Newsgroup: it.discussioni.energie-alternative
Titolo: Gli effetti di Chernobyl sugli animali (effetti delle basse radiazioni)

� pi� piccolo il cervello degli uccelli di Chernobyl
La diminuzione � solo di un 5% ma che � pi� pronunciata sugli esemplari 
giovani.
In particolare si nota che:
�Low dose radiation can have significant effects on normal brain 
development as reflected by brain size and therefore potentially 
cognitive ability.�
http://lescienze.espresso.repubblica.it/articolo/titolo/1346616
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0016862
Background
Animals living in areas contaminated by radioactive material from 
Chernobyl suffer from increased oxidative stress and low levels of 
antioxidants. Therefore, normal development of the nervous system is 
jeopardized as reflected by high frequencies of developmental errors, 
reduced brain size and impaired cognitive abilities in humans. 
Alternatively, associations between psychological effects and radiation 
have been attributed to post-traumatic stress in humans.
Methodology/Principal Finding
Here we used an extensive sample of 550 birds belonging to 48 species to 
test the prediction that even in the absence of post-traumatic stress, 
there is a negative association between relative brain size and level of 
background radiation. We found a negative association between brain size 
as reflected by external head volume and level of background radiation, 
independent of structural body size and body mass. The observed 
reduction in brain size in relation to background radiation amounted to 
5% across the range of almost a factor 5,000 in radiation level. Species 
differed significantly in reduction in brain size with increasing 
background radiation, and brain size was the only morphological 
character that showed a negative relationship with radiation. Brain size 
was significantly smaller in yearlings than in older individuals.
Conclusions/Significance
Low dose radiation can have significant effects on normal brain 
development as reflected by brain size and therefore potentially 
cognitive ability. The fact that brain size was smaller in yearlings 
than in older individuals implies that there was significant directional 
selection on brain size with individuals with larger brains experiencing 
a viability advantage.
Licenza CC.
-- 
Sandro kensan 
www.kensan.it
 geek site

 giovani.
Il link originale non dice affatto che si tratti di "bassi" livelli di 
radiazioni, anzi che molto probabilmente è un effetto dovuto agli alti 
livelli di radiazioni occorsi dopo l' incidente - per quanto una 
riduzione di solo il 5% delle dimensioni dell' organo su una frazione 
di circa il 10% sul campione totale, considerato l' enorme gravità ed 
unicità dell' incidente (mai verificatosi su un reattore occidentale), 
non so che scientificità possa veramente avere
" Stressed birds are able to change the size of some of their organs in 
order to tough out difficult environmental conditions.
For example, migrating birds that have travelled long distances often 
shrink certain organs as they use up energy.
But the brain is the last organ to be sacrificed in this way, say the 
researchers.
Chernobyl forest
Chernobyl is largely human-free but still contaminated with radiation
That suggests the background radiation could be having an even more 
pronounced effect on other organs within the birds.
It is unclear exactly what mechanism is shrinking the birds' brains.
High levels of background radiation cause animals oxidative stress, 
where they have to use antioxidants in their bodies to fight its ill 
effects.
That leaves animals exposed to radiation severely depleted of 
antioxidants, and the reduced brain size may be a result of this 
depletion. "

 non so che scientificitï¿œ possa veramente avere
gli uccelli vissuti e sopravvisuti dopo l'incidente,
dubito che siano ancora in volo.
ben inteso non conosco la vita media degli "uccelli"
felice6pago
vecchio porco
.
-- 
felice_pago
non c\'e\' poverta\' senza difetto

 ben inteso non conosco la vita media degli "uccelli"
Sembra ragionevole ovviamente, ma non è questo il mio punto nè è quello 
dell' articolo originale; semplicemente una percentuale del 10% di 
uccelli su qualche centinaio di esemplari che hanno appena il 5% del 
cervello più piccino lo si può trovare ovunque anche nel centro di 
Milano o di Roma senza scomodare un incidente di dimensioni enormi come 
Chernobyl

 Chernobyl- Nascondi testo citato
IMOH in campania vai piu' sul sicuro
felice6pago
,

 IMOH in campania vai piu' sul sicuro
appunto