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J.I. Crabtree 《Journal of The Franklin Institute》1918,186(3):371-372
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It is very difficult, if not impossible, to remove the last traces of hypo from photographic papers by any known procedure of washing. The sulfur in the residual hypo ultimately, and especially under abnormal conditions of temperature and humidity, combines with the silver image to form yellowish brown silver sulfide. This phenomenon is known as sulfiding or “fading” of the image. The various factors which affect the rate of fading of images and the washing out of hypo from films and papers are outlined.Chemical methods of hypo elimination have been proposed from time to time but the majority of these have not been satisfactory because they tend to leave substances such as thionates in the photographic material, which are equally as difficult to wash out as hypo and which also tend to sulfide or fade the silver image. A new hypo eliminator is recommended consisting of two volatile chemicals, hydrogen peroxide and ammonia. This eliminator oxidizes the hypo to sodium sulfate, which is inert and soluble in water, while any excess eliminator evaporates on drying.Two formulas and treatments are proposed: (1) Complete elimination of hypo for use by the professional, advanced amateur, and photofinisher who demand the highest standard of photographic quality in their prints.(2) Almost complete elimination of hypo (less than o.oi milligram per square inch).Since the conditions to which prints will be subjected are rarely known in advance, use of the “complete elimination treatment” is advised in all cases. 相似文献
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J.I. Crabtree 《Journal of The Franklin Institute》1925,199(1):110-111
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This study compared the performance of 45 first graders in partial French immersion, partial Hebrew immersion, and traditional English programs on measures of linguistic analysis ability and early reading skills in English. A modified version of the Auditory Analysis Test (Rosner and Simon, 1971) established that both French and Hebrew immersion children were more proficient than their English program peers at explicity analyzing the internal structure of spoken words. Subjects in the Hebrew program read non-words more successfully than either of the other two groups, and read orthographically regular real words better than the control subjects. These results suggest that second language learning, even in a partial immersion setting, enhances linguistic awareness. The potential implications for reading skill acquisition are discussed.This research was funded by Grant A2008 from the Natural Sciences and Engineering Research Council of Canada. 相似文献
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This paper explores the perceptions and experiences of women academics in the UK, participating in a small-scale qualitative study exploring career progression and encountered institutional obstacles. The accounts are considered in terms of both disadvantageous institutional strategies and interpersonal ones governing day-to-day working relationships. The findings contribute to a growing body of international research on gender constructions in the academy, where both inhibiting and exclusionary barriers are examined in focus group discussions (FGDs) in terms of gendered constructions that are perceived to impact upon the career opportunities of women academics. Analysis of data encouraged the employment of a ludic construction in this critical exploration of games playing and ‘gamesmanship’ (a masculinised term); these being themes raised in the FGDs as representing blocks and challenges to women’s academic careers. 相似文献
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CRABTREE Vincent P. AZORIN-PERIS Vincent ECHIADIS Angelos SMITH Peter R. 《浙江大学学报(A卷英文版)》2007,8(6):916-920
Objective: To study the regulation of blood pulse volume via photoplethysmography (PPG) signal detected from toe, while the lower limb is passively raised in different height positions. Methods: Use a modified non-invasive PPG technique to detect the blood pulse signal on toe with infrared (IR) photo sensor. A protocol consisting of two postures, i.e., supine and 45° reclining, was designed to conduct laboratory trial in this study. During the period of performing the protocol of these postures, the lower limb was passively raised from the heights of 10 cm to 60 cm randomly and individually with sponge blocks underneath the foot. Results: In the supine posture, the higher the foot was passively raised, the more the blood PPG signal decreased. In the 45° reclining posture, the blood PPG signal increased at the beginning and then decreased in the foot height position from 10 cm to 60 cm. In both postures the normalized AC signal changes significantly while the normalized DC signal changes little. Conclusion: The toe PPG signals can obviously indicate the regulated blood volume change with the designated postural procedures due to the heart level position. 相似文献