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Femtosecond electron diffraction is used to directly resolve the atomic motions involved in the ring closing reaction induced in a photochromic single crystal. The measurements were performed using our newly developed setup capable of delivering sub-500 fs electron bunches containing 106 electrons per pulse. Theoretical calculations were also performed.

Recent international consensus guidelines propose that cystic pancreatic tumors less than 3 cm in size in asymptomatic patients with no radiographic features concerning for malignancy are safe to observe; however, there is little published data to support this recommendation. The purpose of this study was to determine the prevalence of malignancy in this group of patients using pancreatic resection databases from five high-volume pancreatic centers to assess the appropriateness of these guidelines. All pancreatic resections performed for cystic neoplasms < or =3 cm in size were evaluated over the time period of 1998-2006. One hundred sixty-six cases were identified, and the clinical, radiographic, and pathological data were reviewed. The correlation with age, gender, and symptoms (abdominal pain, nausea and vomiting, jaundice, presence of pancreatitis, unexplained weight loss, and anorexia), radiographic features suggestive of malignancy by either computed tomography, magnetic resonance imaging, or endoscopic ultrasound (presence of solid component, lymphadenopathy, or dilated main pancreatic duct or common bile duct), and the presence of malignancy was assessed using univariate and multivariate analysis. Among the 166 pancreatic resections for cystic pancreatic tumors < or =3 cm, 135 cases were benign [38 serous cystadenomas, 35 mucinous cystic neoplasms, 60 intraductal papillary mucinous neoplasms (IPMN), 1 cystic papillary tumor, and 1 cystic islet cell tumor], whereas 31 cases were malignant (14 mucinous cystic adenocarcinomas and 13 invasive carcinomas and 4 in situ carcinomas arising in the setting of IPMN). A greater incidence of cystic neoplasms was seen in female patients (99/166, 60%). Gender was a predictor of malignant pathology, with male patients having a higher incidence of malignancy (19/67, 28%) compared to female patients (12/99, 12%; p < 0.02). Older age was associated with malignancy (mean age 67 years in patients with malignant disease vs 62 years in patients with benign lesions (p < 0.05). A majority of the patients with malignancy were symptomatic (28/31, 90%). Symptoms that correlated with malignancy included jaundice (p < 0.001), weight loss (p < 0.003), and anorexia (p < 0.05). Radiographic features that correlated with malignancy were presence of a solid component (p < 0.0001), main pancreatic duct dilation (p = 0.002), common bile duct dilation (p < 0.001), and lymphadenopathy (p < 0.002). Twenty-seven of 31(87%) patients with malignant lesions had at least one radiographic feature concerning for malignancy. Forty-five patients (27%) were identified as having asymptomatic cystic neoplasms. All but three (6.6%) of the patients in this group had benign disease. Of the patients that had no symptoms and no radiographic features, 1 out of 30 (3.3%) had malignancy (carcinoma in situ arising in a side branch IPMN). Malignancy in cystic neoplasms < or =3 cm in size was associated with older age, male gender, presence of symptoms (jaundice, weight loss, and anorexia), and presence of concerning radiographic features (solid component, main pancreatic duct dilation, common bile duct dilation, and lymphadenopathy). Among asymptomatic patients that displayed no discernable radiographic features suggestive of malignancy who underwent resection, the incidence of occult malignancy was 3.3%. This study suggests that a group of patients with small cystic pancreatic neoplasms who have low risk of malignancy can be identified, and selective resection of these lesions may be appropriate. [ABSTRACT FROM AUTHOR]

Objective: This study was designed to identify factors that influence primary care physicians' willingness to perform flexible sigmoidoscopy.Measurements: Using a mailed questionnaire, we surveyed all 161 primary care physicians participating in a large health care system. We obtained information on training, current practice patterns, beliefs about screening for colorectal cancer, and the influence of various factors on their decision whether or not to perform flexible sigmoidoscopy in practice.Main Results: Of the 131 physicians included in the analysis, 68 (52%) reported training in flexible sigmoidoscopy, of whom 36 (53%) were currently performing flexible sigmoidoscopy in practice. Time required to perform flexible sigmoidoscopy, availability of adequately trained staff, and availability of flexible sigmoidoscopy services provided by other clinicians were identified most often as reasons not to perform the procedure in practice. Male physicians were more likely than female physicians to report either performing flexible sigmoidoscopy or desiring to train to perform flexible sigmoidoscopy (odds ratio 2.61; 95% confidence interval 1.10, 6.23). This observed difference appears to be mediated through different weighting of decision criteria by male and female physicians.Conclusions: Approximately half of these primary care physicians trained in flexible sigmoidoscopy chose not to perform this procedure in practice. Self-perceived inefficiency in performing office-based flexible sigmoidoscopy deterred many of these physicians from providing this service for their patients. [ABSTRACT FROM AUTHOR]

The hemolymph fraction containing juvenile hormone binding protein (JHBP) has been shown to generate multiple molecular forms of JHBP under given experimental conditions. They differ in affinity toward ionic exchanger and in pI values, but exhibit unchanged Stokes radius, sedimentation coefficient and K for the hormone. This process is inhibited by phenylmethylsulfonyl fluoride or high ionic strength and presumably reflects an initial step of proteolytic modification of the JHBP. [ABSTRACT FROM AUTHOR]