Emory University

About: Emory University is a education organization based out in Atlanta, Georgia, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 51959 authors who have published 122469 publications receiving 6010698 citations.

Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain

Abstract: Lattice strain is a structural parameter that has been exploited in microelectronic devices with great success, but its role in colloidal nanocrystals is still poorly understood. Here we have developed strain-tunable colloidal nanocrystals by using lattice-mismatched heterostructures that are grown by epitaxial deposition of a compressive shell (e.g., ZnSe or CdS) onto a soft and small nanocrystalline core (e.g., CdTe). This combination of a “squeezed” core and a “stretched” shell causes dramatic changes in both the conduction and valence band energies. As a result, we show that core-shell QDs with standard type-I behavior are converted into type-II nanostructures, leading to spatial separation of electrons and holes, extended excited state lifetimes, and giant spectral shifting. This new class of strain-tunable QDs exhibits narrow light emission with high quantum yield across a broad range of visible and near-infrared wavelengths (500 nm to 1050 nm).

Computed Tomographic Colonography (Virtual Colonoscopy) A Multicenter Comparison With Standard Colonoscopy for Detection of Colorectal Neoplasia

Abstract: ContextConventional colonoscopy is the best available method for detection of colorectal cancer; however, it is invasive and not without risk. Computed tomographic colonography (CTC), also known as virtual colonoscopy, has been reported to be reasonably accurate in the diagnosis of colorectal neoplasia in studies performed at expert centers.ObjectiveTo assess the accuracy of CTC in a large number of participants across multiple centers.Design, Setting, and ParticipantsA nonrandomized, evaluator-blinded, noninferiority study design of 615 participants aged 50 years or older who were referred for routine, clinically indicated colonoscopy in 9 major hospital centers between April 17, 2000, and October 3, 2001. The CTC was performed by using multislice scanners immediately before standard colonoscopy; findings at colonoscopy were reported before and after segmental unblinding to the CTC results.Main Outcome MeasuresThe sensitivity and specificity of CTC and conventional colonoscopy in detecting participants with lesions sized at least 6 mm. Secondary outcomes included detection of all lesions, detection of advanced lesions, possible technical confounders, participant preferences, and evidence for increasing accuracy with experience.ResultsA total of 827 lesions were detected in 308 of 600 participants who underwent both procedures; 104 participants had lesions sized at least 6 mm. The sensitivity of CTC for detecting participants with 1 or more lesions sized at least 6 mm was 39.0% (95% confidence interval [CI], 29.6%-48.4%) and for lesions sized at least 10 mm, it was 55.0% (95% CI, 39.9%-70.0%). These results were significantly lower than those for conventional colonoscopy, with sensitivities of 99.0% (95% CI, 97.1%->99.9%) and 100%, respectively. A total of 496 participants were without any lesion sized at least 6 mm. The specificity of CTC and conventional colonoscopy for detecting participants without any lesion sized at least 6 mm was 90.5% (95% CI, 87.9%-93.1%) and 100%, respectively, and without lesions sized at least 10 mm, 96.0% (95% CI, 94.3%-97.6%) and 100%, respectively. Computed tomographic colonography missed 2 of 8 cancers. The accuracy of CTC varied considerably between centers and did not improve as the study progressed. Participants expressed no clear preference for either technique.ConclusionsComputed tomographic colonography by these methods is not yet ready for widespread clinical application. Techniques and training need to be improved.

Predictability modulates human brain response to reward.

Abstract: Certain classes of stimuli, such as food and drugs, are highly effective in activating reward regions. We show in humans that activity in these regions can be modulated by the predictability of the sequenced delivery of two mildly pleasurable stimuli, orally delivered fruit juice and water. Using functional magnetic resonance imaging, the activity for rewarding stimuli in both the nucleus accumbens and medial orbitofrontal cortex was greatest when the stimuli were unpredictable. Moreover, the subjects' stated preference for either juice or water was not directly correlated with activity in reward regions but instead was correlated with activity in sensorimotor cortex. For pleasurable stimuli, these findings suggest that predictability modulates the response of human reward regions, and subjective preference can be dissociated from this response.

Prognostic impact of histologic subtyping of adult renal epithelial neoplasms: an experience of 405 cases.

Abstract: Just two and a half decades ago adult renal cell neoplasms, i.e., those arising from the renal tubules or collecting duct epithelium, were subdivided into two major subtypes: "clear cell carcinoma" and "granular cell carcinoma." Subsequent detailed morphologic and/or cytogenetic studies have resulted in the recognition of several distinctive subtypes of adult renal epithelial neoplasms, which has led to the promulgation of a refined contemporary histologic classification of these tumors. This study examines the prognostic significance of histologic subtyping in accordance with the new classification in a consecutive series of 405 cases treated at a single institution. Cases were histologically classified into 28 (7%) benign tumors [27 (6.7%) renal oncocytomas, 1 (0.2%) metanephric adenoma] and 377 (93%) malignant tumors [255 (63%) conventional (clear cell) renal cell carcinoma, 75 (18.5%) papillary renal cell carcinoma, 24 (5.9%) chromophobe renal cell carcinoma, and 23 (5.7%) renal cell carcinoma, unclassified]. A total of 25 (6.6%) malignant tumors showed evidence of sarcomatoid change. Kaplan-Meier survival analysis with log-rank test showed histologic type (p = 0.002), Fuhrman's nuclear grade (p = 0.001), TNM stage (p = 0.001), vascular invasion (p = 0.001), and necrosis (p = 0.001) to be significantly associated with disease-specific survival and progression-free survival, based on follow-up of 368 patients (mean 64.5 months, median 56 months). The 5-year disease-specific survival for chromophobe renal cell carcinoma, papillary renal cell carcinoma, conventional (clear cell) renal cell carcinoma, and renal cell carcinoma, unclassified was 100%, 86%, 76%, and 24%, respectively; no patient with a benign tumor diagnosis progressed or died of disease. The 5-year progression-free survival for chromophobe renal cell carcinoma, papillary renal cell carcinoma, conventional (clear cell) renal cell carcinoma, and renal cell carcinoma, unclassified was 94%, 88%, 70%, and 18%, respectively. Malignant tumors with sarcomatoid change had a 35% and 27%, 5-year disease-specific and progression-free survival, respectively. Cox proportional hazards regression analysis showed TNM stage (p = 0.001), nuclear grade (p = 0.01), and necrosis (p = 0.05) to be significant predictors of disease-specific survival. In conclusion, our study shows that the histologic categorization of adult renal epithelial neoplasms performed by routine light microscopic hematoxylin and eosin-based examination in accordance with the contemporary classification scheme has prognostic utility.

Genomic insights into the origin of farming in the ancient Near East

Abstract: We report genome-wide ancient DNA from 44 ancient Near Easterners ranging in time between ~12,000 and 1,400 bc, from Natufian hunter–gatherers to Bronze Age farmers. We show that the earliest populations of the Near East derived around half their ancestry from a ‘Basal Eurasian’ lineage that had little if any Neanderthal admixture and that separated from other non-African lineages before their separation from each other. The first farmers of the southern Levant (Israel and Jordan) and Zagros Mountains (Iran) were strongly genetically differentiated, and each descended from local hunter–gatherers. By the time of the Bronze Age, these two populations and Anatolian-related farmers had mixed with each other and with the hunter–gatherers of Europe to greatly reduce genetic differentiation. The impact of the Near Eastern farmers extended beyond the Near East: farmers related to those of Anatolia spread westward into Europe; farmers related to those of the Levant spread southward into East Africa; farmers related to those of Iran spread northward into the Eurasian steppe; and people related to both the early farmers of Iran and to the pastoralists of the Eurasian steppe spread eastward into South Asia.