Mitochondrial DNA amplification success rate as a function of hair morphology

This study examines the amplification success rate of mitochondrial DNA from human head hair with respect to their potential for forensic application. Mitochondrial DNA was isolated using a Chelex-based extraction method and amplified using the LINEAR ARRAY duplex PCR system. The particular focus of this study was to characterize the morphological features of human head hair in order to further the understanding of the factors that influence amplification success rate in hair tissue using the LINEAR ARRAY duplex PCR system. 2554 head hairs from 132 individuals representing four population groups were amplified. The hair samples were characterized as follows: 1251 were identified microscopically as telogen hairs and 1303 were classified as hairs without roots (removed before extraction). Amplification success was assessed as a function of several independent variables: morphological characteristics; telogen root versus no root; donor age; scalp origin; use of cosmetic hair treatments; and race of the donor. The results show that a positive correlation exists between amplification success and the presence of a telogen root. Combining the amplification success with either the original or optimized protocol, telogen hairs result in an overall success rate of 77.5% compared with 65% for hairs with no roots. Controlling for telogen hairs, the findings indicate that the overall success rate is independent of cosmetic hair treatments; medulla structure; shaft length, diameter, and volume; and scalp origin. Conversely, the age of the donor, the race of the donor, and hair pigmentation all contribute to a variation in amplification success rate.     

Using Gas Chromatography with Ion Mobility Spectrometry to Resolve Explosive Compounds in the Presence of Interferents*

Abstract: Ion mobility spectrometry (IMS) is a valued field detection technology because of its speed and high sensitivity, but IMS cannot easily resolve analytes of interest within mixtures. Coupling gas chromatography (GC) to IMS adds a separation capability to resolve complex matrices. A GC‐IONSCAN^® operated in IMS and GC/IMS modes was evaluated with combinations of five explosives and four interferents. In 100 explosive/interferent combinations, IMS yielded 21 false positives while GC/IMS substantially reduced the occurrence of false positives to one. In addition, the results indicate that through redesign or modification of the preconcentrator there would be significant advantages to using GC/IMS, such as enhancement of the linear dynamic range (LDR) in some situations. By balancing sensitivity with LDR, GC/IMS could prove to be a very advantageous tool when addressing real world complex mixture situations.     

改革以来中国农民工流动机制变迁的考察

改革开放以来中国农民工流动机制变迁经历三个基本阶段：1978-1992年以乡镇企业发展为主体的产业流动机制建设时期;1992-2002年以国企改制和非公经济发展为主体的社会主义市场经济机制建设时期;2002年至今以科学发展观为指导的城乡一体发展体制建设时期。其基本特点与历史经验是：第一,家庭联产承包责任制与社会主义市场经济体制搭建了农民工流动机制的基本框架。第二,从城乡二元流动机制走向城乡一体流动机制。第三,从产业流动机制到地域流动机制有序放开。第四,在城市流动机制中,以沿海城市与中小城市为吸纳主体。农民工市民化以小城镇为吸纳主体。改革以来农民工流动机制变迁,积累了宝贵的经验,也留下了深刻的启示。     

Testing the Hollowing-Out Thesis

In recent years, many economists have argued that governments are discarding pegged exchange rates in favor of alternative exchange rate regimes such as monetary unions and currency boards on the one hand, or floating exchange rates on the other. Capital mobility, such economists argue, has made pegged exchange rates costly to maintain for long periods, and thus the pegging option is being “hollowed-out.” Few, however, have tried to present evidence that capital mobility has a direct effect on exchange rate regime choices. I present two sets of tests using different measures of capital mobility that provide qualified confirmation that developing countries peg less as capital mobility rises. These tests indicate that direct measures of capital mobility have some correlation with de facto exchange rate regimes but not with de jure exchange rate regimes. Capital flows, a consequence of capital mobility, may have a direct effect on the choices of both de jure and de facto regimes. Governments do not make changes in their declared exchange rate policies in rational anticipation of the growing costs of pegging associated with increasing capital mobility. Rather, governments normally adapt their declared exchange rate policies after capital flows have increased and actual exchange rates have become more difficult to manage. The tests also indicate that hollowing-out has not only been the result of systemic factors such as increasing capital mobility and capital flows, but also due to domestic factors such as growing public sector indebtedness and the spread of democracy.     

30个中低突变Y-STR基因座复合扩增体系的建立

目的建立30个中低突变Y-STR基因座的复合扩增体系,并对其性能进行评估。方法采用六色荧光标记技术,选择30个中低突变率、中高多态性的Y-STR基因座自行设计引物,进行复合扩增和毛细管电泳检测。检测该体系的准确性、特异性、灵敏度和耐受性,并观察其在混合检材的分型情况。结果采用本体系,分型结果准确稳定、特异性好、耐受性强,灵敏度达0.0625ng,混合检材在1:4的比例下,可获准确分型。结论本研究建立的30个Y-STR基因座的复合扩增体系分型结果良好,对于中国人群的法医Y-STR数据库建设和群体遗传学研究具有重要意义。     

Observing FDI spillover transmission channels: evidence from firms in Uganda

Abstract

We observe and analyse three intra-industry foreign direct investment (FDI) spillover transmission channels using unique firm-level data collected from on-site interviews and observations regarding domestic and foreign firms operating in Uganda in 2015. Our main results are: (1) the spillover effects mainly depend on the channel(s) by which they occur (the competition channel is most important while spillover benefits through the worker mobility and the imitation channels are less prevalent) and (2) both positive and negative spillover effects occur within the same channel and, moreover, effects differ by channel for the same case. These are novel and challenging findings that have not yet been recognised in theoretical and empirical research on FDI spillovers. Our results suggest that long-term pecuniary spillover effects are predominantly stimulated via the competition channel and show that only limited short-term and long-term technological spillover effects occur through the imitation and the movement of workers channels. These channels are not only less prevalent, but also appear to be constrained by competition-determined spillovers. We are confident that these directions for future research will have a high pay-off because, as shown by this exploratory fieldwork, a more complete picture of the spillover effects is reached when the channels are considered simultaneously.     

同色电工胶带的光谱成像技术检验

目的研究同种颜色电工胶带的区分方法。方法应用光谱成像技术对同色（选取红、黄、蓝、绿4种颜色）不同品牌的电工胶带进行区分。结果蓝色电工胶带的区分率最高,达到99.0%,红色、绿色、黄色样品的区分率相差不大,分别为94.3%、93.8%及93.3%。结论光谱成像技术可以实现同种颜色电工胶带的快速区分,从色度学角度为法庭科学领域电工胶带物证的区分提供了一种新的方法。     

GC-HPLC法考察圆珠笔字迹油墨厚度对溶剂挥发速率的影响

目的考察圆珠笔字迹油墨厚度对溶剂挥发速率的影响。方法采用GC/HPLC联用技术对不同时间、不同字迹油墨厚度在同种纸张上的圆珠笔油墨字迹中的溶剂、染料成分的定量分析。结果字迹油墨较厚的苯甲醇、苯氧基乙醇的含量随时间的变化比字迹油墨较薄的慢。结论字迹油墨的厚度对溶剂的挥发速率影响较大。     

Developmental validation of 15 X chromosomal short tandem repeat markers

The use of X chromosomal short tandem repeat (STR) markers has been greatly increasing in the forensic setting. Using guidelines set forth previously for the validation of autosomal and Y STRs, aspects of the feasibility of routine X chromosomal STR use were evaluated. Two mini-X chromosomal STR multiplexes capable of amplifying 15 total markers were developed and utilized to determine allele nomenclature, allele/genotype frequencies, mutation rates, and linkage between markers. Additionally, a concordance study between these multiplexes and a commercially available kit was performed. Here, the authors present an overview of this extensive developmental validation study.     

More Than Meets the Market? Landlord Agency in the Illinois Housing Choice Voucher Program

The federal Housing Choice Voucher Program currently serves as one of the nation's predominant strategies for providing affordable rental housing for low-income households. The program is designed around two goals: first, to uphold the U.S. Department of Housing and Urban Development's mission to provide safe, decent, and affordable housing; and second, to facilitate household residential location choices, with the idea that such choices can leverage other types of nonhousing opportunities for assisted households. While scholarly research has described a range of positive and negative household outcomes associated with the voucher subsidy, less is known about how those outcomes are produced on the ground. This research describes findings from 72 in-depth interviews with Illinois landlords and other voucher program stakeholders regarding their experiences with the program, with the goal of linking landlord practices to tenant outcomes. Findings of this research underscore the substantial influence that landlords have on assisted-household residential location choice and tenure, and show the potential for voucher program design to more actively engage with landlords as providers of supports that extend beyond the housing unit.