Recent Environmental Changes in the Arctic: A Review

Numerous recent observations indicate that the Arctic is undergoing a significant change. In the last decade, the hydrography of the Arctic Ocean has shifted, and the atmospheric circulation has undergone a change from the lower stratosphere to the surface. Typically the eastern Arctic Ocean, on the European side of the Lomonosov Ridge, is dominated by water of Atlantic origin. A cold halocline of varying thickness overlies the warmer Atlantic water and isolates it from the sea ice and surface mixed layer. The western Arctic Ocean, on the North American side of the Lomonosov Ridge, is characterized by an added layer of water from the Pacific immediately below the surface mixed layer. Data collected during several cruises from 1991 to 1995 indicate that in the 1990s the boundary between these eastern and western halocline types shifted from a position roughly parallel to the Lomonosov Ridge to near alignment with the Alpha and Mendeleyev Ridges. The Atlantic Water temperature has also increased, and the cold halocline has become thinner. The change has resulted in increased surface salinity in the Makarov Basin. Recent results suggest that the change also includes decreased surface salinity and greater summer ice melt in the Beaufort Sea. Atmospheric pressure fields and ice drift data show that the whole patterns of atmospheric pressure and ice drift for the early 1990s were shifted counterclockwise 40°-60° from earlier patterns. The shift in atmospheric circulation seems related to the Arctic Oscillation in the Northern Hemisphere atmospheric pressure pattern. The changes in the ocean circulation, ice drift, air temperatures, and permafrost can be explained as responses to the Arctic Oscillation, as can changes in air temperatures over the Russian Arctic. De nombreuses observations effectuées récemment indiquent qu'un changement majeur est en train de se produire dans l'Arctique. Au cours des dix dernières années, l'hydrographie de l'océan Arctique s'est déplacée et la circulation atmosphérique a subi un changement, de la basse stratosphère à la surface. En général, l'océan Arctique oriental, du côté européen de la dorsale Lomonosov, est dominé par l'eau d'origine atlantique. Une halocline froide d'épaisseur variable est sus-jacente à l'eau atlantique plus chaude et l'isole de la glace marine et de la couche mixte de surface. L'océan Arctique occidental, du côté nord-américain de la dorsale Lomonosov, se caractérise par une couche supplémentaire d'eau du Pacifique située juste au-dessous de la couche mixte de surface. Les données recueillies au cours de plusieurs croisières de 1991 à 1995 indiquent que, dans les années 1990 la limite entre ces types d'haloclines de l'est et de l'ouest est passée d'une position plus ou moins parallèle à la dorsale Lomonosov, à un alignement presque parfait avec les dorsales Alpha et Mendeleyev. La température des eaux de l'Atlantique a également augmenté, et l'halocline froide s'est amincie. Ce changement a amené une augmentation de la salinité de surface dans le bassin de Makarov. De récents résultats suggèrent que le changement s'accompagne d'une diminution de la salinité de surface et d'une augmentation de la fonte estivale de la glace dans la mer de Beaufort. Les données barométriques et celles de la dérive des glaces montrent que tous les schémas de pression atmosphérique et de dérive des glaces pour les premières années de 1990 se sont déplacés de 40 à 60° par rapport aux précédents. Le déplacement dans la circulation atmosphérique semble lié à l'oscillation arctique dans le schéma de pression atmosphérique de l'hémisphère Nord. Les changements dans la circulation océanique, la dérive des glaces, la température de l'air et le pergélisol peuvent s'expliquer comme une réponse à l'oscillation arctique, tout comme les changements dans la température de l'air au-dessus de l'Arctique russe.

High incidence of acute full-thickness rotator cuff tears. A population-based prospective study in a Swedish Community.

Background and purpose - Epidemiological studies of full-thickness rotator cuff tears (FTRCTs) have mainly investigated degenerative lesions. We estimated the population-based incidence of acute FTRCT using a new diagnostic model. Patients and methods - During the period November 2010 through October 2012, we prospectively studied all patients aged 18-75 years with acute onset of pain after shoulder trauma, with limited active abduction, and with normal conventional radiographs. 259 consecutive patients met these inclusion criteria. The patients had a median age of 51 (18-75) years. 65% were males. The patients were divided into 3 groups according to the clinical findings: group I, suspected FTRCT; group II, other specific diagnoses; and group III, sprain. Semi-acute MRI was performed in all patients in group I and in patients in group III who did not recover functionally. Results - We identified 60 patients with FTRCTs. The estimated annual incidence of MRI-verified acute FTRCT was 16 (95% CI: 11-23) per 105 inhabitants for the population aged 18-75 years and 25 (CI: 18-36) per 105 inhabitants for the population aged 40-75 years. The prevalence of acute FTRCT in the study group was 60/259 (23%, CI: 18-28). The tears were usually large and affected more than 1 tendon in 36 of these 60 patients. The subscapularis was involved in 38 of the 60 patients. Interpretation - Acute FTRCTs are common shoulder injuries, especially in men. They are usually large and often involve the subscapularis tendon

Den språklige faktor : pedagogisk-psykologisk utredning av barn med minoritetsspråklig bakgrunn

The dissertation deals with school psychology assessment of minority language children in a typical sample of Norwegian school psychology services, in a three-phase design with an embedded intervention, where statements are evaluated before and after professional development, and for long term effect after a two year latency period. Internationally there are few studies of assessment practices aimed at language minority students, and no one study points to adequate national practices in any country. Typically, minority language students are assessed predominantly as though they were majority language students, without sufficient account being taken of their social, cultural and linguistic characteristics, and without exploiting the existing knowledge base on bilingualism, education and special education. The two first chapters draw a line between language as an evolved speciesspecific biological entity, an abstract construct not easily studied, and bilingualism as a basic fact of social life, a vehicle of communication. Contrasting theoretical positions are discussed. The dissertation is based on Cummins' theory that learning outcomes for minority language students are a resultant of causal social, pedagogical and individual factors mediated through a language factor. Dominant in the fields of bilingual education and special education and well corroborated empirically, the theory is insufficiently taken into account in national school systems and school psychology services. The theory and the critique it has been subjected to, are discussed in chapters 3 to 6. After a short introduction to various educational models for language minority students (chapter 7), arguing for strong bilingual programs, empirical research on assessment practices is presented (chapter 8), documenting the need for more and better research along the lines of this project. Especially, there is a need for longitudinal studies, studies of actual practices as opposed to reported practices, studies incorporating professional development, and studies integrating quantitative, qualitative and discourse analyses by way of triangulation. The present study seems to be the first of its kind in these respects, taken together. A section on the Norwegian school system (chapters 9 and 10) critically analyzes the historical and conceptual bases of Norwegian education and special education. It is argued that the conceptual basis of Norwegian schooling – inclusion and special needs education for all – is weakly founded theoretically, poorly implemented, and has led to – and necessarily must lead to – high rates of school-generated learning problems, affecting minority students not least. It is argued that the professional tension between special education and general education, which arose with the introduction of inclusion and special needs education for all in 1976, could be settled by adopting an integrated individual and systems perspective on special education. It is further argued that school psychology services and special education cannot be blamed for high rates of school-generated problems in the general student population, and should not - as they have been of late - be called upon to help schools solve problems for which general education exclusively has the mandate and the competence, namely the inclusion of, adaption to, and teaching of ordinary students. An analysis of the mandatory guidelines for the instruction of minority students in schools (chapters 11 and 12) concludes that the recommendations (e.g. to develop minority students' bilingualism) were laudable but poorly implemented by 1997. Since 1997, the goal of minority student bilingualism has been abandoned and replaced by a theoretically unjustified and poorly implemented model of linguistic compensation (mother tongue teaching on a pull-out basis, second language teaching – comparable to ESL – and first language assistance in class), which has no documented effect on learning outcomes in Norway. Mandatory guidelines and evaluations of professional practices of national school psychology services are critically analyzed (chapters 13 and 14), assuming that the effects of the services’ professional practices toward minority students are largely unknown, in spite of some state and scientific pretensions to the contrary. The present study aims at contributing to the closure of this knowledge gap. In a section on methodological theory (chapters 15 to 17) a realistic, practicable and consensus-orientated model of minority student special needs assessment is first presented, derived from legal guidelines, current school psychology practices and the scientific knowledge base presented in preceding chapters, the three constraining factors delimiting and delineating the field of possible improvement. This realistic assessment tool is used normatively throughout the project as the yard-stick of non-discriminatory assessment. Next, in chapter 16, the typical problems dealt with in school psychology statements are summarized, organized hierarchically to fit study design (i.e. possible language linkage). Last, in chapter 17, the socratic interview is introduced, the chosen tool for interviewing participating school psychologists. Primary data in this project are 40 interviews conducted in 2001, and 94 statements written in phase 1 to 3 between 1997 and 2004. Data are analyzed by triangulation, quantitatively through an operationalized check-list based on the proposed yard-stick, qualitatively by an expert panel, and through discourse analysis. Simple statistical tools of frequencies and correlations are used for the analyses. In support of data analysis a few additional tools have been developed (participants’ evaluation of professional development and of project participation, a measure discerning possibly effort-related from knowledge-related improvement, new statement conclusions and suggestions as an expression of new knowledge, and a control study conducted in 2010 (60 pristine statements analyzed quantitatively), suggesting that main findings are not dated). The embedded intervention was a small two day program of professional development, each day (interspersed by a month) consisting of a lengthy lecture and some group supervision of ongoing statementing. The rationale of the intervention was to find out whether substantial change can be effected through a minimal but well directed program, realistic on a national scale. Methodological considerations are presented in chapter 18. The interview with 40 participants (chapters 19 to 25) reveal limited competence for work with the target group and poor knowledge of non-discriminatory assessment, legal guidelines, and established scientific insights in the field of bilingual special education, e.g. the importance of the language factor. Participants’ actual professional practices are presented in chapters 26 to 30. Statements written before intervention are not compliant with non-discriminatory assessment, in that minority students predominantly are assessed as though they were majority students, a finding consistent with existing international research. A discrepancy is showed between reported and actual practices, a problem often alluded to, but not sufficiently studied. No relation can be demonstrated between practices and factors that ought to predict them, i.e. professional preparation and experience. Substancial improvements, attributable to the intervention, are documented in phase 2. Practices improve with added knowledge. In phase 3, two years after intervention, practices are, expectedly, variable. Some participants show further improvement, possibly having taken a special interest from their participation, some retain the gain, and some return to square one, showing few or no signs of improved understanding. It is argued that improvements could easily have been sustained with a minimum of supervised work over some time. Results are discussed in chapter 31 and found valid and reliable. Findings and generalizability are discussed in chapter 32. The control study (2010) suggests that findings are not dated. It is concluded that official guidelines for the schooling and special education of minority students are theoretically unwarranted and should be changed. It is argued that documented limitations in the professional preparation of school psychologists should lead to curricular change in universities, along the lines of ”best practices” recommendations suggested in this dissertation. The method and theoretical foundations employed in this project should be of value for professional development, for research, and for administrative and scientific evaluation and monitoring of current practices. It is strongly underscored that the revealed shortcomings result from structural and political factors and are not attributable to individual lack of professionalism. School psychology does have a problem, but this problem is soluble through an available and cost-efficient intervention. The viability of such professional improvements in national services has not previously been demonstrated in the professional literature

The large‐scale freshwater cycle of the Arctic

This paper synthesizes our understanding of the Arctic\u27s large‐scale freshwater cycle. It combines terrestrial and oceanic observations with insights gained from the ERA‐40 reanalysis and land surface and ice‐ocean models. Annual mean freshwater input to the Arctic Ocean is dominated by river discharge (38%), inflow through Bering Strait (30%), and net precipitation (24%). Total freshwater export from the Arctic Ocean to the North Atlantic is dominated by transports through the Canadian Arctic Archipelago (35%) and via Fram Strait as liquid (26%) and sea ice (25%). All terms are computed relative to a reference salinity of 34.8. Compared to earlier estimates, our budget features larger import of freshwater through Bering Strait and larger liquid phase export through Fram Strait. While there is no reason to expect a steady state, error analysis indicates that the difference between annual mean oceanic inflows and outflows (∼8% of the total inflow) is indistinguishable from zero. Freshwater in the Arctic Ocean has a mean residence time of about a decade. This is understood in that annual freshwater input, while large (∼8500 km3), is an order of magnitude smaller than oceanic freshwater storage of ∼84,000 km3. Freshwater in the atmosphere, as water vapor, has a residence time of about a week. Seasonality in Arctic Ocean freshwater storage is nevertheless highly uncertain, reflecting both sparse hydrographic data and insufficient information on sea ice volume. Uncertainties mask seasonal storage changes forced by freshwater fluxes. Of flux terms with sufficient data for analysis, Fram Strait ice outflow shows the largest interannual variability

Distributions of nuclear fuel-reprocessing tracers in the Arctic Ocean: Indications of Russian river influence

Radionuclide sampling in 1986 and 1993 in the Canada Basin, and in 1993 in the Amundsen Basin and on the adjacent Laptev shelf, provides new insights into the origin, timing, pathways, and mechanisms for dispersal of non-fallout radioactive tracers in the Arctic Ocean. First, samples from the Beaufort Sea shelf, slope, and adjacent basin show a four-fold increase in 129I concentrations from 1986 to 1993. Second, anthropogenic non-fallout radionuclide concentrations in the Beaufort Sea increase with proximity to slope boundary currents. Third, there is evidence for riverine contributions of anthropogenic radionuclides to surface waters of the Amundsen Basin and the Laptev continental shelf. This evidence includes high surface water burdens of 237Np and 129I, with the maximum in anthropogenic 129I found in the least saline and most 18O-depleted waters, consistent with an origin in high-latitude runoff. Additionally, the 237Np/129I atom ratios in the Laptev Sea and Amundsen Basin in 1993 were significantly lower than observed elsewhere in the Arctic Ocean and can be reasonably explained by 129I added during transit of the Russian shelves. The 240Pu/239Pu ratios in the water column were mostly near 0.18, consistent both with stratospheric bomb fallout and with the discharged-weighted mean Sellafield ratio during 1966-1985. In the least saline water samples collected at the most shallow Laptev shelf station, however, the Pu ratios were lower, consistent with a non-European nuclear fuel reprocessing source. There are clear secondary maxima in 237Np and 129I near 1000 m in the Amundsen Basin, likely associated with the Barents Sea branch of Atlantic water. Finally, the 129I/salinity and 129I/δ18O relationships in the Amundsen and Canada Basins at middepths are indistinguishable, suggesting effective horizontal dispersion

Trajectory shifts in the Arctic and Subarctic freshwater cycle

Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of American Association for the Advancement of Science for personal use, not for redistribution. The definitive version was published in Science 313 (2006): 1061-1066, doi:10.1126/science.1122593.Manifold changes in the freshwater cycle of high-latitude lands and oceans have been reported in the past few years. A synthesis of these changes in sources of freshwater and in ocean freshwater storage illustrates the complementary and synoptic temporal pattern and magnitude of these changes over the past 50 years. Increasing river discharge anomalies and excess net precipitation on the ocean contributed ~20,000 km3 of fresh water to the Arctic and high latitude North Atlantic oceans from lows in the 1960s to highs in the 1990s. Sea ice attrition provided another ~15,000 km3, and glacial melt added ~2000 km3. The sum of anomalous inputs from these freshwater sources matched the amount and rate at which fresh water accumulated in the North Atlantic during much of the period from 1965 through 1995. The changes in freshwater inputs and ocean storage occurred in conjunction with the amplifying North Atlantic Oscillation and rising air temperatures. Fresh water may now be accumulating in the Arctic Ocean and will likely be exported southward if and when the North Atlantic Oscillation enters into a new high phase.Funding was provided by NSF (grants OPP-0229302, OPP- 0436118, OPP-0327664, OPP-0352754, OPP-0519840, OCE- 0326778), ONR (grant N00014-02-1-0305) and NASA (grant IDS-03-0000-0145)

The St. Lawrence polynya and the Bering shelf circulation : new observations and a model comparison

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C09023, doi:10.1029/2005JC003268.Using 14 year-long instrumented moorings deployed south of St. Lawrence Island, along with oceanographic drifters, we investigate the circulation over the central Bering shelf and the role of polynyas in forming and disseminating saline waters over the shelf. We focus also on evaluating the Gawarkiewicz and Chapman [1995] model of eddy production within coastal polynyas. Principal results include: 1) The northern central shelf near-surface waters exhibit westward flow carrying low-salinity waters from the Alaskan coast in fall and early winter, with consequences for water mass formation and biological production. 2) Within the St. Lawrence polynya, the freshening effect of winter advection is about half as large as the salting effect of surface brine flux resulting from freezing. 3) Brine production over the Bering shelf occurs primarily offshore, rather than within coastal polynyas, even though ice production per unit area is much larger within the polynyas. 4) We find little evidence for the geostrophic flow adjustment predicted by recent polynya models. 5) In contrast to the theoretical prediction that dense water from the polynya is carried offshore by eddies, we find negligible cross-shelf eddy density fluxes within and surrounding the polynya and very low levels of eddy energy that decreased from fall to winter, even though dense water accumulated within the polynya and large cross-shore density gradients developed. 6) It is possible that dense polynya water was advected downstream of our array before appreciable eddy fluxes materialized.This work was supported by National Science Foundation grant OCE9730697 to the University of Alaska and grant OCE9730823 to the University of Washington. S. M. acknowledges the support of the National Science Foundation under OCE9811097 and of NASA under grant NNG04GM69G. The University of Hamburg contributions were funded by the Bundesminister für Bildung und Wissenschaft. Funding for the drifter deployment was made possible by the North Pacific Research Board, grant NPMRI T2130. Manuscript preparation was additionally supported by Office of Naval Research grants N00014-99-1-0345 and N00014-02-1-0305 to the University of Washington

Coupled wind-forced controls of the Bering–Chukchi shelf circulation and the Bering Strait throughflow: Ekman transport, continental shelf waves, and variations of the Pacific–Arctic sea surface height gradient

AbstractWe develop a conceptual model of the closely co-dependent Bering shelf, Bering Strait, and Chukchi shelf circulation fields by evaluating the effects of wind stress over the North Pacific and western Arctic using atmospheric reanalyses, current meter observations, satellite-based sea surface height (SSH) measurements, hydrographic profiles, and numerical model integrations. This conceptual model suggests Bering Strait transport anomalies are primarily set by the longitudinal location of the Aleutian Low, which drives oppositely signed anomalies at synoptic and annual time scales. Synoptic time scale variations in shelf currents result from local wind forcing and remotely generated continental shelf waves, whereas annual variations are driven by basin scale adjustments to wind stress that alter the magnitude of the along-strait (meridional) pressure gradient. In particular, we show that storms centered over the Bering Sea excite continental shelf waves on the eastern Bering shelf that carry northward velocity anomalies northward through Bering Strait and along the Chukchi coast. The integrated effect of these storms tends to decrease the northward Bering Strait transport at annual to decadal time scales by imposing cyclonic wind stress curl over the Aleutian Basin and the Western Subarctic Gyre. Ekman suction then increases the water column density through isopycnal uplift, thereby decreasing the dynamic height, sea surface height, and along-strait pressure gradient. Storms displaced eastward over the Gulf of Alaska generate an opposite set of Bering shelf and Aleutian Basin responses. While Ekman pumping controls Canada Basin dynamic heights (Proshutinsky et al., 2002), we do not find evidence for a strong relation between Beaufort Gyre sea surface height variations and the annually averaged Bering Strait throughflow. Over the western Chukchi and East Siberian seas easterly winds promote coastal divergence, which also increases the along-strait pressure head, as well as generates shelf waves that impinge upon Bering Strait from the northwest

Isolation of Mycobacterium avium Subspecies paratuberculosis Reactive CD4 T Cells from Intestinal Biopsies of Crohn's Disease Patients

BACKGROUND:Crohn's disease (CD) is a chronic granulomatous inflammation of the intestine. The etiology is unknown, but an excessive immune response to bacteria in genetically susceptible individuals is probably involved. The response is characterized by a strong Th1/Th17 response, but the relative importance of the various bacteria is not known. METHODOLOGY/PRINCIPAL FINDINGS:In an attempt to address this issue, we made T-cell lines from intestinal biopsies of patients with CD (n = 11), ulcerative colitis (UC) (n = 13) and controls (n = 10). The T-cell lines were tested for responses to various bacteria. A majority of the CD patients with active disease had a dominant response to Mycobacterium avium subspecies paratuberculosis (MAP). The T cells from CD patients also showed higher proliferation in response to MAP compared to UC patients (p<0.025). MAP reactive CD4 T-cell clones (n = 28) were isolated from four CD patients. The T-cell clones produced IL-17 and/or IFN-gamma, while minimal amounts of IL-4 were detected. To further characterize the specificity, the responses to antigen preparations from different mycobacterial species were tested. One T-cell clone responded only to MAP and the very closely related M. avium subspecies avium (MAA) while another responded to MAP, MAA and Mycobacterium intracellulare. A more broadly reactive T-cell clone reacted to MAP1508 which belongs to the esx protein family. CONCLUSIONS/SIGNIFICANCE:The presence of MAP reactive T cells with a Th1 or Th1/Th17 phenotype may suggest a possible role of mycobacteria in the inflammation seen in CD. The isolation of intestinal T cells followed by characterization of their specificity is a valuable tool to study the relative importance of different bacteria in CD