Generalizing the Network Scale-Up Method: A New Estimator for the Size of Hidden Populations

The network scale-up method enables researchers to estimate the size of hidden populations, such as drug injectors and sex workers, using sampled social network data. The basic scale-up estimator offers advantages over other size estimation techniques, but it depends on problematic modeling assumptions. We propose a new generalized scale-up estimator that can be used in settings with non-random social mixing and imperfect awareness about membership in the hidden population. Further, the new estimator can be used when data are collected via complex sample designs and from incomplete sampling frames. However, the generalized scale-up estimator also requires data from two samples: one from the frame population and one from the hidden population. In some situations these data from the hidden population can be collected by adding a small number of questions to already planned studies. For other situations, we develop interpretable adjustment factors that can be applied to the basic scale-up estimator. We conclude with practical recommendations for the design and analysis of future studies

The Network Survival Method for Estimating Adult Mortality: Evidence From a Survey Experiment in Rwanda.

Adult death rates are a critical indicator of population health and well-being. Wealthy countries have high-quality vital registration systems, but poor countries lack this infrastructure and must rely on estimates that are often problematic. In this article, we introduce the network survival method, a new approach for estimating adult death rates. We derive the precise conditions under which it produces consistent and unbiased estimates. Further, we develop an analytical framework for sensitivity analysis. To assess the performance of the network survival method in a realistic setting, we conducted a nationally representative survey experiment in Rwanda (n = 4,669). Network survival estimates were similar to estimates from other methods, even though the network survival estimates were made with substantially smaller samples and are based entirely on data from Rwanda, with no need for model life tables or pooling of data from other countries. Our analytic results demonstrate that the network survival method has attractive properties, and our empirical results show that this method can be used in countries where reliable estimates of adult death rates are sorely needed

Evaluation Of Different Probiotic Products For Nursery Pigs

Cassandra JonesA total of 315 nursery pigs (200 × 400; DNA, Columbus, NE; initially 13.6 lb BW) were used in a 44 d study to determine the effects of experimental probiotics on the growth performance of nursery pigs. Pigs were weaned at 21 d of age (d 0 of the experiment) and randomly assigned to 1 of 9 treatments with 5 pigs per pen and 7 pens per treatment based on gender and BW. Dietary treatments consisted of: 1) a control diet without antibiotic or probiotic; 2) the control diet with an antibiotic (Mecadox 10; 50 g/ton of diet); 3) the control diet with a commercial probiotic (Bioplus 2B; 1 lb/ton of diet); and 4-9) the control diet containing 1 of 6 experimental probiotics (DSM probiotic products 1-6; 4 lb/ton of diet). Dietary treatments were fed for 44 d with pen and feeder weights collected on d 0, 11, 18, 25, 32, 39 and 44. Pigs fed Mecadox had increased (P0.05). Pigs fed DSM probiotic product 4 had greater (P0.05) ADG and ADFI compared to those fed Bioplus 2B. No difference in d 44 BW was observed among any DSM probiotic product relative to the control, but pigs fed Mecadox or Bioplus 2B had increased (P<0.05) d 44 BW compared to those fed the control diet. In conclusion, adding an antimicrobial (Mecadox) to the diet resulted in the best growth performance. Pigs fed a commercial probiotic and one of the experimental probiotics had intermediate performance compared with the control and Mecadox fed pigs

PU(2) monopoles. II: Top-level Seiberg-Witten moduli spaces and Witten's conjecture in low degrees

In this article we complete the proof---for a broad class of four-manifolds---of Witten's conjecture that the Donaldson and Seiberg-Witten series coincide, at least through terms of degree less than or equal to c-2, where c is a linear combination of the Euler characteristic and signature of the four-manifold. This article is a revision of sections 4--7 of an earlier version, while a revision of sections 1--3 of that earlier version now appear in a separate companion article (math.DG/0007190). Here, we use our computations of Chern classes for the virtual normal bundles for the Seiberg-Witten strata from the companion article (math.DG/0007190), a comparison of all the orientations, and the PU(2) monopole cobordism to compute pairings with the links of level-zero Seiberg-Witten moduli subspaces of the moduli space of PU(2) monopoles. These calculations then allow us to compute low-degree Donaldson invariants in terms of Seiberg-Witten invariants and provide a partial verification of Witten's conjecture.Comment: Journal fur die Reine und Angewandte Mathematik, to appear; 65 pages. Revision of sections 4-7 of version v1 (December 1997

Validation of the Symptom Pattern Method for Analyzing Verbal Autopsy Data

Chris Murray and colleagues propose and, using data from China, validate a new strategy for analyzing verbal autopsy data that combines the advantages of previous methods

Associations of long chain polyunsaturated fatty acids with bone mineral density and bone turnover in postmenopausal women

PURPOSE: The immunomodulatory properties of n-3 long chain polyunsaturated fatty acids (LCPUFA) are reported to reduce bone loss through alteration of bone remodelling and n-3 LCPUFA, therefore, may benefit bone health in post-menopausal women, a vulnerable group at high risk of osteoporosis. METHODS: Measures of bone mineral density (BMD) were determined using dual energy X-ray absorptiometry (DEXA) in 300 post-menopausal women. The bone turnover markers osteocalcin (OC), C-terminal telopeptides of type 1 collagen (CTX) and total alkaline phosphatase were quantified in serum along with urinary creatinine corrected deoxypyridinoline (DPD/Cr) and CTX/Cr and the CTX:OC ratio calculated. Total serum n-6 PUFA (LA + AA) and n − 3 LCPUFA (ALA + EPA + DPA + DHA) were measured and the n − 6:n − 3 ratio was calculated. RESULTS: Mean (SD) age and body mass index (BMI) were 61 (6.4) years and 27.4 (4.8) kg/m(2), respectively with participants being 12.6 (7.6) years post-menopause. Multiple regression analysis identified no association between n-3 LCPUFA and any of the measures of T-score or BMD albeit a significant positive association between total n − 3 LCPUFA and femur BMD (β = 0.287; p = 0.043) was observed within those women with a low n − 6:n − 3 ratio. There was a significant inverse association between ALA and urinary DPD/Cr (β = − 0.141; p = 0.016). CONCLUSION: A favourable low n − 6:n − 3 ratio was associated with higher femur BMD and a higher n − 3 LCPUFA (ALA) was associated with lower bone resorption. These results support a beneficial role for n − 3 LCPUFA in reducing postmenopausal bone resorption and favourably influencing BMD. TRIAL NUMBER & DATE OF REGISTRATION: ISRCTN63118444, 2nd October 2009, “Retrospectively registered”

Do young children get the message? The effects of repeated video viewing on explicit and implicit information

The aim of this study was to explore the effects of repeat viewing on comprehension of explicitly and implicitly presented information in an animated movie. Seventy-three pre-school children watched an animated film and were tested for comprehension after either their single or fifth viewing. Only children&rsquo;s comprehension of explicitly presented information was facilitated by repeat viewing. However, post hoc analyses revealed that children&rsquo;s explicit and implicit comprehension of a central character Thunderbolt significantly increased across viewing conditions, whereas, repeat viewing only facilitated children&rsquo;s explicit comprehension of the central character Patch. The theoretical and practical implications of these findings are discussed.<br /