Landscape change in central Latvia since the Iron Age: multi-proxy analysis of the vegetation impact of conflict, colonization and economic expansion during the last 2000 years

This study represents the first detailed multi-proxy palaeoenvironmental investigation associated with a Late Iron Age lake-dwelling site in the eastern Baltic. The main objective was to reconstruct the environmental and vegetation dynamics associated with the establishment of the lake-dwelling and land-use during the last 2,000 years. A lacustrine sediment core located adjacent to a Late Iron Age lake-dwelling, medieval castle and Post-medieval manor was sampled in Lake Āraiši. The core was dated using spheroidal fly-ash particles and radiocarbon dating, and analysed in terms of pollen, non-pollen palynomorphs, diatoms, loss-on-ignition, magnetic susceptibility and element geochemistry. Associations between pollen and other proxies were statistically tested. During ad 1–700, the vicinity of Lake Āraiši was covered by forests and human activities were only small-scale with the first appearance of cereal pollen (Triticum and Secale cereale) after ad 400. The most significant changes in vegetation and environment occurred with the establishment of the lake-dwelling around ad 780 when the immediate surroundings of the lake were cleared for agriculture, and within the lake there were increased nutrient levels. The highest accumulation rates of coprophilous fungi coincide with the occupation of the lake-dwelling from ad 780–1050, indicating that parts of the dwelling functioned as byres for livestock. The conquest of tribal lands during the crusades resulted in changes to the ownership, administration and organisation of the land, but our results indicate that the form and type of agriculture and land-use continued much as it had during the preceding Late Iron Age.

Stalagmite water content as a proxy for drip water supply in tropical and subtropical areas

In this pilot study water was extracted from samples of two Holocene stalagmites from Socotra Island, Yemen, and one Eemian stalagmite from southern continental Yemen. The amount of water extracted per unit mass of stalagmite rock, termed "water yield" hereafter, serves as a measure of its total water content. Based on direct correlation plots of water yields and δ18Ocalcite and on regime shift analyses, we demonstrate that for the studied stalagmites the water yield records vary systematically with the corresponding oxygen isotopic compositions of the calcite (δ18Ocalcite). Within each stalagmite lower δ18Ocalcite values are accompanied by lower water yields and vice versa. The δ18Ocalcite records of the studied stalagmites have previously been interpreted to predominantly reflect the amount of rainfall in the area; thus, water yields can be linked to drip water supply. Higher, and therefore more continuous drip water supply caused by higher rainfall rates, supports homogeneous deposition of calcite with low porosity and therefore a small fraction of water-filled inclusions, resulting in low water yields of the respective samples. A reduction of drip water supply fosters irregular growth of calcite with higher porosity, leading to an increase of the fraction of water-filled inclusions and thus higher water yields. The results are consistent with the literature on stalagmite growth and supported by optical inspection of thin sections of our samples. We propose that for a stalagmite from a dry tropical or subtropical area, its water yield record represents a novel paleo-climate proxy recording changes in drip water supply, which can in turn be interpreted in terms of associated rainfall rates.

The impact of the abrupt 8.2 ka cold event on the Mesolithic population of western Scotland: a Bayesian chronological analysis using ‘activity events’ as a population proxy

The potential impact of the abrupt 8.2 ka cold event on human demography, settlement patterns and culture in Europe and the Near East has emerged as a key theme in current discussion and debate. We test whether this event had an impact on the Mesolithic population of western Scotland, a case study located within the North Atlantic region where the environmental impact of the 8.2 ka event is likely to have been the most severe. By undertaking a Bayesian analysis of the radiocarbon record and using the number of activity events as a proxy for the size of the human population, we find evidence for a dramatic reduction in the Mesolithic population synchronous with the 8.2 ka event. We interpret this as reflecting the demographic collapse of a low density population that lacked the capability to adapt to the rapid onset of new environmental conditions. This impact of the 8.2 ka event in the North Atlantic region lends credence to the possibility of a similar impact on populations in Continental Europe and the Near East.

Proxy re-encryption schemes for IoT and crowd sensing

IoT, crowd sensing and smart cities will be a traffic challenge. New communication paradigms as asynchronous messaging carry and forward, scheduled delivery and temporary storage will be needed to manage network resources dynamically. Since traditional end to end security will require keeping security associations among devices for a long time draining valuable resources, we propose and evaluate the use of proxy re-encryption protocols in these scenarios as a solution for reliable and flexible security.

A Note on Proxy Variables and Instrument Variable Regression

This is a note about proxy variables and instruments for identification of structural parameters in regression models. We have experienced that in the econometric textbooks these two issues are treated separately, although in practice these two concepts are very often combined. Usually, proxy variables are inserted in instrument variable regressions with the motivation they are exogenous. Implicitly meaning they are exogenous in a reduced form model and not in a structural model. Actually if these variables are exogenous they should be redundant in the structural model, e.g. IQ as a proxy for ability. Valid proxies reduce unexplained variation and increases the efficiency of the estimator of the structural parameter of interest. This is especially important in situations when the instrument is weak. With a simple example we demonstrate what is required of a proxy and an instrument when they are combined. It turns out that when a researcher has a valid instrument the requirements on the proxy variable is weaker than if no such instrument exists

Understanding the role of mediating risk factors and proxy effects in the association between socio-economic status and untreated hypertension

The association between socio-economic status (SES) and untreated hypertension varies according to a country's level of development and racial/ethnic group. We sought to confirm this variation in women from China and the United States (US) as well as to investigate the impact of SES on several mediating risk factors. We also investigate the extent to which SES explains racial/ethnic differences in untreated hypertension in the US. We used cross-sectional data from 1814 non-pregnant women in China (China Health and Nutrition Survey (CHNS), 1997) and 3266 non-pregnant women in the United States (National Health and Nutrition Examination Survey (NHANES III), 1988–1994) respectively. A variety of statistical modelling techniques was used to predict untreated hypertension as a function of several mediating factors and to simulate the impact of changes in SES. The age-adjusted prevalence of untreated hypertension was significantly higher (p<0.01) for low-income White and Black women compared to Mexican American or Chinese women. Untreated hypertension was not significantly associated with income or education in Mexican Americans or women in China. Obesity and light physical activity had the largest mediating effect on the association between SES and untreated hypertension for all racial/ethnic groups. However, this effect was not as strong as the proxy effect of income and education. SES did not completely explain racial/ethnic differences in hypertension in the US. While SES was more strongly associated with hypertension in Blacks than Whites, Blacks were still 1.97 (95% CI 1.47–2.64) times more likely to have untreated hypertension than Whites after adjusting for SES differences. The association between SES and untreated hypertension varied by country and racial/ethnic group. An important explanation for this variation was the differential effect of SES on mediating risk factors. SES disparities between Whites and Blacks in the US partly explain differences in the prevalence of untreated hypertension between these racial/ethnic groups.

Parent-proxy and child self-reported health-related quality of life: using qualitative methods to explain the discordance

Background: Although parent-proxy reports of health-related quality of life (HRQOL) are only moderately correlated with child reported HRQOL, it remains unknown why these scores differ. The aim of this study was to use a qualitative methodology to examine why parents and children report different levels of HRQOL.

Method: The sample consisted of 15 parent–child pairs. A think-aloud technique was used where parents and children were given a generic HRQOL instrument (KIDSCREEN) and instructed to share their thoughts with the interviewer. Qualitative analyses were conducted to assess whether parents and children base their answer on different experiences or reasoning, have different response styles, or interpret the items differently.

Results: There was discordance between parents and children, in terms of rating scale and in terms of the reasoning for their answer. Children tended to have different response styles to parents, where for example, children tended to provide extreme scores (highest or lowest score) and base their response on one single example, more than parents. Parents and children interpreted the meaning of the items very similarly.

Discussion: This study provides evidence to suggest that discordance among parent-child pairs on KIDSCREEN scores may be as a result of different reasoning and different response styles, rather than interpretation of items. These findings have important implications when parent-proxy reported HRQOL is used to guide clinical/treatment decisions.

Resisting web proxy-based HTTP attacks by temporal and spatial locality behavior

A novel server-side defense scheme is proposed to resist the Web proxy-based distributed denial of service attack. The approach utilizes the temporal and spatial locality to extract the behavior features of the proxy-to-server traffic, which makes the scheme independent of the traffic intensity and frequently varying Web contents. A nonlinear mapping function is introduced to protect weak signals from the interference of infrequent large values. Then, a new hidden semi-Markov model parameterized by Gaussian-mixture and Gamma distributions is proposed to describe the time-varying traffic behavior of Web proxies. The new method reduces the number of parameters to be estimated, and can characterize the dynamic evolution of the proxy-to-server traffic rather than the static statistics. Two diagnosis approaches at different scales are introduced to meet the requirement of both fine-grained and coarse-grained detection. Soft control is a novel attack response method proposed in this work. It converts a suspicious traffic into a relatively normal one by behavior reshaping rather than rudely discarding. This measure can protect the quality of services of legitimate users. The experiments confirm the effectiveness of the proposed scheme.

Effects of asenapine in bipolar I patients meeting proxy criteria for moderate-to-severe mixed major depressive episodes: a post hoc analysis

OBJECTIVE: Depression is the predominant psychosocial and suicide burden in bipolar disorder, yet there is a paucity of evidence-based treatments for bipolar depression. METHODS: This post hoc subgroup analysis of data pooled from two 3-week, randomized, placebo- and olanzapine-controlled trials (December 2004-April 2006, N = 489 and November 2004-April 2006, N = 488) examined a subgroup of patients meeting criteria for moderate-to-severe mixed major depressive episodes, defined using DSM-IV-TR criteria for mixed episodes (mania and major depression simultaneously) with a baseline Montgomery-Asberg Depression Rating Scale (MADRS) total score ≥ 20. RESULTS: Decreases in MADRS scores (least squares mean [SE]), the a priori primary outcome, were significantly greater in the asenapine group than in the placebo group from baseline to day 7 (-11.02 [1.82] vs -4.78 [1.89]; P = .0195), day 21 (-14.03 [2.01] vs -7.43 [2.09]; P = .0264), and endpoint (-10.71 [1.76] vs -5.19 [1.98]; P = .039). Decreases in MADRS scores with asenapine were significantly greater than with olanzapine from baseline to day 7 (-6.26 [1.47]; P = .0436). Decreases in Young Mania Rating Scale mean total score were greater with asenapine than with placebo or olanzapine at all time points assessed. A significantly greater reduction from baseline to day 21 in the Short Form-36 mental component summary score was observed with asenapine, but not olanzapine, compared with placebo (16.57 vs 5.97; P = .0093). Asenapine was generally well tolerated. CONCLUSIONS: These data provide support for the potential efficacy of asenapine in mixed major depressive episodes; however, these data cannot be linearly extrapolated to nonmixed major depression.