Beyond Technological Diversification: The Impact of Employee Diversity on Innovation

This paper investigates the effect of employee diversity in terms of gender, age, ethnicity and education on the firm’s likelihood of introducing an innovation. The analysis draws on data from a recent innovation survey. This data is merged with a linked employer-employee dataset that allow us to identify the employee composition of each firm. We test the hypothesis that employee diversity is associated with better innovative performance. The econometric analysis reveals positive, negative and non-significant effects of the different employee characteristics on the likelihood of introducing an innovation.Diversity, Innovation, Education, Gender, Cultural Backgrund

THz laser based on dipolaritons

We develop the microscopic theory of a terahertz (THz) laser based on the effects of resonant tunneling in a double quantum well heterostructure embedded in both optical and THz cavities. In the strong coupling regime the system hosts dipolaritons, hybrid quasiparticles formed by the direct exciton, indirect exciton and optical photon, which possess large dipole moments in the growth direction. Their radiative coupling to the mode of a THz cavity combined with strong non-linearities provided by exciton-exciton interactions allows for stable emission of THz radiation in the regime of the continuous optical excitation. The optimal parameters for maximizing the THz signal output power are analyzed.Comment: 8 pages, 7 figure

Managing warfarin treatment in a small Icelandic rural practice in Húsavík

Hægt er að lesa greinina í heild sinni með því að smella á hlekkinn View/OpenOBJECTIVE: To investigate the efficiency of warfarin management in Húsavík Health Care Center. MATERIAL AND METHODS: All patients receiving warfarin treatment managed in Húsavík in the years 2001 and 2003 were included in the study. Main outcome measures were the percentage time within INR target range (Rosendaal) and whether the management was deemed satisfactory or unsatisfactory (defined as <3 measurements per year). RESULTS: In 2001 there were 34 patients receiving warfarin treatment in Húsavík but 57 in 2003. Median age was 71.5 and 76 years, 65% and 67% were males, indication for treatment was atrial fibrillation in 53% and 73% and INR target range was 2.0-3.0 in 74% and 86% respectively. The management was deemed unsatisfactory in 38.2% in 2001 but 10.5% in 2003 (27.7% absolute reduction, p=0.0017). Percentage time spent within target range was 61.2% and 63.1% respectively. CONCLUSION: These findings suggest that the quality of anticoagulant control in Húsavík is adequate and fully comparable with that shown in previous studies from our neighbouring countries.Tilgangur: Að athuga hversu vel gengi að stýra blóðþynningarmeðferð með warfaríni frá Heil­brigðisstofnun Þingeyinga (HÞ) samanborið við aðrar rannsóknir og hvort breytingar sem urðu á framkvæmd eftirlitsins árið 2002 hefðu orðið til bóta. Niðurstöður: Árið 2001 voru 34 sjúklingar á blóðþynningarmeðferð sem stýrt var frá HÞ en 57 árið 2003. Miðgildi aldurs var 71,5 og 76 ár, karlar voru 22 (65%) og 38 (67%). Ábending meðferðar var gáttatif í 53% og 73% tilvika og markgildi INR var 2-3 í 74% og 86% tilvika. Árið 2001 voru 13 af 34 sjúklingum (38,2%) undir ófullnægjandi eftirliti en árið 2003 voru þeir 6 af 57 (10,5%). Munurinn var því 27,7% (p=0,0017). Sjúklingarnir voru 61,2% og 63,1% tímans innan markgildis og meðal mæl­ingafjöldi var sex árið 2001 en 12 árið 2003. Eitt tilvik blóðtappa í heila var árið 2001 og eitt tilvik blæðingar sem krafðist innlagnar árið 2003. Ályktanir: Stjórnun blóðþynningarmeðferðar á HÞ er sambærileg því sem gerist erlendis og betur gengur að halda sjúklingum á meðferð í fullnægjandi eftirliti eftir að breytt var um fyrirkomulag

Control of electronic transport in graphene by electromagnetic dressing

We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) electronic transport in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control electronic properties of graphene with light.Comment: Published versio

Measuring corruption: whose perceptions should we rely on? Evidence from Iceland

The extent of corruption in Iceland is highly contested. International corruption measures indicate a relatively small amount of corruption while domestic public opinion suggest a serious corruption problem. Thus, uncertainty prevails about the actual extent of corruption and whose perceptions to rely on. This problem is relevant for corruption research in general. Perceptions are increasingly used as proxies for the actual levels of corruption in comparative research. But we still do not know enough about the accuracy of these proxies or the criteria they must meet in order to give dependable results. In fact, radical differences exist concerning evaluations of perceptions between those who believe in unbiased learning and those believing perceptual bias to be widespread. The purpose of this article is, therefore, to attempt to gauge which factors may influence how perceptions of corruption are shaped and why differences in corruption perceptions between different groups may be so pronounced. We present findings from original survey data from three parallel surveys – among the "public", experts, and "municipal practitioners" – conducted in Iceland in 2014. Expectations based on the perceptual bias approach are tested, indicating that perceptions may be affected by (1) information factors, (2) direct experience of corruption and (3) emotive factors. The validity of perception measures should be considered with this in mind. Domestic experts are likely to be well informed and avoid perceptual bias to a greater extent than other groups. Our examination of the Icelandic case suggests that the Corruption Perception Index (CPI) tends to underestimate corruption problems in "mature welfare states", such as Iceland, whilst the general public tends to overestimate it.Peer ReviewedRitrýnt tímari

Refractive surgery - a review

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenRefractive errors, such as myopia, hyperopia and astigmatism, are very common all over the world. Refractive surgery started in the latter half of the twentieth century and over the last one or two decades refractive surgery with lasers has become popular. Refractive surgery for myopia flattens the cornea of the eye and decreases its refractive power. Surgery for hyperopia on the other hand increases the curvature of the cornea and increases the refractive power. Today this is most frequently done with a lasik procedure where a flap is lifted of the cornea and the laser surgery performed underneath the flap.Sjónlagsgallar, það er nærsýni, fjarsýni og sjónskekkja (astigmatismi), eru mjög algengir um allan heim og annar til þriðji hver maður notar gleraugu eða snertilinsur. Tilraunir til að leiðrétta sjónlagsgalla með skurðaðgerð hófust á seinni hluta tuttugustu aldar og á síðustu árum hafa leysiaðgerðir við sjónlagsgöllum náð miklum vinsældum. Oftast er gert við nærsýni en einnig sjónskekkju og fjarsýni. Aðgerð gegn nærsýni beinist að því að fletja hornhimnu augans og minnka þar með ljósbrot hennar en í fjarsýnisaðgerð er hornhimnan gerð kúptari til að auka ljósbrotið. Nú til dags er þetta yfirleitt gert með leysigeisla eftir að flipa hefur verið lyft af hornhimnunni. Leysiaðgerðir við sjónlagsgöllum eru algengar um allan heim og að minnsta kosti í Bandaríkjunum er boðið upp á sérnám í þessari grein augnlækninga. Íslenskir augnlæknar biðu átekta með að hefja slíkar aðgerðir hér heima þar til nægilega löng og góð reynsla lægi fyrir í nágrannalöndum en nú er farið að gera leysiaðgerðir við sjónlagsgöllum á Íslandi

Quinolone resistance in Gram negative rods in Iceland and association with antibiotic use

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenOBJECTIVE: Fluoroquinolones are bacteriocidal drugs that are widely used to treat severe urinary and respiratory tract infections. Studies show that resistance to fluoroquinolones is continuously increasing both in Europe and the United States. The purpose of this study was to measure the frequency of fluoroquinolone resistance in the most prevalent Gram negative rods and look at the correlation with fluoroquinolone use over the last 8 years. MATERIALS AND METHODS: All strains of Escherichia coli, Klebsiella sp., Proteus sp. and Pseudomonas aeruginosa identified from clinical specimens at the Department of Clinical Microbiology at the Landspitali University Hospital (LUH) during the time period 1.11.2006 to 31.1.2007. Antibiotic susceptibility testing was performed by disc diffusion tests and all strains were tested for ciprofloxacin susceptibility. Antibiotic resistance data for the last years were collected from the reports of the Department of Clinical Microbiology, but ciprofloxacin susceptibility was usually only tested for specimens from hospitalised patients and when there was resistance to two or more antimicrobial agents. Data on antibiotic use/sales was obtained from the State Epidemiologist at the Directorate of Health. RESULTS: Of the 1861 strains tested, 104 fluoroquinolone resistant strains were identified during the study period, including 91 E. coli (87%), 8 Klebsiella sp. (8%) and 5 P. aeruginosa (5%). No fluoroquinolone resistant Proteus sp. was identified. There was a significant positive correlation between fluoroquinolone use and the frequency of resistant strains of E. coli and Enterobacteriaceae. The frequency of resistant E. coli strains was 6% and it differed significantly between age groups (p >0.001) and sex, 6% for females and 11% for males (p = 0.015). The ratio of fluoroquinolone resistant E. coli was highest in the LUH and homes for the elderly. CONCLUSION: The frequency of fluoroquinolone resistance is increasing fast in Iceland but is still one of the lowest compared to the other European countries. The frequency is highest in the oldest age groups where the use of the quinolones is the greatest and there was a significant correlation between the quinolone use and the frequency of resistance in E. coli and Enterobacteriaceae. The results highlight the importance of prudent fluoroquinolone use and the need to monitor fluoroquinolone use and resistance.Tilgangur: Flúórókínólón eru bakteríudrepandi lyf og mikið notuð við meðhöndlun alvarlegra þvagfæra- og öndunarfærasýkinga. Kannanir sýna að ónæmi gegn flúórókínólónum eykst stöðugt bæði í Evrópu og Bandaríkjunum. Tilgangur rannsóknarinnar var að skoða ónæmi fyrir flúórókínólónum hjá algengustu Gram neikvæðu stöfunum ásamt tengslum þess við notkun flúóró-kínólóna síðastliðin átta ár. Efniviður og aðferðir: Rannsóknin náði til allra stofna Escherichia coli, Klebsiella sp., Proteus sp. og Pseudomonas aeruginosa sem greindust sem líklegir sýkingarvaldar í innsendum sýnum á sýklafræðideild Landspítalans á tímabilinu 1.11.2006 til 31.1.2007. Næmispróf voru framkvæmd með skífuprófum og var næmi fyrir cíprófloxacíni prófað hjá öllum stofnunum. Gögn um tíðni ónæmis síðastliðin ár voru fengin úr skýrslum sýklafræðideildar, en að jafnaði var aðeins prófað fyrir cíprófloxacín næmi hjá inniliggjandi sjúklingum og þeim sem höfðu ónæmi fyrir tveimur eða fleiri lyfjaflokkum. Upplýsingar um sýklalyfjanotkun fengust frá sóttvarnalækni. Niðurstöður: Af þeim 1861 stofni sem voru prófaðir á tímabilinu reyndust 104 vera flúóró-kínólón-ónæmir stofnar. Þar af voru 91 E. coli (87%), 8 Klebsiella sp. (8%) og 5 P. aeruginosa (5%). Enginn flúórókínólón-ónæmur Proteus sp. greindist. Marktæk jákvæð fylgni var á milli flúórókínólón-notkunar og tíðni ónæmra E. coli og Enterobacteriaceae stofna. Tíðni ónæmra E. coli stofna var 6% en marktækur munur var á tíðninni eftir aldurshópum (p>0,001). Einnig var marktækur munur á tíðni E. coli milli kynja en hún var 6% hjá konum en 11% hjá körlum (p=0,015). Hlutfall flúórókínólón ónæmra E. coli stofna var hæst á Landspítala og elliheimilum. Ályktanir: Tíðni flúórókínólón-ónæmis er að auk-ast á Íslandi en er þó enn með því lægsta sem gerist í Evrópu. Tíðnin er hæst í eldri aldurshópum þar sem flúórókínólón-notkun er mest og marktæk fylgni er á milli notkunar og tíðni ónæmis hjá E. coli og Enterobacteriaceae. Niðurstöðurnar sýna mikilvægi þess að flúorókínólónin séu rétt notuð og að fylgst sé með notkun þeirra og ónæmi fyrir þeim. Draga þarf úr notkun flúórókínólóna til að hægja á útbreiðslu ónæmis

Neurodegenerative diseases, antioxidative enzymes and copper. A review of experimental research

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenIntroduction: In almost all degenerative diseases of the brain aggregation of proteins inside neurons or extracellulary, is a common pathological phenomenon regardless of etiology. It is assumed that the biochemical pathways leading to aggregation are more harmful than the aggregations themselves and most likely imply production of free oxygen radicals. This oxidative stress is in the body met by free radical scavengers in the form of specific chemical substances and antioxidative enzymes. It has therefore been postulated that defective free radical defense is a common pathway in most neurodegenerative diseases in humans as well as in other mammals. Material and methods: The concentration of copper and the activity of two antioxidative copper containing enzymes, ceruloplasmin and superoxide dismutase (SOD 1), was analyzed in the blood. A series of case control studies were performed in Alzheimer´s disease (AD), Parkinson´s disease (PD) and amyotrophic lateral sclerosis (ALS) as well as in Down´s syndrome and autism. Furthermore, a study in sheep was conducted in different areas with different risks of infection of scrapie. In that study, in addition, the activity of the selenium-containing enzyme, glutathione peroxidase, was determined as well as the concentration of manganese in blood. Results: The oxidative activity of ceruloplasmin and SOD1 was shown to be significantly lowered in Alzheimer´s disease without any signs of copper deficiency. In Parkinson´s disease, the oxidative activity of ceruloplasmin was also on the whole shown to be signifcantly lowered, and furthermore, it decreased significantly as well as the SOD1 activity with duration of the disease. In ALS, the means of all of the determinations were shown to be the same, but the equality of variances differed significantly in the patients compared to their controls. In Down´s syndrome past the age of 40, when Alzheimer´s type changes appear in the brain, the SOD1 activity and the ceruloplasmin specific oxidative activity (activity in relation to concentration) was significantly lowered compared with the younger patients. In autism, a non-degenerative affection of the central nervous system, there was no difference between patients and their controls. In the sheep, the results indicated a relationship between decreased glutathione peroxidase activity, and possibly also SOD1 activity, and increased susceptibility to scrapie infection. No connection was found between ceruloplasmin oxidative activity and susceptibility to scrapie infection. Susceptibility to scrapie infection was apparantly not conntected with low levels of copper or high levels of manganese in blood of the animals. Discussion: The results indicate that the oxidative defenses in four neurodegenerative diseases with different clinical features are defective as the activity of two copper containing antioxidative enzymes, ceruloplasmin and SOD1, was found defective in all of them. In a developmental syndrome (autism), where neither active degenerative changes nor aggregations are found, no such changes in enzyme activity were detected. The results thus support the idea that deranged oxidative defense is a common denominator in the pathogenesis of these diseases. As far as sheep is concerned, the results also indicate, that there is a defect in oxidative defense connected with increased susceptibility to scrapie infection in the form of lowered glutathione peroxidase activity.Inngangur: Hrörnunarsjúkdómar í miðtaugakerfi eiga langflestir það sameiginlegt að í þeim á sér stað samsöfnun og útfelling á próteinum í taugafrumum eða utan við þær hver sem orsökin kann að vera. Talið er að efnabreytingar, sem eru undanfari samsöfnunar og útfellinga, séu skaðvaldurinn fremur en útfellingarnar sjálfar. Efnabreytingar þessar leiða að öllum líkindum til myndunar á skaðlegum súrefnisfríhópum. Oxavarnir líkamans, sem bæði taka til sértækra efna og oxavarnarensíma, vinna gegn þessu ferli og því hefur þeirri tilgátu verið varpað fram að veiklaðar oxavarnir séu sameiginlegur þáttur í meingerð hrörnunarsjúkdóma í miðtaugakerfi, hvort sem er í mönnum eða öðrum spendýrum. Aðferðir: Magn kopars og virkni tveggja oxavarnandi ensíma sem innihalda kopar, cerúlóplasmíns og súperoxíðdísmútasa 1 (SOD1), var ákvarðað í blóðinu. Gerðar voru tvenndarrannsóknir er tóku til Alzheimer sjúkdóms, Parkinson sjúkdóms, hreyfitaugungahrörnunar og sjúklinga með Downs heilkenni auk sjúklinga með einhverfu. Einnig var gerð rannsókn á sauðfé á mismunandi svæðum með mismunandi líkum á riðusmiti. Í þeirri rannsókn var að auki ákvörðuð virkni glútatíonperoxídasa sem er selenríkt oxavarnarensím og magn mangans ákvarðað í blóðinu. Niðurstöður: Oxunarvirkni cerúlóplasmíns og virkni SOD1 var marktækt minni í Alzheimer sjúkdómi án þess að rekja mætti það til vöntunar á kopar. Í Parkinson sjúkdómi var virkni cerúlóplasmíns einnig marktækt minni og virkni bæði cerúlóplasmíns og SOD1 minnkaði marktækt með sjúkdómslengd enda þótt kopar væri innan eðlilegra marka. Í hreyfitaugungahrörnun var breytileiki einstakra mælingargilda cerúlóplasmíns og SOD1 marktækt öðruvísi en ekki var munur á meðaltölugildum. Í einstaklingum með Downs heilkenni sem voru 40 ára og eldri og því komnir á þann aldur að Alzheimerlíkra breytinga er að vænta í heilanum, var virkni SOD1 og sértæk virkni cerúlóplasmíns (virkni í hlutfalli við magn) marktækt minni en í yngri hluta hópsins. Í einhverfu, sem einkennist af þroskahefti fremur en vaxandi hrörnunareinkennum, var hins vegar enginn munur á sjúklingum í samanburði við heilbrigða einstaklinga. Niðurstöður rannsókna á sauðfé bentu til þess að samhengi gæti verið milli aukinnar hættu á riðusmiti og minnkandi virkni glútatíonperoxídasa og hugsanlega einnig minnkandi SOD1 virkni. Engin marktæk tengsl voru að því er virtist milli aukinnar hættu á riðusmiti og breytinga á virkni cerúlóplasmíns. Aukin hætta á riðusmiti varð ekki tengd við litla þéttni kopars eða mikla þéttni mangans í blóði fjárins. Umræða: Rannsóknirnar benda til þess að oxavarnir séu veiklaðar í þeim fjórum hrörnunarsjúkdómum í miðtaugakerfi manna sem rannsakaðir voru þótt klínísk mynd þeirra sé ærið ólík, en greina mátti minnkaða eða afbrigðilega virkni oxavarnandi koparensíma í blóði við alla þessa sjúkdóma. Í ástandi sem telst vera þroskahefti (einhverfa) og er án virkra hrörnunarbreytinga eða útfellinga í heila er ekki að finna slíkar breytingar. Niðurstöðurnar styðja því þá tilgátu að veiklaðar oxavarnir séu sameiginlegur þáttur í meingerð þessara sjúkdóma. Varðandi sauðfé benda niðurstöður einnig til þess að veiklun sé í oxavörnum samfara auknum líkum á riðusmiti þótt það verði að líkindum einkum tengt minnkaðri virkni glútatíonperoxídas