Climate variability in the subarctic area for the last 2 millennia

To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA) was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A similar to 16-30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas similar to 20-30- and similar to 50-90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice-temperature positive feedback.Peer reviewe

Wharton’s jelly-derived mesenchymal stromal cells as a promising cellular therapeutic strategy for the management of graft-versus-host disease

Citation: McGuirk, J. P., Robert Smith, J., Divine, C. L., Zuniga, M., & Weiss, M. L. (2015). Wharton’s jelly-derived mesenchymal stromal cells as a promising cellular therapeutic strategy for the management of graft-versus-host disease. Pharmaceuticals, 8(2), 196-220. doi:10.3390/ph8020196Allogeneic hematopoietic cell transplantation (allo-HCT), a treatment option in hematologic malignancies and bone marrow failure syndromes, is frequently complicated by Graft-versus-host disease (GVHD). The primary treatment for GVHD involves immune suppression by glucocorticoids. However, patients are often refractory to the steroid therapy, and this results in a poor prognosis. Therefore alternative therapies are needed to treat GVHD. Here, we review data supporting the clinical investigation of a novel cellular therapy using Wharton’s jelly (WJ)-derived mesenchymal stromal cells (MSCs) as a potentially safe and effective therapeutic strategy in the management of GVHD. Adult-derived sources of MSCs have demonstrated signals of efficacy in the management of GVHD. However, there are limitations, including: limited proliferation capacity; heterogeneity of cell sources; lengthy expansion time to clinical dose; expansion failure in vitro; and a painful, invasive, isolation procedure for the donor. Therefore, alternative MSC sources for cellular therapy are sought. The reviewed data suggests MSCs derived from WJ may be a safe and effective cellular therapy for GVHD. Laboratories investigated and defined the immune properties of WJ-MSCs for potential use in cellular therapy. These cells represent a more uniform cell population than bone marrow-derived MSCs, displaying robust immunosuppressive properties and lacking significant immunogenicity. They can be collected safely and painlessly from individuals at birth, rapidly expanded and stored cryogenically for later clinical use. Additionally, data we reviewed suggested licensing MSCs (activating MSCs by exposure to cytokines) to enhance effectiveness in treating GVHD. Therefore, WJCs should be tested as a second generation, relatively homogeneous allogeneic cell therapy for the treatment of GVHD. © 2015 by the authors; licensee MDPI, Basel, Switzerland

Assessing the performance of the BARCAST climate field reconstruction technique for a climate with long-range memory

The skill of the state-of-the-art climate field reconstruction technique BARCAST (Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time) to reconstruct temperature with pronounced long-range memory (LRM) characteristics is tested. A novel technique for generating fields of target data has been developed and is used to provide ensembles of LRM stochastic processes with a prescribed spatial covariance structure. Based on different parameter setups, hypothesis testing in the spectral domain is used to investigate if the field and spatial mean reconstructions are consistent with either the fractional Gaussian noise (fGn) process null hypothesis used for generating the target data, or the autoregressive model of order 1 (AR(1)) process null hypothesis which is the assumed temporal evolution model for the reconstruction technique. The study reveals that the resulting field and spatial mean reconstructions are consistent with the fGn process hypothesis for some of the tested parameter configurations, while others are in better agreement with the AR(1) model. There are local differences in reconstruction skill and reconstructed scaling characteristics between individual grid cells, and the agreement with the fGn model is generally better for the spatial mean reconstruction than at individual locations. Our results demonstrate that the use of target data with a different spatiotemporal covariance structure than the BARCAST model assumption can lead to a potentially biased climate field reconstruction (CFR) and associated confidence intervals.</p

Spatial distributions of perchloroethylene reactive transport parameters in the Borden Aquifer

We determined the descriptive statistical and spatial geostatistical properties of the perchloroethene ln Kd and the ln k of a 1.5 m thick by 10 m horizontal transect of the Borden aquifer near the location of the Stanford-Waterloo (SW) tracer experiment. The ln Kd distribution is not normal and is right skewed because of a few high values that occur localized in two regions of the transect. In contrast, the ln k data can be characterized by a normal distribution. A linear regression of ln Kd on ln k yields a statistically significant positive correlation, also shown at small lags in the cross correlogram. No significant vertical or horizontal trend in the ln Kd data was detected. The semivariogram ranges of ln k and ln Kd differ from one another in the vertical direction (0.33 ± 0.06 m and 0.20 ± 0.04 m, respectively) and are much less than the horizontal ranges (a few meters). Despite significant effort the horizontal range of ln Kd remains poorly characterized because of limitations of the sample locations. Many of the characteristics described above do not match those assumed in prior theoretical studies that examined the importance of various aquifer characteristics on SW tracer transport. We suggest that there is knowledge to be gained by revisiting the conclusions of these prior studies in light of the new information presented here

Physiotherapy Students’ Attitudes Toward Working With People With Dementia: A Cross-Sectional Survey

Aims: To understand personal, educational and clinical experiences and the attitudes of physiotherapy students towards people with dementia. Methods: Online survey questionnaire. Physiotherapy students in the last year of a two-year Masters of Physical Therapy (MPT) entry-to-practice degree program (n = 59) were surveyed. Descriptive statistics were used to analyze the data. Results: Fifty-five students participated (93%). The majority of students (n = 52/55, 77%) had at least one clinical placement working with people with dementia. Overall, 53% (n = 29/55) felt their academic training was sufficient to effectively work with people with dementia. Moreover, 82% (n = 45/55) reported their confidence was greatest working with people who could communicate well verbally. Conclusions: Disease-based knowledge was strong, yet just over half felt their academic training was sufficient to effectively work with people with dementia. The findings support the need for more training, particularly in communication strategies, to support students to effectively work with client with dementia upon graduation

Adaptive Optics Imaging of the AU Microscopii Circumstellar Disk: Evidence for Dynamical Evolution

We present an H-band image of the light scattered from circumstellar dust around the nearby (10 pc) young M star AU Microscopii (AU Mic, GJ 803, HD 197481), obtained with the Keck adaptive optics system. We resolve the disk both vertically and radially, tracing it over 17-60 AU from the star. Our AU Mic observations thus offer the possibility to probe at high spatial resolution (0.04" or 0.4 AU per resolution element) for morphological signatures of the debris disk on Solar-System scales. Various sub-structures (dust clumps and gaps) in the AU Mic disk may point to the existence of orbiting planets. No planets are seen in our H-band image down to a limiting mass of 1 M_Jup at >20 AU, although the existence of smaller planets can not be excluded from the current data. Modeling of the disk surface brightness distribution at H-band and R-band, in conjunction with the optical to sub-millimeter spectral energy distribution, allows us to constrain the disk geometry and the dust grain properties. We confirm the nearly edge-on orientation of the disk inferred from previous observations, and deduce an inner clearing radius <=10 AU. We find evidence for a lack of small grains in the inner (<60 AU) disk, either as a result of primordial disk evolution, or because of destruction by Poynting-Robertson and/or corpuscular drag. A change in the power-law index of the surface brightness profile is observed near 33 AU, similar to a feature known in the profile of the beta Pic circumstellar debris disk. By comparing the time scales for inter-particle collisions and Poynting-Robertson drag between the two systems, we argue that the breaks are linked to one of these two processes.Comment: 17 pages, 7 figures, 1 table; accepted by Ap

Arctic hydroclimate variability during the last 2000 years : current understanding and research challenges

Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydro-climate changes are expected to continue and possibly accelerate in the coming century, not only affecting pan-Arctic natural ecosystems and human activities, but also lower latitudes through the atmospheric and ocean circulations. However, a lack of spatiotemporal observational data makes reliable quantification of Arctic hydroclimate change difficult, especially in a long-term context. To understand Arctic hydroclimate and its variability prior to the instrumental record, climate proxy records are needed. The purpose of this review is to summarise the current understanding of Arctic hydroclimate during the past 2000 years. First, the paper reviews the main natural archives and proxies used to infer past hydroclimate variations in this remote region and outlines the difficulty of disentangling the moisture from the temperature signal in these records. Second, a comparison of two sets of hydroclimate records covering the Common Era from two data-rich regions, North America and Fennoscandia, reveals inter- and intra-regional differences. Third, building on earlier work, this paper shows the potential for providing a high-resolution hydroclimate reconstruction for the Arctic and a comparison with last-millennium simulations from fully coupled climate models. In general, hydroclimate proxies and simulations indicate that the Medieval Climate Anomaly tends to have been wetter than the Little Ice Age (LIA), but there are large regional differences. However, the regional coverage of the proxy data is inadequate, with distinct data gaps in most of Eurasia and parts of North America, making robust assessments for the whole Arctic impossible at present. To fully assess pan-Arctic hydroclimate variability for the last 2 millennia, additional proxy records are required.Peer reviewe

Targeting the Blood-Brain Barrier to Prevent Sepsis-Associated Cognitive Impairment

Sepsis is a systemic inflammatory disease resulting from an infection. This disorder affects 750 000 people annually in the United States and has a 62% rehospitalization rate. Septic symptoms range from typical flu-like symptoms (eg, headache, fever) to a multifactorial syndrome known as sepsis-associated encephalopathy (SAE). Patients with SAE exhibit an acute altered mental status and often have higher mortality and morbidity. In addition, many sepsis survivors are also burdened with long-term cognitive impairment. The mechanisms through which sepsis initiates SAE and promotes long-term cognitive impairment in septic survivors are poorly understood. Due to its unique role as an interface between the brain and the periphery, numerous studies support a regulatory role for the blood-brain barrier (BBB) in the progression of acute and chronic brain dysfunction. In this review, we discuss the current body of literature which supports the BBB as a nexus which integrates signals from the brain and the periphery in sepsis. We highlight key insights on the mechanisms that contribute to the BBB’s role in sepsis which include neuroinflammation, increased barrier permeability, immune cell infiltration, mitochondrial dysfunction, and a potential barrier role for tissue non-specific alkaline phosphatase (TNAP). Finally, we address current drug treatments (eg, antimicrobials and intravenous immunoglobulins) for sepsis and their potential outcomes on brain function. A comprehensive understanding of these mechanisms may enable clinicians to target specific aspects of BBB function as a therapeutic tool to limit long-term cognitive impairment in sepsis survivors

Platelet Ice Under Arctic Pack Ice in Winter

The formation of platelet ice is well known to occur under Antarctic sea ice, where subice platelet layers form from supercooled ice shelf water. In the Arctic, however, platelet ice formation has not been extensively observed, and its formation and morphology currently remain enigmatic. Here, we present the first comprehensive, long‐term in situ observations of a decimeter thick subice platelet layer under free‐drifting pack ice of the Central Arctic in winter. Observations carried out with a remotely operated underwater vehicle (ROV) during the midwinter leg of the MOSAiC drift expedition provide clear evidence of the growth of platelet ice layers from supercooled water present in the ocean mixed layer. This platelet formation takes place under all ice types present during the surveys. Oceanographic data from autonomous observing platforms lead us to the conclusion that platelet ice formation is a widespread but yet overlooked feature of Arctic winter sea ice growth