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81.
Summary The interplanetary perturbations associated with Forbush decreases (FDs) during the period 1965–1974 are studied. The systematic
appearance of the results obtained confirms once again that type-IV solar flares are the origin of these perturbations. The
front perturbation is a wide (∼100° in longitude) driven shock followed by a magnetic blob and a high-speed plasma cloud of
about 0.5 A.U. average radial dimension at the Earth orbit, emitted in a short time interval (<15 h) immediately following
the beginning of the type-IV burst. The FD-modulated region is found to be included between two boundary streams which rotate
with the Sun; therefore the FD can be observed also in the interplanetary regions which were not swept by the front perturbation.
The FD amplitude appears to be correlated with an empiric parameter which caters for the importance of the shock and magnetic
blob at the front perturbation.
Riassunto Le perturbazioni interplanetarie associate alle diminuzioni di Forbush (FDs) sono state studiate per il periodo 1965–1974. L’insieme dei risultati ottenuti conferma che i brillamenti solari accompagnati da radioemissione di tipo IV sono all’origine di queste perturbazioni. II fronte della perturbazione è un’onda d’urto di estensione ∼100° in longitudine seguita da campo magnetico esaltato (?magnetic blob?) e da una nuvola di plasma ad alta velocità, di dimensione media radiale ∼0.5 A.U. all’orbita della Terra, emessa per un intervallo di tempo breve (,15 ore) dopo l’inizio della radioemissione di tipo IV. Si trova che la regione modulata della FD è limitata da due fasci di vento solare veloce che coruotano con il Sole; la FD può essere perciò anche osservata nelle regioni di spazio interplanetario che non sono state investite direttamente dal fronte della perturbazione. L’ampiezza della FD appare correlata con un parametro empirico che tiene conto dell’importanza dell’onda d’urto e del ?magnetic blob? presenti al fronte della perturbazione.
Резюме Исследуются межпланетные возмущения, связанные с убываниями Форбуша в течение периода 1965–1974 г.г. Получается систематическое подтверждение того факта, что солнечные вспышки типа IV связаны с этими возмущениями. Фронт возмущения представляет широкую (∼100° по долготе) ударную волну, за которой следует магнитое ?пятно? и плазменное облако со средним радиальным размером 0.5 а.е.д. на орбите Земли, испускаемые в течение короткого временного интервала (<15 часов) непосредственно за началом вспышки типа IV. Область, модулированная убываниями Форбуша, заключена между двумя граничными потоками, которые вращаются вокруг Солнца. Таким образом, убывания Форбуша могут наблюдаться также в межпланетных областях, через которые не проходит фронт возмущения. Оказывается, что амплтуда убываний Форбуша коррелирует с змпирическим параметром, который определяет значимость ударной волны и магнитного ?пятна? на возмущение Форбуша.相似文献
82.
83.
Two-dimensional imaging of current filament patterns generated in homogeneousn-type GaAs during avalanche breakdown at low temperatures is reported. The self-generated formation and subsequent growth behavior of distinct single- and multifilament configurations could globally be visualized by means of a scanning electron microscope equipped with a liquid-helium stage. From local conductivity measurements in the smallest possible filaments (typical diameter of about 10 m) carrier mobilities as high as about 4·106 cm2/Vs at 4.2 K were estimated. Such high-mobility filament channels may become interesting for applications in ultrafast electronic circuits. 相似文献
84.
85.
A spectrum evaluator based on four different dosimeter materials has been employed to estimate the spectral irradiances of solar radiation for exposed humans. The result is used to calculate the biologically effective irradiance using the erythemal action spectrum and a fish melanoma action spectrum. Measurements are made in winter at a sub-tropical site on the chest and shoulder of subjects during normal daily activities. Up to 95% of the total UV exposure received is in the UV-A waveband (320-400 nm). The UV-A waveband is found to contribute approximately 14% of the erythemal UV and 93% of the biologically effective UV for fish melanoma. Extrapolation to humans suggests that exposure to the UV-A band will contribute to photodamage in human skin during exposure to solar radiation. 相似文献
86.
87.
A new perspective on traditional energy minimization problems is provided by a connection between statistical thermodynamics and combinatorial optimization (finding the minimum of a function depending on many variables). The joint use of a new method for uncovering the global minimum of intramolecular potential energy functions, based on following the asymptotic behavior of a system of stochastic differential equations, and an iterative-improvement technique, whereby a search for relative minima is made by carrying out local quasi-Newton minimizations starting from many distinct points of the energy hypersurface, proved most effective for investigating the low-energy conformational space of molecules. 相似文献
88.
89.
Polysulphone dosimeters using a simple to use filter have been developed and tested to provide an extended dynamic measurement range of personal solar UV exposures over an extended period (3 to 6 days). At a Southern Hemisphere subtropical site (27.6 degrees S, 151.9 degrees E), the dynamic range of the filtered polysulphone allowed measurements of erythemal exposures to approximately 100 minimum erythemal dose (MED) for a change in optical absorbance at 330 nm (deltaA330) of 0.35. In comparison, unfiltered polysulphone dosimeters were exposed to approximately 8 MED for the same deltaA330. The error associated with the use of the filtered polysulphone dosimeters is of the order of +/-15%, compared with +/-10% of the unfiltered variety. The developed filtered polysulphone dosimeter system allowed the measurement of erythemal UV exposures over 3 to 6 days at a subtropical site without the need to replace the dosimeters because of saturation. The results show that longer-term measurement programs of personal solar UV have been made more feasible with the use of these polysulphone dosimeters with an extended dynamic range compared with unfiltered polysulphone dosimeters. 相似文献
90.
Dr. Cristina Parisi Dr. Mariacristina Failla Dr. Aurore Fraix Dr. Barbara Rolando Dr. Eleonora Gianquinto Prof. Francesca Spyrakis Dr. Elena Gazzano Prof. Chiara Riganti Prof. Loretta Lazzarato Prof. Roberta Fruttero Prof. Alberto Gasco Prof. Salvatore Sortino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(47):11080-11084
Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated. 相似文献