Local Spectral Weight of a Luttinger Liquid: Effects from Edges and Impurities

We calculate the finite-temperature local spectral weight (LSW) of a Luttinger liquid with an "open" (hard wall) boundary. Close to the boundary the LSW exhibits characteristic oscillations indicative of spin-charge separation. The line shape of the LSW is also found to have a Fano-like asymmetry, a feature originating from the interplay between electron-electron interaction and scattering off the boundary. Our results can be used to predict how edges and impurities influence scanning tunneling microscopy (STM) of one-dimensional electron systems at low temperatures and voltage bias. Applications to STM on single-walled carbon nanotubes are discussed.Comment: 15 pages, 10 figues, The latest version in pdf format is available at http://www.physik.uni-kl.de/eggert/papers/LSW-LL.pd

The effect of dietary fish oil on bacterial growth in vivo

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: Epidemiological studies have indicated that high intake of w-3 fatty acids influence various diseases such as cardiovascular diseases and autoimmune disorders. These fatty acids are essential in the diet since the body can not form them de novo. Fish oil is rich in w-3 fatty acids but the w-3 content of vegetable oil is low. The research group has shown increased survival of mice fed cod liver oil enriched diet versus mice fed corn oil enriched diet when infected with Klebsiella pneumoniae intramuscularly. In the present study we investigated the effect of dietary fish oil on bacterial growth in vivo. Material and methods: Mice were fed fish oil enriched diet and a control group was fed corn oil enriched diet for six weeks and then the mice were infected with Klebsiella pneumoniae intramuscularly. The mice were sacrificed at various time intervals and bacteria were counted in blood and in the infected muscle. Results: The bacteria count in blood and tissue was not significantly different between the two groups although a trend was noted towards more growth in the control group. Conclusions: We conclude that fish oil does not significantly affect bacterial growth in vivo. Hopefully, future research will reveal the pathophysiological effect of fish oil.Tilgangur: Faraldsfræðilegar rannsóknir benda til að mikil neysla w-3 fitusýra hafi áhrif á ýmsa sjúkdóma svo sem hjarta- og æðasjúkdóma og sjálfnæmissjúkdóma. Líkaminn getur ekki nýmyndað w-3 fitusýrur, og því er nauðsynlegt að fá þær úr fæðunni. Lýsi er mjög ríkt af slíkum fitusýrum, en jurtaolíur aftur á móti ekki. Rannsóknarhópurinn hefur sýnt fram á aukna lifun músa sem fengið höfðu lýsisbætt fæði samanborið við mýs sem fengu kornolíubætt fæði og voru sýktar með Klebsiella pneumoniae í vöðva. Í þessari rannsókn var kannað, hvort þau áhrif væru vegna áhrifa lýsis á bakteríuvöxt in vivo. Efniviður og aðferðir: Mýs voru aldar á lýsisbættu fæði eða kornolíubættu fæði til viðmiðunar í sex vikur og þá sýktar með Klebsiella pneumoniae í vöðva. Mýsnar voru aflífaðar á mismunandi tímapunktum og var fjöldi baktería í blóði og frá sýkingarstað talinn. Niðurstöður: Ekki var marktækur munur á bakteríufjöldanum í hópunum á mismunandi tímapunktum, hvorki í blóði né á sýkingarstað, þó var tilhneiging til meiri vaxtar í kornolíuhópnum. Ályktanir: Lýsi virðist ekki hafa marktæk áhrif á bakteríuvöxt in vivo. Frekari rannsóknir munu vonandi leiða nánar í ljós hver áhrif lýsisins eru

Effect of dietary fish-oil on survival of experimental animals after infection with Streptococcus pneumoniae or Klebsiella pneumoniae

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: Dietary fish-oil has beneficial effect in infections and in autoimmune disorders. This effect is thought to be associated with alterations in the immune system. The Gram negative organism Klebsiella pneumoniae has been used as an infective agent in most studies investigating the effect of dietary fish-oil on infection. The immune response against Gram positive bacteria is somewhat different to the response to Gram negative oeganisms. Moreover, the Gram positive bacteria Streptococcus pneumoniae is a very common pathogen, particularly in children. To investigate whether dietary fish-oil has different effect in infections by Gram positive or Gram negative bacteria, we studied the survival of mice fed with fish-oil or corn-oil supplemented diets and infected in the lungs with either Klebsiella pneumoniae or Streptococcus pneumoniae. Materials and methods: 120 NMRI mice were divided into four groups and fed diets supplemented with fish-oil (two groups, 30 mice in each group) or corn-oil (two groups, 30 mice in each group). After six weeks, the mice were infected with Klebsiella pneumoniae (fish-oil group and corn-oil group) or with Streptococcus pneumoniae serotype 3 (fish-oil group and corn-oil group). The survival was monitored. The experiment was performed twice. Results: The survival of the mice infected with Klebsiella pneumoniae was significantly better in the groups receiving the fish-oil enriched diet as compared to the groups fed the corn-oil enriched diet (p=0.0001 and 0.0013). There was no difference in the survival of mice infected with Streptococcus pneumoniae serotype 3, receiving the fish-oil or corn-oil enriched diets (p=0.74 and p=0.15). Conclusions: These results indicate that dietary fish-oil has beneficial effect on survival of mice after experimental infection with the Gram negative bacteria Klebsiella pneumoniae but not on experimental infections with the Gram positive bacteria Streptococcus pneumoniae serotype 3.Markmið: Áhrif lýsisneyslu á lifun eftir sýkingar og á sjálfnæmissjúkdóma hefur verið staðfest af ýmsum rannsóknarhópum. Talið er að áhrifin megi rekja til breytinga á ónæmissvari líkamans. Flestar rannsóknanna hafa verið gerðar með Gram neikvæðu bakteríunni Klebsiella pneumoniae. Ónæmissvarið gegn Gram jákvæðum bakteríum er nokkuð frábrugðið svari gegn Gram neikvæðum bakteríum. Þá er Gram jákvæða bakterían Streptococcus pneumoniae mjög algengur sýkingavaldur, einkum í börnum. Til að kanna hvort verndandi áhrif lýsisneyslu séu mismunandi eftir því hvort sýkt er með Gram jákvæðum eða Gram neikvæðum bakteríum rannsökuðum við áhrif lýsisríks fæðis á lifun músa eftir sýkingar með Klebsiella pneumoniae eða Streptococcus pneumoniae. Efniviður og aðferðir: 120 NMRI músum var skipt í fjóra hópa og voru aldar á fæði bættu með lýsi (tveir hópar, 30 mýs í hvorum hópi) eða á fæði bættu með kornolíu (tveir hópar, 30 mýs í hvorum hópi). Eftir sex vikur voru mýsnar sýktar með Klebsiella pneumoniae (lýsishópur og kornolíuhópur) eða með Streptococcus pneumoniae hjúpgerð 3 (lýsishópur og kornolíuhópur). Fylgst var með lifun músanna. Tilraunin var síðan endurtekin á sama hátt. Niðurstöður: Lifun músa sem sýktar voru með Klebsiella pneumoniae var marktækt betri hjá hópunum sem fengu lýsisríkt fæði samanborið við hópana sem fengu kornolíubætt fæði (p=0,0001 og 0,0013). Ekki var tölfræðilega marktækur munur á lifun músa sem sýktar voru með Streptococcus pneumoniae hjúpgerð 3 hvort heldur þær fengu lýsisríkt eða kornolíuríkt fæði (p=0,74 og p=0,15). Ályktanir: Niðurstöður okkar benda til þess að áhrif lýsisríks fæðis tilraunadýra séu greinileg þegar sýkt er með Gram neikvæðu bakteríunni Klebsiella pneumoniae en ekki í sýkingum með Streptococcus pneumoniae hjúpgerð 3

Boundary effects on one-particle spectra of Luttinger liquids

We calculate one-particle spectra for a variety of models of Luttinger liquids with open boundary conditions. For the repulsive Hubbard model the spectral weight close to the boundary is enhanced in a large energy range around the chemical potential. A power law suppression, previously predicted by bosonization, only occurs after a crossover at energies very close to the chemical potential. Our comparison with exact spectra shows that the effects of boundaries can partly be understood within the Hartree-Fock approximation.Comment: 4 pages including 4 figures, revised version, to be published in Phys. Rev. B, January 200

Beneficial effect of dietary fish-oil is independent of the infection site

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: Fish-oil enriched diet has a protective effect on experimental animals infected intramuscularly with Klebsiella pneumoniae. It also has beneficial effect in several other diseases, including autoimmune disorders. The pathophysiological effects of dietary fish-oil have still not been revealed although it is expected to influence the immune response. We have previously shown that dietary fish-oil has beneficial effect in mice infected intramuscularly with Klebsiella pneumoniae. If the beneficial effect of dietary fish-oil is due to influence on the immune response it should be independent of the infection site. We therefore investigated whether dietary fish-oil has beneficial effect in intrapulmonary infection with Klebsiella pneumoniae as it has on intramuscular infection with the same bacteria. Materials and methods: Sixty NMRI mice were fed diets enriched with fish-oil (30 mice) or corn-oil (30 mice) for six weeks. The mice were then infected in the lungs with Klebsiella pneumoniae and the survival was monitored. The experiment was performed twice. The results were compared to our earlier results with intramuscular infections. Results: The survival of the mice fed the fish-oil enriched diet and infected in the lungs with Klebsiella pneumoniae was significantly better compared to the survival of mice fed the corn-oil enriched diet in both experiments (p=0.0001 and p=0.0013). These results are similar to our earlier findings when the mice were infected intramuscularly. Conclusions: These results indicate that the beneficial effect of dietary fish-oil on infection is independent of the site of infection. These results are in accordance with the hypothesis that dietary fish-oil influences the immune response.Markmið: Lýsisríkt fæði hefur verndandi áhrif á tilraunadýr sem sýkt eru í vöðva með Klebsiella pneumoniae og hefur einnig áhrif í ýmsum sjúkdómum, þar á meðal sjálfnæmissjúkdómum. Ekki er ljóst á hvern hátt lýsið virkar þó líklegt sé að virknin tengist áhrifum lýsis á ónæmissvar dýranna við sýkingunum og öðru áreiti. Rannsóknarhópurinn hefur áður birt niðurstöður sem sýna verndandi áhrif lýsisneyslu í sýkingum með Klebsiella pneumoniae þegar bakteríunni er sprautað í vöðva. Ef verndandi áhrif lýsis í sýkingum tengjast almennt ónæmissvari líkamans ættu þau að koma fram óháð íkomustað sýkingarinnar. Í tilraunum okkar nú var því kannað hvort lýsið hefði sömu verndandi áhrif á tilraunadýr sem sýkt voru í lungu í stað vöðva eins og það gerði í fyrri tilraunum. Efniviður og aðferðir: Sextíu NMRI mýs voru aldar í sex vikur á fæði bættu með lýsi (30 mýs) eða fæði bættu með kornolíu (30 mýs). Eftir það voru mýsnar sýktar í lungu með Klebsiella pneumoniae og fylgst með lifun. Tilraunin var síðan endurtekin á nákvæmlega sama hátt. Niðurstöðurnar voru bornar saman við fyrri tilraunir hópsins þar sem sýkt var í læri. Niðurstöður: Lifun músa sem fengið höfðu lýsisbætt fæði var marktækt betri í báðum tilraununum samanborið við mýs sem aldar voru á kornolíubættu fæði (p=0,0001 og p=0,0013). Niðurstöðurnar eru sambærilegar fyrri niðurstöðum þegar sýkt var í vöðva. Ályktanir: Niðurstöðurnar benda til að jákvæð áhrif lýsisneyslu komi fram óháð íkomustað bakteríanna. Niðurstöðurnar eru því í samræmi við þá kenningu að lýsisneyslan hafi áhrif á ónæmissvar líkamans fremur en afmarkaða staðbundna þætti

Broiler Chickens as Source of Human Fluoroquinolone-Resistant Escherichia coli, Iceland

To investigate feed as a source for fluoroquinolone-resistant Escherichia coli in broiler chickens, we compared antimicrobial drug–resistant E. coli from broiler feed and broilers with ciprofloxacin-resistant human clinical isolates by using pulsed-field gel electrophoresis. Feed was implicated as a source for ciprofloxacin-resistant broiler-derived E. coli and broilers as a source for ciprofloxacin-resistant human-derived E. coli

Genomic Dissection of an Icelandic Epidemic of Respiratory Disease in Horses and Associated Zoonotic Cases.

Iceland is free of the major infectious diseases of horses. However, in 2010 an epidemic of respiratory disease of unknown cause spread through the country's native horse population of 77,000. Microbiological investigations ruled out known viral agents but identified the opportunistic pathogen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) in diseased animals. We sequenced the genomes of 257 isolates of S. zooepidemicus to differentiate epidemic from endemic strains. We found that although multiple endemic clones of S. zooepidemicus were present, one particular clone, sequence type 209 (ST209), was likely to have been responsible for the epidemic. Concurrent with the epidemic, ST209 was also recovered from a human case of septicemia, highlighting the pathogenic potential of this strain. Epidemiological investigation revealed that the incursion of this strain into one training yard during February 2010 provided a nidus for the infection of multiple horses that then transmitted the strain to farms throughout Iceland. This study represents the first time that whole-genome sequencing has been used to investigate an epidemic on a national scale to identify the likely causative agent and the link to an associated zoonotic infection. Our data highlight the importance of national biosecurity to protect vulnerable populations of animals and also demonstrate the potential impact of S. zooepidemicus transmission to other animals, including humans.IMPORTANCE An epidemic of respiratory disease affected almost the entire native Icelandic horse population of 77,000 animals in 2010, resulting in a self-imposed ban on the export of horses and significant economic costs to associated industries. Although the speed of transmission suggested that a viral pathogen was responsible, only the presence of the opportunistic pathogen Streptococcus zooepidemicus was consistent with the observed clinical signs. We applied genomic sequencing to differentiate epidemic from endemic strains and to shed light on the rapid transmission of the epidemic strain throughout Iceland. We further highlight the ability of epidemic and endemic strains of S. zooepidemicus to infect other animals, including humans. This study represents the first time that whole-genome sequencing has been used to elucidate an outbreak on a national scale and identify the likely causative agent

Subtyping of Salmonella enterica serovar typhimurium outbreak strains isolated from humans and animals in Iceland.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldA total of 75 Salmonella enterica serovar Typhimurium strains of various (mainly human and animal) origins were typed by pulsed-field gel electrophoresis (PFGE) and phage typing. These strains were collected during an outbreak in Iceland in 1999 and 2000. The typing revealed that 84% of the strains belonged to the same PFGE and phage type (PT), namely, PFGE type 1Aa and PT 1

Subtyping of Salmonella enterica Serovar Typhimurium Outbreak Strains Isolated from Humans and Animals in Iceland

A total of 75 Salmonella enterica serovar Typhimurium strains of various (mainly human and animal) origins were typed by pulsed-field gel electrophoresis (PFGE) and phage typing. These strains were collected during an outbreak in Iceland in 1999 and 2000. The typing revealed that 84% of the strains belonged to the same PFGE and phage type (PT), namely, PFGE type 1Aa and PT 1