The role of stimulus type in age-related changes of visual working memory

Aging is accompanied by increasing difficulty in working memory associated with the temporary storage and processing of goal-relevant information. Face recognition plays a preponderant role in human behavior, and one might therefore suggest that working memory for faces is spared from age-related decline compared to socially less important visual stimulus material. To test this hypothesis, we performed working memory (n-back) tasks with two different visual stimulus types, namely faces and doors, and compared them to tasks with primarily verbal material, namely letters. Age-related reaction time slowing was comparable for all three stimulus types, supporting hypotheses on general cognitive and motor slowing. In contrast, performance substantially declined with age for faces and doors, but little for letters. Working memory for faces resulted in significantly better performance than that for doors and was more sensitive to on-line manipulation errors such as the temporal order. All together, our results show that even though face perception might play a specific role in visual processing, visual working memory for faces undergoes the same age-related decline as it does for socially less relevant visual material. Moreover, these results suggest that working memory decline cannot be solely explained by increasing vulnerability in prefrontal cortex related to executive functioning, but indicate an age-related decrease in a visual short-term buffer, possibly located in the temporal corte

Optimization and development of analytical methods for the determination of new brominated flame retardants and polybrominated diphenyl ethers in sediments and suspended particulate matter

With more stringent legislation on brominated flame retardants, it is expected that increasing amounts of substitutes would replace polybrominated diphenylethers (PBDEs). Therefore, the development and optimization of analytical methodologies that allow their identification and quantification are of paramount relevance. This work describes the optimization of an analytical procedure to determine pentabromochlorocyclohexane, tetrabromo-o-chlorotoluene, 2,3,5,6-tetrabromo-p-xylene, tetrabromophthalic anhydride, 2,3,4,5,6-pentabromotoluene, tris(2,3-dibromopropyl)phosphate, decabromodiphenylethane and 1,2-bis(2,4,6-tribromophenoxy)ethane together with PBDEs in sediments and in suspended particulate matter. This method comprises a pressurized liquid extraction followed by three cleanup steps (gel permeation chromatography and solid phase extraction on Oasis™ HLB and on silica cartridges). Gas chromatography–mass spectrometry, using electron capture negative chemical ionization, is used for the final analysis. The proposed method provides recoveries >85%. The method was applied to sediment and suspended particulate matter samples from different locations in the Western Scheldt estuary (the Netherlands). To the best of our knowledge, this is the first time that the occurrence of the additive flame retardants 2,3,5,6-tetrabromo-p-xylene, 3,4,5,6-tetrabromo-o-chlorotoluene and 2,3,4,5,6-pentabromochlorocyclohexane is reported in the literature. The concentrations of these new flame retardants ranged from 0.05 to 0.30 μg/kg dry weight

Bepaling van potentiele bioaccumuleerbare stoffen met GC-FID/MS en screening van organische verbindingen in effluenten

Onderzoek werd uitgevoerd naar de bepaling van potentieel bioaccumuleerbare verbindingen (PBS) in effluenten die afkomstig waren van bedrijven uit Engeland, Ierland, Protugal, België en Nederland. Hierbij werd gebruik gemaakt van SPME-extractie gecombineerd met een GC-FID/MS detectie. Kwantificering met FID was betrouwbaarder (V.C. 7-41%) dan met MS (V.C. 15-130%) wat veroorzaakt werd door de stabielere basislijn van het FID-chromatogram. De aangetroffen PBS gehalten varieerden tussen de 1,2 en 21 mM voor GC-FID en liggen lager dan de acute narcotische toxiciteitswaarden voor watervlo, alg en vis. Een aantal effluenten bevatten echter gehalten die mogelijk chronische narcotische toxiciteit kunnen veroorzaken

Euroopa Liidu julgeolekupoliitika integratsioon ühises julgeoleku- ja kaitsepoliitikas osalevate riikide näitel

Selleks et seista silmitsi ja ennetada julgeolekuohte ning kaitsta Euroopa huvisfääri, on oluline Euroopa Liidu ühise julgeoleku- ja kaitsepoliitika (CSDP) eesmärgipärane toimimine ja vajadusel kiire rakendamine. Sellest tulenevalt on käesoleva töö eesmärgiks välja selgitada Euroopa Liidu julgeolekuintegratsiooni peamised võimaldajad ja takistajad ehk tegurid, mis aitavad kaasa või pidurdavad julgeolekuintegratsiooni edasist arengut. Lisaks esitatakse rakenduslikke ettepanekuid CSDP eesmärgipäraseks toimimiseks. Esmalt antakse töös ülevaade EL-i julgeolekuintegratsiooni arengust ning seejärel käsitletakse kolme peamist Euroopa inegratsiooniteooriat - neofunktsionalismi, liberaalset valitsustevahelist teooriat ning konstruktivismi. Töö uurimiseesmärgi saavutamiseks kasutati juhmiuuringut ning viidi läbi 13 poolstruktureeritud ekspertintervjuud nii Eesti- kui ka välisekspertidega. Analüüsi tulemusel selgus, et CSDP integratsiooni peamiseks takistajaks on selle valitsustevaheline iseloom, sest erinevate huvide ja ohutunnetuste tõttu ei suudeta kiiresti reageerida ning CSDP-d rakendada. Samas annab valitsustevaheline iseloom liikmesriikidele võimaluse oma huvide ja poliitikate realiseerimiseks ning otsuste mõjutamiseks. Peamisteks võimaldavateks teguriteks on ühiselt konstrueeritud väärtused, nagu moraal, eetika, humanitaarsus. Ühise visiooni, plaanide ja strateegiate puudumine tingib CSDP toimimise juhuslikult ning sõltuvuse üksikute liikmesriikide huvidest. CSDP eesmärgipäraseks toimimiseks on vajalik edasine koostöö ja koordinatsioon NATO ja CSDP vahel ning lahingugruppide rakendamine. Sellest lähtuvalt tehakse töös järgmised ettepanekud CSDP eesmärgipäraseks toimimiseks: (1) sõjalise koostöö arendamine väiksemates poliitiliselt ja kultuuriselt sarnastest riikide liitudes; (2) teatud pädevuse delegeerimine EL-i institutsioonidele; (3) lahingugruppide rakendamine operatsioonidel ning nende kasutamise muutmine paindlikumaks; (4) EL-i alalise ümberpaigutatava operatsioonide peakorteri loomine; (5) varustuse ja väljaõppe ühtlustamine, et vähendada liikmesriikide operatsioonidel osalemise kulutusi; (6) liikmesriikide vahel kokkulepete sõlmimine ühistes visioonides, ohtudes ja meetmetes ning EL-i julgeolekustrateegia kaasajastamine.http://www.ester.ee/record=b450455

Search for the evidence of endocrine disruption in the aquatic environment: Lessons to be learned from joint biological and chemical monitoring in the European Project COMPREHEND

Between January 1999 and December 2001, the European Community project COMPREHEND was performed. The overall aim of COMPREHEND was to assess endocrine disruption in the aquatic environment in Europe, consequent to effluent discharge, with emphasis on estrogenic activity. COMPREHEND demonstrated the widespread occurrence of estrogenic effluents across Europe and presented evidence of impacts on a range of wild fish species. Using a variety of bioassays in combination with chemical analytical methods, estrogenic steroids of human origin from domestic wastewater effluents were identified as the most pervasive problem, although alkylphenols may be important estrogenic components of some industrial effluents. New tools have been developed for the identification of estrogenic effluents, and recommendations are made for the improvement of existing techniques. We have shown that individual fish within natural populations may be feminized to varying degrees, but it has not been possible to show, using traditional fish population parameters, that the survival of fish populations is threatened. However, laboratory-based fish life-cycle studies demonstrate the sensitivity of fish to estrogen (and androgen) exposure and how this might lead to complex (and potentially damaging) genetic changes at the population level. New approaches to this problem, utilizing recent advances made in the field of molecular and population genetics, are recommended. Finally, a study of estrogenic and androgenic activity of waste waters during the treatment process has shown that some of the existing wastewater treatment technologies have the potential to eliminate or minimize the hormonal activity of the final effluent