Field investigation of dried lakes in western United States as an analogue to desiccation fractures on Mars

Potential Desiccation Polygons (PDPs), tens to hundreds of meters in size, have been observed in numerous regions on Mars, particularly in ancient (>3Gyr old) terrains of inferred paleolacustrine/playa geologic setting, and in association with hydrous minerals such as smectites. Therefore, a better understanding of the conditions in which large desiccation polygons form could yield unique insight into the ancient climate on Mars. Many dried lakebeds/playas in western United States display large (>50m wide) desiccation polygons, which we consider to be analogues for PDPs on Mars. Therefore, we have carried out fieldwork in seven of these dried lakes in San Bernardino and the Death Valley National Park regions complemented with laboratory and spectral analysis of collected samples. Our study shows that the investigated lacustrine/playa sediments have (a) a soil matrix containing 40-75% clays and fine silt (by volume) where the clay minerals are dominated by illite/muscovite followed by smectite, (b) carbonaceous mineralogy with variable amounts of chloride and sulfate salts, and significantly, (c) roughly similar spectral signatures in the visible-near-infrared (VIS-NIR) range. We conclude that the development of large desiccation fractures is consistent with water table retreat. In addition, the comparison of the mineralogical to the spectral observations further suggests that remote sensing VIS-NIR spectroscopy has its limitations for detailed characterization of lacustrine/playa deposits. Finally, our results imply that the widespread distribution of PDPs on Mars indicates global or regional climatic transitions from wet conditions to more arid ones making them important candidate sites for future in situ missions.

[Influence of the pelvic trauma registry of the DGU on treatment of pelvic ring fractures].

Fractures of the pelvic ring are comparatively rare with an incidence of 2-8 % of all fractures depending on the study in question. The severity of pelvic ring fractures can be very different ranging from simple and mostly "harmless" type A fractures up to life-threatening complex type C fractures. Although it was previously postulated that high-energy trauma was necessary to induce a pelvic ring fracture, over the past decades it became more and more evident, not least from data in the pelvic trauma registry of the German Society for Trauma Surgery (DGU), that low-energy minor trauma can also cause pelvic ring fractures of osteoporotic bone and in a rapidly increasing population of geriatric patients insufficiency fractures of the pelvic ring are nowadays observed with no preceding trauma.Even in large trauma centers the number of patients with pelvic ring fractures is mostly insufficient to perform valid and sufficiently powerful monocentric studies on epidemiological, diagnostic or therapeutic issues. For this reason, in 1991 the first and still the only registry worldwide for the documentation and evaluation of pelvic ring fractures was introduced by the Working Group Pelvis (AG Becken) of the DGU. Originally, the main objectives of the documentation were epidemiological and diagnostic issues; however, in the course of time it developed into an increasingly expanding dataset with comprehensive parameters on injury patterns, operative and conservative therapy regimens and short-term and long-term outcome of patients. Originally starting with 10 institutions, in the meantime more than 30 hospitals in Germany and other European countries participate in the documentation of data. In the third phase of the registry alone, which was started in 2004, data from approximately 15,000 patients with pelvic ring and acetabular fractures were documented. In addition to the scientific impact of the pelvic trauma registry, which is reflected in the numerous national and international publications, the dramatically changing epidemiology of pelvic ring fractures, further developments in diagnostics and the changes in operative procedures over time could be demonstrated. Last but not least the now well-established diagnostic and therapeutic algorithms for pelvic ring fractures, which could be derived from the information collated in registry studies, reflect the clinical impact of the registry.

The effects of long (C20/22) and short (C18) chain omega-3 fatty acids on keel bone fractures, bone biomechanics, behavior, and egg production in free-range laying hens.

Keel fractures in the laying hen are the most critical animal welfare issue facing the egg production industry, particularly with the increased use of extensive systems in response to the 2012 EU directive banning conventional battery cages. The current study is aimed at assessing the effects of 2 omega-3 (n3) enhanced diets on bone health, production endpoints, and behavior in free-range laying hens. Data was collected from 2 experiments over 2 laying cycles, each of which compared a (n3) supplemented diet with a control diet. Experiment 1 employed a diet supplemented with a 60:40 fish oil-linseed mixture (n3:n6 to 1.35) compared with a control diet (n3:n6 to 0.11), whereas the n3 diet in Experiment 2 was supplemented with a 40:60 fish oil-linseed (n3:n6 to 0.77) compared to the control diet (n3:n6 to 0.11). The n3 enhanced diet of Experiment 1 had a higher n3:n6 ratio, and a greater proportion of n3 in the long chain (C20/22) form (0.41 LC:SC) than that of Experiment 2 (0.12 LC:SC). Although dietary treatment was successful in reducing the frequency of fractures by approximately 27% in Experiment 2, data from Experiment 1 indicated the diet actually induced a greater likelihood of fracture (odds ratio: 1.2) and had substantial production detriment. Reduced keel breakage during Experiment 2 could be related to changes in bone health as n3-supplemented birds demonstrated greater load at failure of the keel, and tibiae and humeri that were more flexible. These results support previous findings that n3-supplemented diets can reduce fracture likely by increasing bone strength, and that this can be achieved without detriment to production. However, our findings suggest diets with excessive quantities of n3, or very high levels of C20/22, may experience health and production detriments. Further research is needed to optimize the quantity and type of n3 in terms of bone health and production variables and investigate the potential associated mechanisms.

Contribution of Genetic Background and Clinical Risk Factors to Low-Trauma Fractures in Human Immunodeficiency Virus (HIV)-Positive Persons: The Swiss HIV Cohort Study.

Background.  The impact of human genetic background on low-trauma fracture (LTF) risk has not been evaluated in the context of human immunodeficiency virus (HIV) and clinical LTF risk factors. Methods.  In the general population, 6 common single-nucleotide polymorphisms (SNPs) associate with LTF through genome-wide association study. Using genome-wide SNP arrays and imputation, we genotyped these SNPs in HIV-positive, white Swiss HIV Cohort Study participants. We included 103 individuals with a first, physician-validated LTF and 206 controls matched on gender, whose duration of observation and whose antiretroviral therapy start dates were similar using incidence density sampling. Analyses of nongenetic LTF risk factors were based on 158 cases and 788 controls. Results.  A genetic risk score built from the 6 LTF-associated SNPs did not associate with LTF risk, in both models including and not including parental hip fracture history. The contribution of clinical LTF risk factors was limited in our dataset. Conclusions.  Genetic LTF markers with a modest effect size in the general population do not improve fracture prediction in persons with HIV, in whom clinical LTF risk factors are prevalent in both cases and controls.