Diatoms have long been known to be photosensitive, altering the direction of their movement in response to changes in ambient light conditions detected at the tips of the cells. In order to better understand the light conditions responsible for triggering positive photophobic (out-of-light) and negative photophobic (into-light) responses of diatoms, cells from three species of diatoms, Craticula cuspidata (Kützing) D.G. Mann, Stauroneis phoenicenteron (Nitzsch) Ehrenberg, and Pinnularia viridis (Nitzsch) Ehrenberg, were irradiated at their leading or trailing ends during cell movement. The response times for direction changes when cells were irradiated at various irradiance levels and wavelengths were measured to determine the quality of light responsible for eliciting cell direction changes in each of the three species. All three species displayed strong out-of-light responses at the highest irradiances measured. Craticula cuspidata cells displayed negative photophobic sensitivity (into-light) responses in moderate level blue light, while S. phoenicenteron cells showed into-light responses with low-level red light. Pinnularia viridis cells showed less responsiveness to blue and green light than the other two species, and almost no sensitivity to red light. By re-irradiating cells a second time after a previous leading or trailing end irradiation, we observed a 2-3 fold (leading) or 3-8 fold (trailing) motility repression, caused by the initial light exposures, which lasted for approximately 30-60 sec. Irradiating the cells multiple times, upon each direction change, indicated some degree of habituation to irradiation over time. Multiple consecutive irradiations of the trailing end of diatoms resulted in strong repression of any direction change, with cells continuing to move in the same direction for up to 20 min; this repression became reduced as the interval time between trailing-end irradiations increased. These results suggest that diatoms display species-specific physiological responses to light irradiations that may help them to appropriately respond to ambient light conditions, and better organize and succeed within larger algal or multi-species diatom assemblages.

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INTRODUCTION: The objective of this study was to assess smoking cessation and reduction patterns among pregnant smokers. One in ten women in the United States will continue to smoke during their pregnancy. Smoking continuation during pregnancy is one of the most preventable causes of negative health outcomes for both the mother and baby. METHODS: We used data from a prior study of 468 pregnant patients. In this study, participants self-identified as tobacco smokers during the visit. Data was abstracted from all obstetrics visit(s) to assess cessation or continuation of smoking. For patients who reported quitting, we noted gestational age when quit was first documented. We also assessed whether cessation was sustained through documentation in subsequent progress notes. We performed descriptive statistics using SPSS. RESULTS: From 468 total study patients, 167 patients (36%) admitted to smoking tobacco during the first obstetric visits. Fifty-three (31.7%) patients quit during their pregnancy. Of these 53 patients, 41.5% quit during the first trimester, 47.2% during the second trimester, and 11.3% during the third trimester. Additionally, 11 of the 53 (20.8%) had remained quit at their postpartum visit where 4 of the 53 (7.5%) claimed to have started smoking again postpartum. The remaining 38 (72%) either did not come to their postpartum visit or were not asked about their smoking status at the visit. CONCLUSION: Less than a third of pregnant smokers quit smoking during their pregnancy. Those that quit were more likely to do so earlier in the pregnancy. Efforts for smoking cessation should target early pregnancy visits.