Sufficient Scale Research Articles

Patterns of HIV prevalence among injecting drug users in the cross-border area of Lang Son Province, Vietnam, and Ning Ming County, Guangxi Province, China

BackgroundTo assess patterns of injecting drug use and HIV prevalence among injecting drug users (IDUs) in an international border area along a major heroin trans-shipment route.MethodsCross-sectional surveys of IDUs in 5 sites in Lang Son Province, Vietnam (n = 348) and 3 sites in Ning Ming County, Guangxi Province, China (n = 308). Respondents were recruited through peer referral ("snowball") methods in both countries, and also from officially recorded lists of IDUs in Vietnam. A risk behavior questionnaire was administered and HIV counseling and testing conducted.ResultsParticipants in both countries were largely male, in their 20s, and unmarried. A majority of subjects in both countries were members of ethnic minority groups. There were strong geographic gradients for length of drug injecting and for HIV seroprevalence. Both mean years injecting and HIV seroprevalence declined from the Vietnamese site farthest from the border to the Chinese site farthest from the border. 10.6% of participants in China and 24.5% of participants in Vietnam reported crossing the international border in the 6 months prior to interview. Crossing the border by IDUs was associated with (1) distance from the border, (2) being a member of an ethnic minority group, and (3) being HIV seropositive among Chinese participants.ConclusionReducing the international spread of HIV among IDUs will require programs at the global, regional, national, and "local cross border" levels. At the local cross border level, the programs should be coordinated on both sides of the border and on a sufficient scale that IDUs will be able to readily obtain clean injection equipment on the other side of the border as well as in their country of residence.

Social transition and substance abuse

Social transition and substance abuse

Nucleotide Deoxysugars: Essential Tools for the Glycosylation Engineering of Novel Bioactive Compounds

The irreversible spread of new resistance mechanisms against existing therapeutical antibiotics has led to the development of technologies and strategies for the glycosylation engineering of novel antibiotics. Amino-, C-branched and O-methylated 6-deoxyhexoses play a favourite role in the biosynthesis of clinically important antibiotics like tylosin, erythromycin or oleandomycin and are essential for the antibiotic activity. They are transferred onto the aglycon by glycosyltransferases using dTDP-activated deoxyhexoses. The in vitro biochemical characterization of the biosynthetic enzymes and the glycosyltransferases are, however, hampered due to the poor synthetic access to dTDP-activated deoxysugars and their biosynthetic intermediates. The overcoming of the poor availability of dTDP-activated sugars was the target of several researchers to fulfil their distinct aims with these sugars which were mostly involved in the synthesis of different biological active compounds. Several completely different strategies were used in the past years to improve the availability of dTDP-activated deoxysugars, varying from complete enzymatic synthesis via syntheses using reaction technology for yield optimization to full organic synthesis or shortcuts like the decomposition of commercially available antibiotics and later chemical activation of the sugar moieties. This review gives a survey of the synthesis of dTDP-activated sugars by chemical and chemoenzymatic approaches and discusses the promiscuity of glycosyltransferases to evaluate the chances for applying them for the production of new bioactive compounds. It summarizes the most important enzymes in the field of synthesis using biosynthetic pathway enzymes and describes solutions for occurring challenges during application. Finally, this review will give a survey about the availability of dTDP-activated sugars in sufficient scale and will also point at important sugars which are still bottlenecks and difficult to synthesize and therefore should become a target for enhanced research efforts.

Oxygen Sensors Based on Mesoporous Silica Particles on Layer-by-Layer Self-assembled Films

We describe photoluminescent (PL) oxygen sensors based upon phosphorescent dyes adsorbed into the pores of mesoporous silica particles at submonolayer coverage on a layer-by-layer self-assembled film. Eight transition metal dyes (four Pt and Pd porphyrin complexes and four ruthenium complexes) were investigated through monitoring the changes in PL intensity and lifetime upon varying oxygen pressure. The intensity Stern−Volmer (SV) plots were curved. In most systems, the intensity SV plots match the lifetime SV plots, with deviations seen only at high oxygen pressures where static quenching may play a role. The curved intensity Stern−Volmer plots could be fitted with two phenomenological models, a two-site model, and a model based on a Freundlich binding isotherm for oxygen. The Gaussian distribution model was less successful in fitting the data. The most important result to emerge from these data is that the unquenched lifetime of the dye itself is not a sufficient scaling parameter to reduce all of the SV plots to a common line. A second scaling parameter was necessary. This parameter, which measures the capture radius for quenching (Reff), times the efficiency of quenching per encounter α ranged from 0.38 nm for PdOEP and 0.42 for PtTPP to 1.12 for Ru(bpy)3]Cl2 and 1.25 for Ru(phen)3]Cl2 relative to an assumed value of αReff = 1.0 nm for PtOEP.

From Homogeneous Dispersion to MicellesA Molecular Dynamics Simulation on the Compromise of the Hydrophilic and Hydrophobic Effects of Sodium Dodecyl Sulfate in Aqueous Solution

The structural and functional diversity of surfactant systems has attracted simulation works in atomistic, coarse grain, and mesoscopic models (Bandyopadhyay, S.; et al. Langmuir 2000, 16, 942; Senapati, S.; et al. J. Phys. Chem. B 2003, 107, 12906; Maiti, P. K.; et al. Langmuir 2002, 18, 1908; Srinivas, G.; et al. J. Phys. Chem. B 2004, 108, 8153; Groot, R. D.; et al. J. Chem. Phys. 1999, 110, 9739; Rekvig, L.; et al. Langmuir 2003, 19, 8195). However, atomistic models have suffered from their tremendous computational cost and are, so far, not able to simulate the structural behaviors in sufficient spatio-temporal scales (Shelley, J. C.; Shelley, M. Y. Curr. Opin. Colloid Interface Sci. 2000, 5, 101). The other two approaches are not microscopic enough to describe the configurations of the surfactants that determine their behaviors (Shelley and Shelley). In this study, we propose to simplify atomistic models based on the observation that the compromise of the hydrophilic and hydrophobic effects (Li, J.; Kwauk, M. Chem. Eng. Sci. 2003, 58, 521-535) and molecular structures of surfactants are the dominant factors shaping their structures in the systems. With this simplification, we are able to simulate with moderate computing cost the whole process of micelle formation from an initially uniform dispersion of sodium dodecyl sulfate (SDS) in aqueous solution. The resulting micelle structures are different from those predicted by atomistic simulations that started with a predefined micelle configuration at the same surfactant concentrations. However, if we use their initial micelle configuration, micelle structures the same as theirs are obtained. Analyses show that our results are more realistic and that the results of the atomistic simulations suffer from artificial initial conditions. Therefore, our model may serve as a reasonable simplification of atomistic models in terms of the general structure of micelles.

The impact of life skills education on adolescent sexual risk behaviors in KwaZulu-Natal, South Africa

Purpose To assess the impact of exposure to life skills education by youth in KwaZulu-Natal Province (KZN, South Africa) on knowledge and behaviors associated with the spread of HIV/AIDS. Methods Data come from a panel study of 2222 youth from several population subgroups in KZN. The youth were aged 14–24 years when interviewed in 1999 and 2001. The intervention was a full coverage life skills education program for all students in middle and secondary schools. Impact was measured as net dose-response relationships between life skills exposure and outcomes. Econometric methods were used to control for nonrandom exposure to life skills education. Outcomes included sexual behavior and condom use indicators. Results Significant effects, albeit modest in magnitude, were observed on selected areas of sexual-reproductive health knowledge and perceived condom self-efficacy, along with larger effects on condom use at first and last sex. No consistent effects on age at sexual initiation, secondary abstinence, or partnering behaviors were observed among these youth. Conclusions School-based life skills education appears capable of communicating key information and helping youth develop skills relevant to reducing HIV risk. However, the South African national program has yet to be fully implemented, and whether this initiative will result in sustained behavior modification among youth on a sufficient scale to affect the HIV/AIDS epidemic is uncertain.

A Digital Halftoning Using Magic Square

Digital halftoning is essential to print or display a continuous tone with binary devices. Error Diffusion (ED) has been a major stream to produce a pictorial image on inkjet prints, but is not always acceptable for commercial printing or EP printer, because it generates the dispersed dots hard to print.This paper proposes a novel method for generating ordered dither mask using “magic square”. Magic square provides spatially balanced threshold values in row, column, and diagonal directions by the rule of “even-sum”. The proposed magic square satisfies the energy minimum criterion in the local area and is expandable to a large scale for sufficient gray scales. We selected the magic square candidates with Fourier spectra concentrated in the middle spatial frequency to produce a smoothed gradation suitable for LBP or commercial printing. The paper introduces a systematic method for expanding small mask to large mask by “master-slave” algorithm. The experimental results show the improved grayscale reproduction with reduced artifacts in comparison with the conventional Bayer dither or ED.

Natural variation in the sexually selected feather ornaments of crested auklets (Aethia cristatella) does not predict future survival

We evaluated whether sexually selected crest and auricular plume feather ornaments of crested auklet (Aethia cristatella) adults covaried with individual local survival over 11 years (1991--2001). Crested auklets (n e 364 total) were captured near breeding sites, marked with color rings, and local survival estimates were based on color ring resightings at a breeding colony. Survival estimates and relationships among local survival and crest length, auricular plume length, mass and tarsus were evaluated using the program MARK. The best models included four groups, defined by sex and ease of resighting, that differed in resighting rate (p) but not local survival rate (Φ). This model structure effectively explained sources of variation in local survival and resightability among individuals. The best fitting model showed local survival rate varying annually, while accounting for differences in resightability of marked individuals between the sexes and groups (Φ[t], p[sex*ease of resighting]). Annual local survival varied from 0.940 ± 0.029 (SE) in 1993--1994 to 0.767 ± 0.034 in 1997--1998 and averaged 0.859 ± 0.019. We found no evidence that crested auklet local survival covaried with continuous variation in individuals' ornaments. Simulations indicated that our data set was sufficient to detect a relationship between local survival and a covariate that equaled or exceeded a range of 8%. The implications for competing sexual selection mechanisms of empirically measured survival--ornament relationships are controversial, but our study emphasizes that survival estimates for such investigations must control for confounding factors such as resighting rate as well as have sufficient statistical power and time scale to be biologically meaningful. Our results are most consistent with the idea that the conspicuous variation in crested auklet's showy ornaments is arbitrary with respect to individual viability as quantified by their long-term survival. Copyright 2004.

Using the Fisherian concept of income to guide a nation's macro-investment policy

A relatively new group of economists called 'ecological economists' believe that continuing macro-economic expansion eventually leads to a decline in sustainable economic welfare. Ecological economists have therefore called for a halt to the high-growth policies being widely adopted by many governments. To support their belief, and to demonstrate how Fisherian income can serve as a useful guide to a nation's macro-investment policy, a relatively simple formula for calculating Fisherian income is introduced and calculated for Australia for the period 1967-1997. The empirical evidence suggests that Australia may have surpassed its optimal or sufficient macro-economic scale in the mid-1970s. While, around this time, Australia began a transition to a lower rate of growth that arrested the steep decline in per capita Fisherian income, Australia had reverted back to a high-growth policy by the end of the study period. It chose not to continue the deceleration towards a steady-state economy. By 1997, per capita Fisherian income had increased to mid-1970s levels; however, the recent change in Australia's macro-investment policy is likely to have a detrimental long-term impact on the sustainable economic welfare enjoyed by its citizens.

Practical measures that improve human rights – towards health equity for Aboriginal children

If Australian public health policy is driven by the need for health equity, then program gaps and the unaddressed health needs of Aboriginal children should be providing unambiguous direction for health sector investments. This, however, is not the case. This paper details the urgent effort required to meet the needs of Aboriginal children and refers to lessons from within Australia and international studies. It provides examples where health policy and programs can be improved in the areas of child nutrition, hearing loss, immunisation coverage, and preventive health assessments. Recommendations include the need for the adoption of a policy framework for maternal and child health, concomitant national performance indicators, nutritional supplementation programs in order to ensure that no Aboriginal child shall suffer from malnutrition in rural and remote Australia, multifaceted measures to enhance the immunisation coverage of Aboriginal children and preventive child health assessments. Underpinning these measures is a need to augment the capacity of Aboriginal Community Controlled Health Services across Australia as these services play a predominant role in delivering preventive health care, community development and support services to the Aboriginal population. Stated commitments to social justice principles have not translated into 'practical measures' in Australia for Aboriginal children. There must be unequivocal commitment of a sufficient scale for practical measures to reduce health inequalities.

Why ADCo? Why Now? An Economic Exploration into the Future of Industry Structure for the "Last Mile" in Local Telecommunications Markets

This Policy Paper discusses important economic characteristics of local exchange markets and the firms that participate therein. First, this Policy Paper, building on the work in PHOENIX CENTER POLICY PAPER NO. 10, explains that entry into the local exchange market requires large fixed and sunk costs, making entry risky and necessitating scale economies. Consequently, only a few local access networks can supply the market. These few local access networks cannot be small, however, because a large market share is required to realize sufficient scale economies to effectively compete with the Incumbent Local Exchange Carrier or and survive. Secondly, using publicly available data from the Federal Communications Commission and industry filings with the Security and Exchange Commission, this Policy Paper explains that acquiring sufficient market share in network services to realize scale economies may be difficult for entrants who either attempt to purchase unbundled network elements from the incumbent or attempt to build their own network from the ground up. Instead, given the substantial scale economies required in the local exchange network, it may not be possible for a single carrier to acquire sufficient retail market share in a timely manner to exhaust economies of scale in its wholesale network. An integrated firm supplying the wholesale market, in an effort to expand output, is conflicted; the integrated firm's retail market share raises the opportunity cost of wholesale supply. Accordingly, this Policy Paper shows that if economies of scale are sufficiently large, reaching a scale of operation that allows the entrant to compete with the ILEC may be best achieved through the entry of an Alternative Distribution Company or which is a wholesale-only carriers'-carrier for the proverbial last mile. (This is a very different concept from a LoopCo, which is formed via the structural separation of the ILEC's network facilities and marketing operations.) The ADCo can consolidate the consumer demand held by retail CLECs, thereby reducing risk and costs by expanding output quickly. The disincentives to wholesale supply possessed by the integrated firm, furthermore, do not exist for the ADCo, and therefore the ADCo - unlike the ILEC - has no incentive to sabotage its customers (i.e., the ability to increase or raise the cost of a rival's key input of production by non-price behavior.) As a result, while the number of local access networks the market can sustain may be few, the exclusively wholesale nature of the ADCo nonetheless permits the number of providers of advanced telecoms products and services to be many (the raison d'etre of market restructuring). Equally as important, given the existence of these discriminatory incentives resulting from the current and foreseeable economic conditions of the U.S. telecommunications industry, the most probable and viable long term, competitive market structure involves a substantial presence by an unintegrated, but larger wholesale supplier - in other words, an ADCo - to function efficiently. As such, their presence in the market should be welcomed and encouraged.

A New Approach to Rapid Parallel Development of Four Neurokinin Antagonists. Part 4. Synthesis of ZD2249 Methoxy Sulfoxide

The manufacture of ZD2249 methoxy sulfoxide (1) using a new project approach is described. Research department processes were scaled up to 100 L if process safety and robustness were not compromised; other factors were treated according to the new approach. Using this strategy, we were able to manufacture a key intermediate on sufficient scale to support delivery of 1 kg quantities of bulk drug within 6 months of the start of lab work.

The Performance of Internet-based Business Models: Evidence from the Banking Industry

The initial Internet bank startups tended to underperform branching bank startups. This suggested that Internet‐only business models were not economically viable for banks. However, firms that pioneer new business models may benefit substantially from experience as they grow older, and firms that use automated production technologies may benefit from scale effects as they grow larger. Econometric analysis of Internet‐only bank startups finds strong evidence of the latter, but not the former, effect. The results suggest that Internet‐only banking success depends on attaining sufficient scale and strong management practices.

A New Approach to Rapid Parallel Development of Four Neurokinin Antagonists. Part 2. Synthesis of ZD6021 Cyano Acid

The manufacture of ZD6021 cyano acid (1) using a new project approach is described. Research Department processes were scaled up to 100 L if process safety and robustness were not compromised; other factors were treated according to the new approach. By using this strategy, we were able to manufacture a key intermediate on sufficient scale to support delivery of 1 kg quantities of bulk drug within 6 months of the start of lab work.

Quantifying the sequence stratigraphy and drowning mechanisms of atolls using a new 3‐D forward stratigraphic modelling program (CARBONATE 3D)

ABSTRACTThis paper describes a new 3‐D forward numerical model (CARBONATE 3D) that simulates the stratigraphic and sedimentological development of carbonate platforms and mixed carbonate–siliciclastic shelves by simulating the following sedimentary processes: (1) Carbonate shallow, open‐marine production, dependent on water depth, restriction and sediment input; (2) Carbonate shallow, restricted‐marine production, dependent on water restriction; (3) Pelagic sediment production and deposition; (4) Coarse and fine siliciclastic input; (5) Erosion, transport and redeposition of sediment, dependent on currents, slope, depth and restriction as well as sediment grain‐size and composition; (6) Dissolution of subaerially exposed carbonate. In this paper the model is used to investigate the controlling mechanisms on the sequence stratigraphy of isolated carbonate platforms and atolls and to predict distinctive architectural signatures from different drowning mechanisms. Investigation of the mechanisms controlling atoll strata shows that although relative sea‐level is the major control, antecedent topography, environmental setting and early diagenesis have profound influence on what stratigraphic geometries and facies develop. Hence care must be taken if sea‐level curves are interpreted from real stratigraphies. Atoll drowning by fast sea‐level rise, by lowered production and by repeated exposure and fast subsequent sea‐level rises are investigated and different stratigraphic signatures for the respective mechanisms predicted. A fast relative sea‐level rise results in a bucket‐shaped morphology developed prior to drowning and a sharp transition from the platform margin facies to a pelagic cover. Drowning caused by lowered platform margin production is predicted to result in the development of a dome‐shaped, shallow‐water shoal over the whole platform top prior to drowning. Fourth order amplitudes of several tens of metres, typical of ‘icehouse’ settings, cause atoll drowning at subsidence rates where atolls subject to fourth order amplitude of only a few metres, typical of ‘greenhouse’ settings, can keep up with the rising sea‐level. In the resultant strata, vertical facies belts are less well developed but horizontally extensive facies bands are more prominent. High fourth order amplitudes (up to 80 m) without sufficient third order scale subsidence will not lead to drowning, however, as the platform can recover in each fourth order lowstand. These results suggest that atolls might be easier to drown in ‘icehouse’ rather than in ‘greenhouse’ conditions but only in situations with suitably high rates of longer‐term relative sea‐level rise or sufficient lag times.

Forecasting the diffusion of photovoltaic systems in southern Europe: A learning curve approach

Most analysts disagree upon whether photovoltaic systems (PV) will be able to play an important role in the energy scenarios of the future. A few scholars also question the appropriateness of policies that envisage the use of public subsidies to stimulate the growth of this industry and to accelerate market penetration. This paper contributes to this debate by examining whether carefully designed policies may initiate a process of large-scale diffusion of grid-connected PV, even without the deployment of external subsidies. Building upon a disaggregated characterization of the electricity market, it takes endogenously into account the learning curve phenomenon and simulates the diffusion of PV building-integrated systems in five European countries. The analysis is restricted to crystalline silicon systems and is repeated under four different macroeconomic scenarios corresponding to four different energy policies. The results suggest that already today there are opportunities for PV diffusion in many islands of the Mediterranean region, which may trigger sufficient scale economies to render the technology competitive in larger markets. They also show that the diffusion process could be accelerated through the implementation of carbon-tax policies that support initial penetration. The environmental benefits (net avoided CO 2 emissions over the system life cycle) associated with the forecasted penetration are also evaluated.

Roland-Morris Scale Reliability

Letter to the Editor: There is much more research that describes the measurement properties of evaluative measures such as the Roland-Morris (RM) scale1 today than there was a decade ago. The greater volume of studies provides more data that can be used to shape clinical decisions. This increased amount of research also increases the chance that the results of some studies, at times, may conflict with results of other studies. As the number of studies on a particular issue grows, the potential for conflicting results increases. The study of Davidson and Keating2 seems to be an illustration of this phenomenon. Davidson and Keating2 examined the reliability and responsiveness of 5 functional status questionnaires designed for patients with low back pain (LBP). One of the scales examined was the RM scale, a questionnaire that has been studied extensively by our group and many others. Davidson and Keating found that the reliability of RM scale measurements was low, with an intraclass correlation coefficient (ICC [2,1]) of .53 (95% confidence interval [CI]=.29,.71) for a sample of 47 patients with LBP who reported that their LBP was “about the same,” “a little better,” or “a little worse.” For a smaller subgroup that reported their LBP was “about the same,” the ICC (2,1) was lower at .42 (95% CI=−;.07, .75). Based in part on these findings, the authors concluded that the RM scale “appeared to lack sufficient reliability and scale width for clinical application.”2(p8) In our opinion, these results are dramatically different from the large volume of evidence reported in the literature on the reliability of RM scale scores (Table).1,2,6–17 The evidence summarized in the Table was collected on diverse samples of patients from different countries with many different LBP diagnoses. Davidson and …

Europe ramps up its research goals

Europe ramps up its research goals

Breeding Perennial Grain Crops

Referee: Ms. Peggy Wagoner, Rodale Institute, 611 Siegfriedale Road, Kutztown, PA 19530-9749One-third of the planet's arable land has been lost to soil erosion in recent decades, and the pace of this degradation will increase as the limits of our food production capacity are stretched. The persistent problem of worldwide soil erosion has rekindled interest in perennial grain crops. All of our current grain crops are annuals; therefore, developing an array of new perennial grains - grasses, legumes, and others – will require a long-term commitment. Fortunately, many perennial species can be hybridized with related annual crops, allowing us to incorporate genes of domestication much more quickly than did our ancestors who first selected the genes. Some grain crops — including rye, rice, and sorghum — can be hybridized with close perennial relatives to establish new gene pools. Others, such as wheat, oat, maize, soybean, and sunflower, must be hybridized with more distantly related perennial species and genera. Finally, some perennial species with relatively high grain yields — intermediate wheatgrass, wildrye, lymegrass, eastern gamagrass, Indian ricegrass, Illinois bundleflower, Maximilian sunflower, and probably others — are candidates for direct domestication without interspecific hybridization. To ensure diversity in the field and foster further genetic improvement, breeders will need to develop deep gene pools for each crop. Discussions of breeding strategies for perennial grains have concentrated on allocation of photosyn-thetic resources between seeds and vegetative structures. However, perennials will likely be grown in more diverse agro-ecosystems and require arrays of traits very different from those usually addressed by breeders of annuals. The only way to address concerns about the feasibility of perennial grains is to carry out breeding programs with adequate resources on a sufficient time scale. A massive program for breeding perennial grains could be funded by diversion of a relatively small fraction of the world's agricultural research budget.

A comparison of refuse attenuation in laboratory and field scale lysimeters

For this study, small and middle scale laboratory lysimeters, and a large scale field lysimeter in situ in Shanghai Refuse Landfill, with refuse weights of 187, 600 and 10,800,000 kg, respectively, were created. These lysimeters are compared in terms of leachate quality (pH, concentrations of COD, BOD and NH 3–N), refuse composition (biodegradable matter and volatile solid) and surface settlement for a monitoring period of 0–300 days. The objectives of this study were to explore both the similarities and disparities between laboratory and field scale lysimeters, and to compare degradation behaviors of refuse at the intensive reaction phase in the different scale lysimeters. Quantitative relationships of leachate quality and refuse composition with placement time show that degradation behaviors of refuse seem to depend heavily on the scales of the lysimeters and the parameters of concern, especially in the starting period of 0–6 months. However, some similarities exist between laboratory and field lysimeters after 4–6 months of placement because COD and BOD concentrations in leachate in the field lysimeter decrease regularly in a parallel pattern with those in the laboratory lysimeters. NH 3–N, volatile solid (VS) and biodegradable matter (BDM) also gradually decrease in parallel in this intensive reaction phase for all scale lysimeters as refuse ages. Though the concrete data are different among the different scale lysimeters, it may be considered that laboratory lysimeters with sufficient scale are basically applicable for a rough simulation of a real landfill, especially for illustrating the degradation pattern and mechanism. Settlement of refuse surface is roughly proportional to the initial refuse height.