Light adaptation of cones in rabbits and guinea pigs

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: During light adaptation of the retina, cone electroretinograms (ERGs) can be obtained. It is known that during light adaptation considerable changes occur in the cone ERGs of man, monkeys and mice. All these species have vascular retinae. In the present study we examined whether the same applies to mammalian species with a limited retinal vasculature (rabbits) or avascular retinae (guinea pigs), and which both have two types of cones but scotopic ERGs with completely different morphology. Material and methods: ERGs were recorded from anaesthetized rabbits and guinea pigs with corneal electrodes made from steal wire. Copper wire placed in the mouth of the animal served as reference electrode, and a subcutaneous needle as ground. Recordings were amplified 1000-fold, with bandwidth settings at 1-1000 Hz, and fed into a computer via an A/D converter. Corneas were anaesthetized with a topical application of proparacaine, and pupils dilated with topical application of tropicamide. ERGs were elicited with brief (10 msec) light flashes, and the retina light adapted with a steady white background light. Results: The scotopic b-wave is more than twice the amplitude of the a-wave in rabbits, while the scotopic b-wave in guinea pigs is only slightly larger than the a-wave. The b-wave of the cone ERG is twice the amplitude of the cone a-wave in both species. Once a background light has been turned on, the amplitude increases in both species and the process of light adaptation reaches a peak about 10 minutes thereafter. The b-wave implicit time is shortened by light adaptation in rabbits, but not in guinea pigs. Oscillatory potentials are present in guinea pig ERGs when recorded in dark but not when recorded in light. Conclusions: Mammals that have avascular retinae and which are without long-wavelength cones show evidence of light adaptation of the cone ERG. In guinea pigs the cone ERG increases in amplitude during light adaptation without concomitant shortening of the implicit time. These changes occur at similar rate in rabbits and guinea pigs. The oscillatory potentials in rabbits increase in amplitude but not in guinea pigs. These results suggest that different mechanisms determine the light adaptation of the cone ERG in guinea pigs than in rabbits.Tilgangur: Þegar sjónhimna er aðlöguð að ljósi er hægt að skrá sjónhimnurit (electroretinogram, ERG) keilna. Vitað er að við ljósaðlögun verða miklar breytingar í sjónhimnuriti keilna hjá mönnum, öpum og músum. Þessar tegundir hafa æðar í sjónhimnu. Í þessari rannsókn var athugað hvort sama eigi við um tegundir spendýra með lítið af æðum í sjónu (kanínur) eða engar (marsvín) æðar í sjónu og sem hafa tvær tegundir keilna en alls ólík sjónhimnurit í rökkri. Efniviður og aðferðir: Sjónhimnurit voru skráð frá svæfðum kanínum og marsvínum með skráningarskautum úr stálvír, sem staðsett voru á hornhimnu augans. Koparvír staðsettur í munni var notaður sem viðmiðunarskaut og nál undir húð sem jarðtenging. Skráning var mögnuð 1000-falt, með bandvídd 1-1000 Hz, og niðurstöður fluttar í tölvu með A/D breytikorti. Hornhimna var staðdeyfð með próparakaíni, sjáaldur víkkað með trópikamíð dropum. Sjónhimnurit var vakið með stuttum (10msek) ljósblikkum, og sjónhimna aðlöguð að stöðugu hvítu bakgrunnsljósi. Niðurstöður: Í rökkri er b-bylgja meir en helmingi stærri en a-bylgja í sjónhimnuriti kanína, en b-bylgja aðeins eilítið stærri en a-bylgja hjá marsvínum. Í sjónhimnuriti keilna er hins vegar b-bylgja helmingi stærri en a-bylgja hjá báðum tegundum. Eftir að kveikt er á bakgrunnsljósi eftir aðlögun að rökkri hækkar spenna svara og nær hámarki eftir um 10 mínútur í báðum tegundum. Dvöl b-bylgju styttist hjá kanínum, en ekki hjá marsvínum. Í sjónhimnuriti keilna hjá kanínum eru sveifluspennur (oscillatory potentials), sem stækka að spennu við aðlögun að ljósi. Sveifluspennur eru í sjónhimnuriti marsvína, þegar það er skráð í rökkri, en engar í sjónhimnuriti keilna. Ályktanir: Spendýr með æðalausa sjónhimnu og engar langbylgjukeilur sýna ljósaðlögun sjónhimnurits keilna. Í marsvínum eykst sjónhimnurit keilna að spennu án þess að dvöl breytist við ljósaðlögun. Þessar breytingar eru svipaðar í tíma í kanínum og marsvínum. Sveifluspennur aukast að spennu í kanínum en ekki marsvínum. Niðurstöður benda til að önnur ferli ráði ljósaðlögun sjónhimnurits keilna hjá marsvínum en kanínum

Kilns, Commodities and Consumers: Greco-Roman Pottery Production in Eastern Marmarica (Northwestern Egypt)

The northwestern coastal zone of Egypt is not an area well known for its rich archaeolo­gical record, especially when compared to the adjoining regions like the Cyrenaica in the west and the Nile Valley to the east. As a part of ancient Marmarica it was an ecologically and economically marginal region of semi­arid environmental conditions. However, a remarkably dense pattern of Greco­Roman settlements and agricultural use has been uncovered by recent archaeological and geographical research in the Eastern Marmarica. A surplus economy based on dry farming and livestock can be reconstructed for the hin­ terland of ancient Paraitonion (modern Marsa Matruh). The need to trade agricultural goods such as grapes and/or wine, barley, figs, olives and/or olive oil explains the large number of pottery production sites in the area. This paper will deal firstly with the layout and features of more than forty surveyed pottery production sites, which mainly manufac­tured amphoras, and secondly, the topographical distribution of these sites within the area. Based on these analyses, aspects of the economic organization relating to the transport vessels, the filled goods and the exchange centres of the region can be reconstructed. A preliminary typological and chronological evaluation of the vessels produced closes the discussion.Abb. 5: © DigitalGlobe, Inc. (2005), provided by European Space Imagin

Transcranial magnetic stimulation

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenTranscranial Magnetic Stimulation (TMS) is a new non-invasive method to investigate the central nervous system. Initially it was used to assess the functional integrity of the pyramidal pathways but more recently various other aspects of brain function have been studied including cortical excitability. By localised interference with brain function, it is possible to use TMS to assess the relationship between various brain regions and cognitive functions. The therapeutic effect of TMS has been explored in the treatment of neurological diseases and psychiatric disorders such as epilepsy, cerebellar ataxia and depressive illness.Segulörvun heila í gegnum höfuðkúpu er notuð til rannsókna á miðtaugakerfi. Upphaflega var þessi aðferð þróuð til að meta starfsemi og ástand hreyfitauga­brauta milli heila og mænu, en er nú einnig notuð til margvíslegra rannsókna á heilastarfsemi. Meta má hömlunar- og örvunarástand heilabarkar sem getur breyst vegna heilasjúkdóma og við lyfjagjöf. Með staðbundinni truflun á starfsemi taugafrumna eftir segulörvun hefur verið hægt að kanna tengsl milli heilasvæða og hugrænna ferla. Í ljós hefur komið möguleg notkun segulörvunar í meðferð taugasjúkdóma og geðraskana. Rannsóknir hvað þetta varðar hafa meðal annars beinst að flogaveiki, mænu- og hnykilhrörnun og djúpri geðlægð

A smooth compactification of spaces of stability conditions: the case of the AnA_{n}-quiver

We propose a notion of multi-scale stability conditions with the goal of providing a smooth compactification of the quotient of the space of projectivized Bridgeland stability conditions by the group of autoequivalence. For the case of the 3CY category associated with the $A_n$-quiver this goal is achieved by defining a topology and complex structure that relies on a plumbing construction. We compare this compactification to the multi-scale compactification of quadratic differentials and briefly indicate why even for the Kronecker quiver this notion needs refinement to provide a full compactification.Comment: 42 pages. Any comments welcome

Care-Seeking Pattern among Persons with Depression and Anxiety: A Population-Based Study in Sweden

Background. In primary care, a vast majority of patients affected with depression and anxiety present with somatic symptoms. Detection rate of psychiatric symptoms is low, and knowledge of factors influencing care seeking in persons affected by depressive and anxiety disorders on a population level is limited. Objective. This study aims to describe if persons, affected by depression and anxiety disorders, seek care and which type of care they seek as well as factors associated with care seeking. Method. Data derives from a longitudinal population-based study of mental health conducted in the Stockholm County in 1998–2010 and the present study includes 8387 subjects. Definitions of anxiety and depressive disorders were made according to DSM-IV criteria, including research criteria, using validated diagnostic scales. 2026 persons (24%) fulfilled the criteria for any depressive or anxiety disorder. Results. Forty-seven percent of those affected by depression and/or anxiety had been seeking care for psychological symptoms within the last year. A major finding was that seeking care for psychological symptoms was associated with having treatment for somatic problems. Conclusions. As a general practitioner, it is of great importance to increase awareness of mild mental illness, especially among groups that might be less expected to be affected

Reconstructing and understanding the impacts of storms and surges, southern North Sea

Coastal barriers are ubiquitous globally and provide a vital protective role to valuable landforms, habitats and communities located to landward. They are, however, vulnerable to extreme water levels and storm wave impacts. A detailed record of sub-annual to annual; decadal; and centennial rates of shoreline retreat in frontages characterized by both high (> 3 m) and low (< 1 m) dunes is established for a barrier island on the UK east coast. For four storms (2006–2013) we match still water levels and peak significant wave heights against shoreline change at high levels of spatial densification. The results suggest that, at least in the short-term, shoreline retreat, of typically 5–8 m, is primarily driven by individual events, separated by varying periods of barrier stasis. Over decadal timescales, significant inter-decadal changes can be seen in both barrier onshore retreat rates and in barrier extension rates alongshore. Whilst the alongshore variability in barrier migration seen in the short-term remains at the decadal scale, shoreline change at the centennial stage shows little alongshore variability between a region of barrier retreat (at 1.15 m a$^{−1}$) and one of barrier extension. A data-mining approach, synchronizing all the variables that drive shoreline change (still water level, timing of high spring tides and peak significant wave heights), is an essential requirement for validating models that predict future shoreline responses under changing sea level and storminess.This paper was completed while the first author (SB) was a recipient of a Leverhulme Research Fellowship (RF-2015-045) for a project entitled Development and Application of a shoreline response model. This paper is a contribution to NERC BESS Consortium grant A hierarchical approach to the examination of the relationship between biodiversity and ecosystem service flows across coastal margins (grant reference NE/J015423/1). Table 1 reports information gathered as part of an EU FP7 Collaborative Project (grant agreement no: 603458) Resilience-Increasing Strategies for Coasts – toolkit (http://www.risckit.eu).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/esp.390