Resonant scattering of light in a near-black-hole metric

We show that low-energy photon scattering from a body with radius R slightly larger than its Schwarzschild radius r_s resembles black-hole absorption. This absorption occurs via capture to one of the many long-lived, densely packed resonances that populate the continuum. The lifetimes and density of these meta-stable states tend to infinity in the limit r_s -> R. We determine the energy averaged cross-section for particle capture into these resonances and show that it is equal to the absorption cross-section for a Schwarzschild black hole. Thus, a non-singular static metric may trap photons for arbitrarily long times, making it appear completely `black' before the actual formation of a black hole.Comment: 6 pages, 4 figure

Bioprospecting for plant and fungus extracts with systemic effect to control the cucumber powdery mildew.

This work was aimed to select plant and fungus extracts showing systemic effect to control the cucumber powdery mildew. For that, ethanolic extracts were obtained from five basidiomycetes and 71 plant species and tested under greenhouse conditions. Cucumber plants cv. 'Safira' were sprayed with extracts at the first true leaf growth stage and inoculated with Sphaerotheca fuliginea at the second leaf growth stage. The number, diameter and sporulation rate of powdery mildew colonies were evaluated 6 days after inoculation. In an initial screening phase, the extracts of the following plants and fungi revealed some systemic effect against the powdery mildew: Aloe vera (aloe), Bidens pilosa, Ganoderma sp. (basidiomycete), Hyptis crenata, Mascagania betbamiana, Ocotea suaveolens, Oudemansiella canarii (basidiomycete), Pinus taeda (pine), Riehardia grandiflora and Vernonia polyanthes. They were compared in three other experiments and those from Oudemansiella, Ganoderma, pine needles and aloe leaves were the most efficient reducing the number of colonies on the secondary leaf by 79, 65, 30 and 21 %, respectively. Extracts from fruiting bodies of Oudemansiella and Ganoderma also decreased the diameter of colonies by 20 % as well as the sporulation rate by 45 and 70 %, respectively. While Ganoderma did not show any direct effect in vitro, the extract of Oudemansiella (60 mg fresh weight ml[-1]) reduced the germination of powdery mildew conidia at 48 h after inoculation by 71 %. Furthermore, Oudemansiella-extract strongly inhibited the mycelium growth of Cladosporium oxysporum in liquid medium. The possible modes of action of these extracts are discussed

Controle da podridão cinzenta da maçã por produtos naturais biologicamente ativos

Indexación: Web of Science; ScieloBiorend SC (chitosan), BC-1000 EC (grapefruit extract plus bioflavonoids) and ECO-100 SC (bioflavonoids plus organic acids, citric phytoalexins, fatty acids, glycerides and sugars), respectively, suppressed grey rot of apple caused by B. cinerea by 80.1%, 79.0% and 76.5% when used as post-harvest treatments under controlled conditions. When applied as combined pre- and post-harvest treatments Biorend SC inhibited fruit rot by 49.9 %, while BC-1000 EC and ECO-100 SC were ineffective. None of the products inhibited fruit rot when applied as pre-harvest treatments under controlled conditions or as post-harvest treatments under commercial conditions. The algal polysaccharide ulvan used in post-harvest treatments suppressed grey rot by 56.0% under controlled conditions, but had no inhibitory effect on combined pre- and post-harvest treatments. The inability of products to activate defense mechanisms (chitinase and peroxidase) of fruits was consistent with the unsuccessful control of rot by pre-harvest treatment. The results suggest that the natural products used have potential for use in integrated management of Botrytis rot when applied after harvest.Biorend SC (quitosana), BC-1000 EC (extrato de toranja mais flavonóides), e ECO-100 SC (bioflavonóides mais ácidos orgânicos, fitoalexinas cítricas, ácidos graxos glicerídeos e açúcares) inibiram em 80,1%, 79,0% e 76,5%, respectivamente, a podridão causada por Botrytis cinerea quando utilizados no tratamento pós-colheita de frutos de maçã sob condições controladas.Tratamento combinado de Biorend SC, com aplicação tanto em pré como no pós-colheita, proporcionou 49,9% de inibição da podridão, enquanto BC-1000 e ECO-100 EC não foram efetivos. Nenhum desses produtos inibiu a podridão cinzenta, quando utilizados em tratamento de pré-colheita em condições controladas ou em tratamento de pós-colheita em condições comerciais. O polissacarídeo algal ulvana, utilizado nos tratamentos de pós-colheita, reduziu em 56% a podridão cinzenta das maçãs em condições controladas, mas não teve efeito inibitório nos tratamentos combinados de pré e pós-colheita. A incapacidade dos produtos em ativar mecanismos de defesa (quitinases e peroxidases) nos frutos, após o tratamento em pré-colheita, foi consistente com a falta de controle da podridão nesse tipo de ensaio. Pelos resultados, sugere-se que os produtos naturais utilizados apresentam potencial para a utilização no manejo integrado da podridão de Botrytis quando aplicados em pós-colheita.http://ref.scielo.org/kcxb9

Effect of sonication on technological properties of beef

Обробка м’яса ультразвуком у період трупного задубіння призводить до прискорення процесів старіння (пом’якшення тканин). Ця обробка істотно не впливала на кислотність тканини та на втрату ваги, але поліпшувала ніжність м’яса. Визначені технологічні властивості досліджених зразків можуть бути наслідком впливу ультразвуку на структуру білків м’яса. Внаслідок обробки ультразвуком відбулося збільшення концентрації вільних іонів кальцію. Отримані результати показали, що обробка ультразвуком може бути ефективним методом формування технологічних властивостей яловичини.Обробка м’яса ультразвуком у період трупного задубіння призводить до прискорення процесів старіння (пом’якшення тканин). Ця обробка істотно не впливала на кислотність тканини та на втрату ваги, але поліпшувала ніжність м’яса. Визначені технологічні властивості досліджених зразків можуть бути наслідком впливу ультразвуку на структуру білків м’яса. Внаслідок обробки ультразвуком відбулося збільшення концентрації вільних іонів кальцію. Отримані результати показали, що обробка ультразвуком може бути ефективним методом формування технологічних властивостей яловичини.Ultrasound treatment during rigor mortis period led to an acceleration of aging processes. No significant influence of sonication on acidity during ageing was observed. Ultrasound treatment did not influence the lightness, but according to the shear force measurements, improve meat tenderness. Differentiated technological properties of examined samples may result from influence of ultrasound on protein structures of meat. As a result of ultrasound treatment an increase of free calcium ions concentration occurred. Obtained results pointed out that sonication may be an effective method of formation of technological properties of beef during ageing