoproterozoic to Mesozoic passive eastern margin of the Siberian Craton. Early Paleozoic magmatic events are also present, but are poorly studied, including Early Cambrian volcanic rocks in the Kharaulakh Range and ca. 450Ma age mafic intrusions of the Suordakh event in the Sette–Daban Range. Both suites of early Paleozoic magmatic rocks are characterized by high Ti concentrations (>3wt.% TiO2), ocean island basalt (OIB)-type trace element and rare earth element (REE) patterns, and high εNd(t) values that generally vary between 6 and 9. The Kharaulakh magmas were formed during low degree partial melting of an enriched region of mantle at depths >90km, generating a suite of alkaline basalts. In comparison, the Suordakh magmas were formed during higher degree partial melting of less enriched mantle at depths <90km, forming alkaline to subalkaline basalts. Both suites are characterized by εNd(t) values suggestive of interaction between enriched and depleted magmas and both were emplaced in within-plate tectonic settings. Although Kharaulakh and Suordakh magmatic rocks have relatively small areal extents, significant parts of them are likely hidden below clastic rocks of the Lower Carboniferous–Jurassic Verkhoyansk Complex. The Kharaulakh magmatic rocks may have counterparts in the Canadian Cordillera, that together could be of sufficient scale to define a Large Igneous Province (LIP). Early Cambrian mafic volcanic rocks in the study area are associated with locally distributed terrigenous units in both the Kharaulakh and Sette–Daban ranges, suggesting that this magmatism was related to a rifting event. Modeling of sedimentary basin subsidence in the Sette–Daban area is also supportive of an Early Cambrian rifting event. However, the intrusive rocks associated with the ca. 450Ma Suordakh mafic magmatic event are not related to any rift-related sediments or structures. Contemporaneous granites may be interpreted as silicic magmatism associated with a LIP event.

Seawater desalination: nanofiltration—a substitute for reverse osmosis?

We present the possibility to replace the first-stage reverse osmosis (RO) seawater by nanofiltration (NF) membranes. Then, we tested few membranes in the laboratory (NF200, NF2540, MPS44, and MPS34) on synthetic and natural seawater, for 2.6 m2 membrane area pilot. We observed that the membrane NF200 is the best membrane from all tested due to its higher productivity with 1.8 L h-1 m-2 bar-1 and its higher salt rejection with 60%. Furthermore, as expected, NF200 filtration of natural seawater permits to decrease SDI3 to a value of 4 ± 2%/min and total organic carbon under 0.1 mg/L, eliminating totally the risk of biofouling development on second-stage RO treatment. The configuration NF200-SW30 gave the best energy gain with 29%. The permeate obtained presents a total dissolved solids of 324 ppm and the flow yield ratio increase of 16%, in reference to SW30-SW30 configuration. Also, we tested the limits of ROSATM simulation, especially for NF membranes. We observed lots of flaws, especially for high pressures and high salts concentrations. As a consequence, each simulation realized for NF must be validated by experiments on real seawater to a sufficient scale and during sufficient time of experiments.

Assessing the impact of mid-to-late Holocene ENSO-driven climate change on toxic Macrozamia seed use: a 5000 year record from eastern Australia

Palaeoenvironmental and palaeoclimatic data indicate that during the mid-to-late Holocene eastern Australia became significantly drier and experienced more intense and more frequent droughts. These changes, driven by the re-emergence and intensification of the ENSO climate phenomena, have been argued to have had considerable impact on Aboriginal societies, although there is uncertainty as to the exact nature, timing and magnitude of this impact. This paper analyses changes in the utilisation of toxic Macrozamia (cycad) seeds at seven archaeological sites in eastern Australia, identifying an extremely close correlation between the intensity of seed use and two proxy ENSO datasets, and a weaker correlation with a third ENSO dataset. Given the ecological attributes and resource potential of these plants, it is argued that these correlations are best explained as an intensified exploitation of a lower-ranked resource in direct response to the increased subsistence risks and lower productivity created by ENSO-driven climatic conditions. It also suggests that by 3000 BP the intensification of the ENSO system was driving changes in human subsistence behaviour on a sufficient scale to have considerable impact on other aspects of the wider cultural systems.

Scale economies, consistent conjectures and teams

This paper models the behavior of team members in a consistent conjectures equilibrium. When subject to scale economies, team members produce more than Nash and when subject to scale diseconomies, they produce less than Nash. Moreover, even when effort levels of team members are perfect substitutes in production, they can be strategic complements in the face of scale economies. Finally, with sufficient scale economies, the complementarity eliminates free-riding and the team optimum is obtained.

Land Reform as a Counterinsurgency Policy

Can targeted land reform reduce levels of civil war conflict by mitigating the factors that contribute to rural rebellion? This article uses new micro-level data on land reform and insurgency at the municipal level from Colombia from 1988 to 2000, a country with high rates of land inequality and informal land ownership, to test whether land reform undercut subsequent guerrilla activity. The reform had two distinct aspects. Politically powerful large landholders blocked most large-scale reform, which resulted primarily in an enduring, low-intensity, and geographically dispersed reform that spurred low levels of insurgent activity. Larger-scale reforms were only implemented in areas that threatened serious violence and had the potential to harm elite interests, and in these limited areas reform reduced guerrilla activity. This suggests that while land reform can be an effective counterinsurgency policy, it may be politically difficult to implement at a sufficient scale because it threatens the status quo.

Green nanophotonics

Nanotechnology, in particular nanophotonics, is proving essential to achieving green outcomes of sustainability and renewable energy at the production scales needed. Nanomaterials enable optimization of optical, opto-electrical, and thermal responses. Optical harmonization of material responses to environmental energy flows involves large changes in spectral response over limited wavelength bands and tailoring to environmental dynamics. The latter includes engineering angle of incidence dependencies and switchable (or chromogenic) responses. Nanomaterials can be made at sufficient scale and low enough cost to be economical and have high impact on a short time scale. Issues to be addressed include human safety and property changes induced during manufacture, handling, and outdoor use. Unexpected advantages have arisen in this work such as the savings and environmental benefits of cool roofs extending beyond the more obvious benefit of reduced heat flows from the roof into the building. We explore some of the likely elements involved in harmonizing nature and technology with applications of nanophotonics to reduce the use of energy in buildings.