Search

Not all policy questions can be addressed by social experiments. Nonexperimental evaluation methods provide an alternative to experimental designs but their results depend on untestable assumptions. This paper presents evidence on the reliability of propensity score matching (PSM), which estimates treatment effects under the assumption of selection on observables, using a social experiment designed to evaluate the PROGRESA program in Mexico. The authors find that PSM performs well for outcomes that are measured comparably across survey instruments and when a rich set of control variables is available. However, even small differences in the way outcomes are measured can lead to bias in the technique.

As humans are the primary geomorphic agents on the landscape, it is essential to assess the magnitude, chronological span, and future effects of artificial ground that is expanding under modern urbanization at an alarming rate. We argue humans have been primary geomorphic agents of landscapes since the rise of early urbanism that continue to structure our everyday lives. Past and present anthropogenic actions mold a dynamic "taskscape" (not just a landscape) onto the physical environment. For example, one of the largest Pre-Columbian metropolitan centers of the New World, the UNESCO world heritage site of Teotihuacan, demonstrates how past anthropogenic actions continue to inform the modern taskscape, including modern street and land alignments. This paper applies a multi-scalar, long durée approach to urban landscapes utilizing the first lidar map of the Teotihuacan Valley to create a geospatial database that links modern and topographic features visible on the lidar map with ground survey, historic survey, and excavation data. Already, we have recorded not only new features previously unrecognized by historic surveys, but also the complete erasure of archaeological features due to modern (post-2015) mining operations. The lidar map database will continue to evolve with the dynamic landscape, able to assess continuity and changes on the Teotihuacan Valley, which can benefit decision makers contemplating the stewardship, transformation, or destruction of this heritage landscape. [ABSTRACT FROM AUTHOR]

The application of lidar remote-sensing technology has revolutionized the practice of settlement and landscape archaeology, perhaps nowhere more so than in the Maya lowlands. This contribution presents a substantial lidar dataset from the Puuc region of Yucatan, Mexico, a cultural subregion of the ancient Maya and a distinct physiographic zone within the Yucatan peninsula. Despite the high density of known sites, no large site has been fully surveyed, and little is known about intersite demography. Lidar technology allows determination of settlement distribution for the first time, showing that population was elevated but nucleated, although without any evidence of defensive features. Population estimates suggest a region among the most densely settled within the Maya lowlands, though hinterland levels are modest. Lacking natural bodies of surface water, the ancient Puuc inhabitants relied upon various storage technologies, primarily chultuns (cisterns) and aguadas (natural or modified reservoirs for potable water). Both are visible in the lidar imagery, allowing calculation of aguada capacities by means of GIS software. The imagery also demonstrates an intensive and widespread stone working industry. Ovens visible in the imagery were probably used for the production of lime, used for construction purposes and perhaps also as a softening agent for maize. Quarries can also be discerned, including in some cases substantial portions of entire hills. With respect to agriculture, terrain classification permits identification of patches of prime cultivable land and calculation of their extents. Lidar imagery also provides the first unequivocal evidence for terracing in the Puuc, indeed in all northern Yucatan. Finally, several types of civic architecture and architectural complexes are visible, including four large acropolises probably dating to the Middle Formative period (700–450 B.C.). Later instances of civic architecture include numerous Early Puuc Civic Complexes, suggesting a common form of civic organization at the beginning of the Late Classic demographic surge, (A.D. 600–750). [ABSTRACT FROM AUTHOR]

We present results from the archaeological analysis of 331 km2 of high-resolution airborne lidar data collected in the Upper Usumacinta River basin of Mexico and Guatemala. Multiple visualizations of the DEM and multi-spectral data from four lidar transects crossing the Classic period (AD 350–900) Maya kingdoms centered on the sites of Piedras Negras, La Mar, and Lacanja Tzeltal permitted the identification of ancient settlement and associated features of agricultural infrastructure. HDBSCAN (hierarchical density-based clustering of applications with noise) cluster analysis was applied to the distribution of ancient structures to define urban, peri-urban, sub-urban, and rural settlement zones. Interpretations of these remotely sensed data are informed by decades of ground-based archaeological survey and excavations, as well as a rich historical record drawn from inscribed stone monuments. Our results demonstrate that these neighboring kingdoms in three adjacent valleys exhibit divergent patterns of structure clustering and low-density urbanism, distributions of agricultural infrastructure, and economic practices during the Classic period. Beyond meeting basic subsistence needs, agricultural production in multiple areas permitted surpluses likely for the purposes of tribute, taxation, and marketing. More broadly, this research highlights the strengths of HDBSCAN to the archaeological study of settlement distributions when compared to more commonly applied methods of density-based cluster analysis. [ABSTRACT FROM AUTHOR]

Objective This study investigated the prevalence of eating disorders (ED) in women. Method Two samples of university students (1995, n = 522; 2002, n = 880) completed the Eating Attitudes Test and the Bulimia Test (BULIT; Stage 1). During Stage 2, the women that exceeded the cut-off point of one or both questionnaires and a random sample of women that did not exceed the cut-off point were interviewed. Results The results showed a prevalence rate of 0.49% for ED in 1995 (0.14% for bulimia nervosa [BN] and 0.35% for EDs not otherwise specified [EDNOS]) and a prevalence rate of ED of 1.15% in 2002 (0.24% for BN and 0.91% for EDNOS). Anorexia nervosa was not found in either of the evaluated periods. Nevertheless, the results must be taken with reservation since there was a high rate of loss to follow-up (second stage). Discussion The data of this study support the findings of other studies, including studies with Spanish-speaking samples, that EDNOS is the most common ED followed by BN and AN. Copyright © 2007 John Wiley & Sons, Ltd and Eating Disorders Association. [ABSTRACT FROM AUTHOR]

Objective. To examine the determinants of the utilization of health care services among the population of older adults in Mexico. Three types of health care services are analyzed: preventive care, visits to the doctor, and hospitalizations. Material and Methods. Data was used from the 2001 Mexican Health and Aging Study (MHAS/ENASEM) and estimates were made using multivariate probit regression methods. Results. Socioeconomic factors, health conditions reported by the individuals, and the availability of health insurance are significant determinants of the differential use of services by older adults. Conclusion. Specific health conditions are important determinants of use of the various types of health care services. For all three types, however, the availability of health insurance is an enabling factor of health care use. Older age is associated with greater propensity to use health care services but its effect is small when controlling for health conditions. [ABSTRACT FROM AUTHOR]

Not all policy questions can be addressed by social experiments. Nonexperimental evaluation methods provide an alternative to experimental designs but their results depend on untestable assumptions. This paper presents evidence on the reliability of propensity score matching (PSM), which estimates treatment effects under the assumption of selection on observables, using a social experiment designed to evaluate the PROGRESA program in Mexico. We find that PSM performs well for outcomes that are measured comparably across survey instruments and when a rich set of control variables is available. However, even small differences in the way outcomes are measured can lead to bias in the technique. [ABSTRACT FROM AUTHOR]

Marine obligate actinobacteria produce a wide variety of secondary metabolites with biological activity, notably those with antibiotic activity urgently needed against multi-drug-resistant bacteria. Seventy-five marine actinobacteria were isolated from a marine sediment sample collected in Punta Arena de La Ventana, Baja California Sur, Mexico. The 16S rRNA gene identification, Multi Locus Sequence Analysis, and the marine salt requirement for growth assigned seventy-one isolates as members of the genus Salinispora , grouped apart but related to the main Salinispora arenicola species clade. The ability of salinisporae to inhibit bacterial growth of Staphylococcus epidermidis, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacer baumannii, Pseudomonas aeruginosa , and Enterobacter spp. was evaluated by cross-streaking plate and supernatant inhibition tests. Ten supernatants inhibited the growth of eight strains of S. epidermidis from patients suffering from ocular infections, two out of the eight showed growth inhibition on ten S. epidermidis strains from prosthetic joint infections. Also, it inhibited the growth of the remaining six multi-drug-resistant bacteria tested. These results showed that some Salinispora strains could produce antibacterial compounds to combat bacteria of clinical importance and prove that studying different geographical sites uncovers untapped microorganisms with metabolic potential., Competing Interests: Conflict of interest The authors do not report any financial or personal connections with other persons or organizations, which might negatively affect the contents of this publication and/or claim authorship rights to this publication., (© 2020 Luis Contreras-Castro et al.)

Archaeologists have traditionally thought that the development of Maya civilization was gradual, assuming that small villages began to emerge during the Middle Preclassic period (1000-350 BC; dates are calibrated throughout) along with the use of ceramics and the adoption of sedentism 1 . Recent finds of early ceremonial complexes are beginning to challenge this model. Here we describe an airborne lidar survey and excavations of the previously unknown site of Aguada Fénix (Tabasco, Mexico) with an artificial plateau, which measures 1,400 m in length and 10 to 15 m in height and has 9 causeways radiating out from it. We dated this construction to between 1000 and 800 BC using a Bayesian analysis of radiocarbon dates. To our knowledge, this is the oldest monumental construction ever found in the Maya area and the largest in the entire pre-Hispanic history of the region. Although the site exhibits some similarities to the earlier Olmec centre of San Lorenzo, the community of Aguada Fénix probably did not have marked social inequality comparable to that of San Lorenzo. Aguada Fénix and other ceremonial complexes of the same period suggest the importance of communal work in the initial development of Maya civilization.

Introduction: The diabetes hospitalization rate for the region along the U.S. side of the U.S.-Mexico border is unknown, a situation that could limit the success of the Healthy Border 2010 program. To remedy this problem, we analyzed and compared hospital discharge data for Arizona, California, and Texas for the year 2000 and calculated the diabetes hospitalization rates., Methods: We obtained hospital-discharge public-use data files from the health departments of three U.S. border states and looked for cases of diabetes. Only when diabetes was listed as the first diagnosis on the discharge record was it considered a case of diabetes for our study. Patients with cases of diabetes were classified as border county (BC) or nonborder county (NBC) residents. Comparisons between age-adjusted diabetes discharge rates were made using the z test., Results: Overall, 1.2% (86,198) of the discharge records had diabetes listed as the primary diagnosis. BC residents had a significantly higher age-adjusted diabetes discharge rate than NBC residents. BC males had higher diabetes discharge rates than BC females or NBC males. In both the BCs and the NBCs, Hispanics had higher age-adjusted diabetes discharge rates than non-Hispanics., Conclusion: The results of this study provide a benchmark against which the effectiveness of the Healthy Border 2010 program can be measured.