SYMMETRIC SPACES WITH DISSECTING INVOLUTIONS

An involutive diffeomorphism σ of a connected smooth manifold M is called dissecting if the complement of its fixed point set is not connected. Dissecting involutions on a complete Riemannian manifold are closely related to constructive quantum field theory through the work of Dimock and Jaffe/Ritter on the construction of reflection positive Hilbert spaces. In this article we classify all pairs (M, σ), where M is an irreducible connected symmetric space, not necessarily Riemannian, and σ is a dissecting involutive automorphism. In particular, we show that the only irreducible, connected and simply connected Riemannian symmetric spaces with dissecting isometric involutions are Sn and ℍn, where the corresponding fixed point spaces are Sn−1 and ℍn − 1, respectively

Downslope windstorm in Iceland ? WRF/MM5 model comparison

International audienceA severe windstorm downstream of Mnt. Öræfajökull in Southeast Iceland is simulated on a grid of 1 km horizontal resolution by using the PSU/NCAR MM5 model and the Advanced Research WRF model. Both models are run with a new, two equation planetary boundary layer (PBL) scheme as well as the ETA/MYJ PBL schemes. The storm is also simulated using six different micro-physics schemes in combination with the MYJ PBL scheme in WRF. Output from a 3 km MM5 domain simulation is used to initialise and drive both the 1 km MM5 and WRF simulations. Both models capture gravity-wave breaking over Mnt. Öræfajökull, while the vertical structure of the lee wave differs between the two models and the PBL schemes. The WRF simulated downslope winds, using the MYJ PBL scheme, are in good agreement with the strength of the observed downslope windstorm, whilst using the new two equation scheme surface winds are considerably less than observed winds. The MM5 simulated surface winds, with the new two equation model, are in better agreement with observations than when using the ETA scheme. Micro-physics processes are shown to play an important role in the formation of downslope windstorms and lifting of the upslope isotherm layer from mountain height to about 1.3 times the mountain height leads to a significant increase in the downslope windstorm

Brain abscess - overview.

Heilaígerð er lífshættulegur sjúkdómur sem krefst skjótrar greiningar og meðferðar. Á undanförnum áratugum hafa horfurnar batnað til muna og dánartíðni lækkað úr 50% í 10%. Þessi þróun endurspeglar bætta myndgreiningu, skurðtækni og sýklalyfjameðferð. Ígerð í heila er staðbundin sýking. Fyrst verður til afmörkuð heilabólga sem þróast á tveimur vikum yfir í dauðan vef og samansafn af greftri sem afmarkast af vel blóðnærðu hýði. Sýkingin sem veldur ígerðinni getur borist inn í heilavefinn eftir þremur ólíkum leiðum. Í fyrsta lagi bein dreifing sýkingar frá afholum nefs, tönnum, miðeyra eða stikilbeini. Í öðru lagi blóðborin orsök þar sem sýking hefur dreift sér frá fjarlægum stað til heilans með tilflutningi blóðs. Í þriðja lagi í kjölfar heilaaðgerðar eða höfuðáverka þar sem rof verður á heilakúpunni. Allt að 30% heilaígerða eru af óþekktum orsökum þar sem upprunalegur sýkingarstaður finnst ekki þrátt fyrir ítarlega leit. Algengustu einkennin eru versnandi höfuðverkur og staðbundin taugaeinkenni. Flog koma fram hjá 25-50%. Meðferð heilaígerða er fólgin í skurðaðgerð og sýklalyfjameðferð.Brain abscess is a life threatening illness, demanding rapid diagnosis and treatment. Its development requires seeding of an organism into the brain parenchyma, often in an area of damaged brain tissue or in a region with poor microcirculation. The lesion evolves from a cerebritis stage to capsule formation. Brain abscesses can be caused by contiguous or haematogenous spread of an infection, or by head trauma/ neurosurgical procedure. The most common presentation is that of headache and vomiting due to raised intracranial pressure. Seizures have been reported in up to 50% of cases. Focal neurological deficits may be present, depending on the location of the lesion. Treatment of a brain abscess involves aspiration or excision, along with parenteral antibiotic therapy. The outcome has improved dramatically in the last decades due to improvement in diagnostic techniques, neurosurgery, and broad-spectrum antibiotics. The authors provide an overview of the pathogenesis, diagnosis and management of brain abscesses

Repair of distal biceps brachii tendon ruptures: long term retrospective follow-up for two-incision technique

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenINTRODUCTION: Rupture of the distal tendon of the biceps muscle is a rare injury. If unrepaired the patient will be left with weakness of supination of the arm and flexion in the elbow. Long term results for the 2-incision approach for tendon reinsertion are few but in this study we describe the long term, clinical, functional, and subjective results of surgical repair using the 2-incision method described by Boyd and Anderson. MATERIAL AND METHODS: All patients who were operated at FSA hospital during the years 1986-2000 because of rupture of the distal tendon of the biceps muscle were asked to participate in the study. Twelve of 16 patients accepted and answered the DASH questionnaire. Strength was tested with handheld dynamometer and ROM where measured. Radiograph was taken of the affected arm. RESULTS: From 1986 through 2006 we operated on 16 patients because of rupture of the distal biceps tendon, one female and 15 male. Mean age at the time of rupture was 46 years (24-53).The average follow up were seven years (1-17). Ten of 12 patients were operated within two weeks from the injuries. No difference in strength was found between operated and non-operated arms. Late repair was associated with high DASH score and poor subjective results. Six patients developed heterotopic ossification but none of them developed radioulnar synostosis. One reoperation because entrapment of the median nerve was done. CONCLUSIONS: Despite heterotopic ossification and a small ROM deficit the Boyd and Anderson technique for repair of distal biceps ruptures yields good long term results in a low volume rural hospital. Early diagnosis and tendon reinsertion is of great importance to avoid persistent anterior elbow pain and poor subjective results.Inngangur: Slit á fjærsin tvíhöfðavöðva upphandleggs (biceps brachi) er sjaldgæfur áverki og árangur af aðgerðum því lítt þekktur. Lýst er árangri af aðgerðum þar sem fjærsin tvíhöfðavöðva upphandleggs er endurfest með aðgerð kenndri við Boyd og Anderson. Þá eru notaðar tvær leiðir til að komast að sininni og endurfesta. Efniviður og aðferðir: Þeir sem höfðu slitið fjærsin tvíhöfðavöðva upphandleggs á árunum 1986-2006 og gengist undir aðgerð á Sjúkrahúsi Akureyrar voru beðnir að taka þátt í rannsókninni sem fólst í líkamsskoðun, hreyfiferils- og styrktarmælingum, svörun spurningalista og rö ntgenmyndatöku af olnboga og framhandlegg. Niðurstöður: Sextán manns (15 karlar, 1 kona), meðalaldur 46 ár (24-53) gengust undir aðgerð þar sem sinin var endurfest með aðferð Boyds og Andersons. Tólf sjúklingar samþykktu að taka þátt í rannsókninni, allt rétthendir karlmenn. Tíu af 12 sjúklingum gengust undir aðgerðina innan tveggja vikna frá áverkanum (0-80 dagar). Allar sinarnar greru eftir að þær voru endurfestar. Munur var ekki tölfræðilega marktækur á styrk í aðgerðararmi og þeim armi sem ekki var gerð aðgerð á. Meðal DASH-stigun var 11,7 sem telst lágt. Helmingur sjúklinga hafði merki um beinnýmyndun í mjúkvefjum. Ályktun: Þrátt fyrir beinnýmyndun í mjúkvefjum og væga hreyfiskerðingu í aðgerðararminum virðist langtímaárangur aðgerðartækni þeirra Boyds og Andersons góður. Rétt greining og aðgerð fljótlega eftir áverka virðist vera lykilatriði til þess að sjúklingum farnist vel

Defects in SiO2 as the possible origin of near interface traps in the SiC∕SiO2 system: A systematic theoretical study

A systematic study of the level positions of intrinsic and carbon defects in SiO2 is presented, based on density functional calculations with a hybrid functional in an alpha-quartz supercell. The results are analyzed from the point of view of the near interface traps (NIT), observed in both SiC/SiO2 and Si/SiO2 systems, and assumed to have their origins in the oxide. It is shown that the vacancies and the oxygen interstitial can be excluded as the origin of such NIT, while the silicon interstitial and carbon dimers give rise to gap levels in the energy range inferred from experiments. The properties of these defects are discussed in light of the knowledge about the SiC/SiO2 interface

Spontaneous subarachnoid haemorrhage : review

Spontaneous subarachnoid hemorrhage is a bleeding in to the subarachnoid space without trauma. Aneurysms are the underlying cause in 80% of the cases. Among other causes are: arteriovenous malformations, anticoagulation, vasculitis or brain tumor. Spontaneous subarachnoid hemorrhage is a serious disease, where up to half of the patients die. Of those who survive, only half return to work and many have a reduced quality of life. To prevent rebleeding the aneurysm is closed either with endovascular coiling or neurosurgical clipping.Sjálfsprottin innanskúmsblæðing er blæðing inn í innanskúmshol án þess að um áverka sé að ræða. Æðagúlar eru orsökin í 80% tilfella. Aðrar ástæður eru æðamissmíð, blóðþynningarmeðferð, æðabólga og æxli í heilavef. Sjálfsprottin innanskúmsblæðing er algengasta ástæða heilablóðfalls hjá ungu fólki. Nálægt helmingur sjúklinga deyr af völdum sjúkdómsins. Af þeim sem lifa af kemst aðeins helmingur í fulla vinnu aftur og margir búa við skert lífsgæði. Í endurblæðingu felst mesta bráðahættan. Því beinast fyrstu viðbrögð að lokun æðagúlsins, annaðhvort með innanæðahnoðrun með platínuþráðum, eða klemma er sett á æðagúlinn með taugaskurðaðgerð

Spontaneus intracerebral haemhorrhage--review

Efst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinnSjálfsprottin heilavefsblæðing (spontaneous intracerebral hemorrhage) er blæðing inn í heilavefinn án þess að um ytri áverka sé að ræða. Milli 10 og 15% allra heilablóðfalla stafa af henni. Árlega veikjast um 30-50 einstaklingar af heilavefsblæðingu á Íslandi. Dánartíðnin er afar há (30 daga dánartíðni er 25-50%). Háþrýstingur er algengasta orsökin en ávallt ber að hafa í huga sértækari orsakir, sér í lagi hjá yngra fólki. Ekki hefur verið sýnt fram á árangur af skurðaðgerðum nema í sérstökum tilvikum eins og stórum blæðingum í litlaheila. Hins vegar er afar mikilvægt að sjúklingar með heilavefsblæðingu séu vistaðir á gjörgæsludeildum eða heilablóðfallseiningum þar sem viðhaft er nákvæmt eftirlit með vökustigi, taugaeinkennum, blóðþrýstingi og vökvabúskap. ---------------------------------- Spontaneous intracerebral hemorrhage occurs when a blood vessel within the brain parenchyma ruptures without a near related trauma. It is the second most common form of stroke, accounting for approximately 10% to 15% of new strokes. The 30 day mortality is very high (25-50%). Hypertension is the most common cause. Unfortunately, surgery has not proven to be helpful except in certain exceptions such as in large cerebellar hemorrhage. Nonetheless, it is very important that patients with ICH are admitted to an intensive care or a stroke unit with close surveillance of consciousness, focal neurologic symptoms, blood pressure and fluid balance

The Theistareykir Geothermal Field, NE Iceland. Isotopic Characteristics and Origin of Circulating Fluids

AbstractThe Theistareykir high temperature field in NE Iceland seems to be complex in terms of both inflow and structure, as reflected in the division of the area into several subfields. Oxygen and hydrogen isotopes in water and steam condensate from wells are reported. Some differences can be seen between the Theistareykir well fields, but the recharge is in all cases non-local in origin. The isotopic composition of some of the thermal waters is anomalously depleted in 2H, by about 35‰, compared to precipitation anywhere in Iceland today. The isotopes therefore suggest that the thermal water contains a component of past precipitation under a colder climate. The oxygen shift due to water-rock interaction is up to 6.5 ‰. The isotopic signature of the Theistareykir thermal water is compared to that from nearby low temperature fields within the westernmost part of the Northern Neovolcanic Zone

Aircraft-based observations and high-resolution simulations of an Icelandic dust storm

The first aircraft-based observations of an Icelandic dust storm are presented. The measurements were carried out over the ocean near Iceland's south coast in February 2007. This dust event occurred in conjunction with an easterly barrier jet of more than 30 m s<sup>−1</sup>. The aircraft measurements show high particle mass mixing ratios in an area of low wind speeds in the wake of Iceland near the coast, decreasing abruptly towards the jet. Simulations from the Weather Research and Forecasting Model coupled with Chemistry (WRF/Chem) indicate that the measured high mass mixing ratios and observed low visibility inside the wake are due to dust transported from Icelandic sand fields towards the ocean. This is confirmed by meteorological station data. Glacial outwash terrains located near the Mýrdalsjökull glacier are among simulated dust sources. Sea salt aerosols produced by the impact of strong winds on the ocean surface started to dominate as the aircraft flew away from Iceland into the jet. The present results support recent studies which suggest that Icelandic deserts should be considered as important dust sources in global and regional climate models

Interpolation Theorems for Self-adjoint Operators

We prove a complex and a real interpolation theorems on Besov spaces and Triebel-Lizorkin spaces associated with a selfadjoint operator $L$, without assuming the gradient estimate for its spectral kernel. The result applies to the cases where $L$ is a uniformly elliptic operator or a Schr\"odinger operator with electro-magnetic potential.Comment: 8 pages. Submitte