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291.
This article examines debt peonage in the state of Chiapas in southern Mexico during the regime of Porfirio Díaz (1876–1911). It argues that debt peonage in Chiapas was a coercive institution, which served to cheapen the price of labour in the growing agricultural export sector. Thus, rather than a ‘feudal relic’ incompatible with the logic of capitalist efficiency, the expansion and intensification of debt peonage during this time was consistent with the political economy of capitalist modernization in Mexico prior to the revolution of 1910–20.  相似文献   
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The goal of this study was to investigate the relationship between the perceived frequency and perceived importance of social support with youth’s self-concept. Data from a large representative sample of 921 children and adolescents in grades 3 through 12 were analyzed. Results indicated that the relationships between the frequency of social support from parents, teachers, classmates, and close friends with self-concept were significant. However, only the perceived importance of social support from teachers was significantly related to self-concept. Finally, an interaction was found between the frequency of social support and the importance of social support from classmates and close friends on self-concept. These results suggest that self-evaluations of the importance of teacher support may be especially influential for youths’ self-concept, and that the ability to discount the value of support from classmates and friends, when it is lacking, may be protective to the self-concept of children and adolescents.
Michelle Kilpatrick DemarayEmail:
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Optical tweezers have a wide range of uses for mechanical manipulation of objects in the microscopic range. This includes both living and static cells in a variety of biomedical and research applications. Single-focus optical tweezers, formed by focusing a laser beam through a high numerical aperture immersion objective, create a significant force, which enables controlled transport of a variety of different cell types and morphologies in three dimensions. Optical tweezers have been previously reported to capture and separate spermatozoa from a reconstituted simulated postcoital sample. We report herein the development of a simplified, more efficient cell transfer protocol that can separate and isolate both spermatozoa as well as leukocytes, with similar efficiencies as those previously reported. The new cell transfer method was used to separate sperm cells from a reconstituted mixture of spermatozoa and vaginal epithelial cells, with complete STR profiles developed from 50 cells with little evidence of contribution from the female contributor to the mixture. This modified protocol was then used to separate 21 samples of enriched leukocytes, with trapped cells ranging from 5 to 22 cells. Complete STR profiles were developed from as few as 10 leukocytes. Thus, with minimal sample preparation and a short trapping time, this method has the potential to provide an alternative to traditional differential extraction methods for separation of sperm:nonsperm mixtures while also providing versatility for separation of cells with differing morphologies.  相似文献   
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The collection, storage, and transport of samples prior to and during analysis is of utmost importance, especially for highly potent analogs that may not be present in high concentrations and are susceptible to pH or thermally mediated degradation. An accelerated stability study was performed on 17 fentanyl analogs (fentalogs) over a wide range of pH (2–10) and temperature (20–60°C) conditions over 24 h. Dilute aqueous systems were used to investigate temperature and pH-dependent kinetics using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Liquid chromatography-quadrupole/time-of-flight-mass spectrometry (LC-Q/TOF–MS) was used for structural elucidation of degradants. With the exception of remifentanil, all fentalogs evaluated were stable at pH 6 or lower. Fentalogs were generally unstable in strongly alkaline environments and at elevated temperatures. Remifentanil was the least stable drug and N-dealkylated fentalogs were the most stable. Fentanyl degraded to acetylfentanyl, norfentanyl, fentanyl N-oxide, and 1-phenethylpyridinium salt (1-PEP). A total of 26 unique breakdown products were observed for 15 of the fentanyl derivatives studied. Common degradation pathways involved N-dealkylation, oxidation of the piperidine nitrogen, and β-elimination of N-phenylpropanamide followed by oxidation/dehydration of the piperidine ring. Ester and amide hydrolysis, demethylation at the propanamide, and O-demethylation were observed for selected fentalogs only. The potential for analyte loss should be considered during the pre-analytical phase (i.e., shipping and transport) where environmental conditions may not be controlled, as well as during the analysis itself.  相似文献   
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Governments have increasingly tasked the not-for-profit sector with supporting the provision of public goods and services. Alongside this role, not-for-profits have faced increasingly challenging external contexts, including heightened competition and tighter funding regimes. This makes effective innovation critical for the successful delivery of social goods within this setting particularly, and in other public service-oriented organisations more broadly. However, we know little about how innovation occurs in such contexts and even less about the motivations of those who choose to expend the effort to drive innovation there. This study examines the motivations of a key innovation agent, the innovation champion, in the challenging and dynamic not-for-profit context. Via a multi-case study, qualitative approach with 46 interviews, we utilise self-determination theory to surface what motivates innovation champions to develop and drive new idea generation and implementation. The motivations for championing innovations in not-for-profits are varied, spanning intrinsic, prosocial, and other extrinsic drivers. With wider implications for public service-oriented organisations, our work also suggests that champions in such contexts are variably motivated throughout an innovation project and appear to be simultaneously intrinsically and prosocially motivated. We also find that boredom, or its avoidance, can motivate champions toward innovative activities.  相似文献   
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