Complex refractive index of non-spherical particles in the vis-NIR region - application to Bacillus Subtilis spores

A method is presented for the estimation of optical constants in the ultraviolet-visible-near-infrared (UVVis-NIR) region of nonspherical particles in a suspension at concentrations where multiple scattering issignificant. The optical constants are obtained by an inversion technique using the adding-doubling method to solve the radiative transfer equation in combination with the single scattering theories for modelling scattering by nonspherical particles. Two methods for describing scattering by single scatteringare considered: the T-matrix method and the approximate but computationally simpler Rayleigh-Gans-Debye (RGD) approximation. The method is then applied to obtain the optical constants of Bacillussubtilis spores in the wavelength region 400-1200 nm. It is found that the optical constants obtained using the RGD approximation matches those obtained using the T-matrix method to within experimental error

Hippocampal and Anterior Cingulate Cortex Volumes in Amnestic and Non-Amnestic Mild Cognitive Impairment

Mild Cognitive Impairment (MCI) is a syndrome thought to fall between cognitively normal aging and dementia. Although much research has investigated the structural neuroimaging correlates of amnestic MCI, little research has been done on the imaging correlates of non-amnestic MCI. Even less research has examined the anterior cingulate cortex (ACC), a region important in executive functions (EFs), in these patients. This study attempted to address this gap by examining hippocampal and ACC volumes among amnestic and non-amnestic MCI patients and cognitively normal controls. Those with amnestic MCI were expected to have smaller hippocampal volumes than controls and those with non-amnestic MCI, while those with non-amnestic MCI were expected to have smaller ACC volumes than controls or those with amnestic MCI. Fifty-seven participants, 21 cognitively normal controls, 20 with amnestic MCI, and 16 with non-amnestic MCI, were recruited. Contrary to hypotheses, mixed-model analyses of variance revealed no significant differences among the diagnostic groups in ACC or hippocampal volumes. These results suggest that the ACC is not involved in MCI or that it is affected only in later disease stages. The executive dysfunction seen in some cases of non-amnestic MCI may be due to atrophy in other brain regions associated with EF or may be due to white matter changes in these regions. However, the study\u27s small, highly educated sample and the possibility that amnestic MCI patients also exhibited executive dysfunction may also have impacted results. Future research should longitudinally examine MCI patients with and without executive dysfunction to determine the role of the ACC and other brain regions involved in EF and should also investigate the correlation between neuropsychological test scores and volumes in these brain regions

Vascular Risk, Functional Connectivity, and Episodic Memory in Older Adults

Resting-state functional magnetic resonance imaging and functional connectivity (FC) analyses are used to explore functional brain networks underlying a diverse array of abilities. Functional networks are composed of regions throughout the brain whose activity is closely linked to form a coherent network. One functional network, the default mode network (DMN), is thought to subserve self-referential thought and autobiographical memory. DMN regions include the ventromedial prefrontal cortex, inferior parietal lobe, hippocampus, and the primary hub of this network, the posterior cingulate cortex (PCC). For reasons yet unknown, DMN FC declines in aging, which is associated with memory impairment. Vascular risk may be an important contributor to age-related DMN disruption through its effects on gray and white matter integrity. The present study examined relationships among vascular risk, DMN FC, and episodic memory in older adults using FC analyses and structural equation modeling. Several regions found to be functionally related to the PCC were those identified in prior research on the DMN, but also included areas not typically implicated in the DMN, such as the cerebellum and basal ganglia. Stronger FC between the PCC and parahippocampal gyrus predicted better memory performance, confirming the importance of medial temporal lobe structures for memory. FC between the PCC and several other areas, such as the cerebellum, basal ganglia, and limbic regions, also predicted memory performance, suggesting the importance of executive functioning and emotion for memory in aging. Correlations between FC and vascular risk were found in the basal ganglia, cerebellum, and inferior temporal gyrus, suggesting vascular risk may modify associations between the DMN and cortical and subcortical regions. Finally, a mediational model was tested in which DMN FC mediated the relationship between vascular risk and memory. This was compared to an alternative model with depressive symptoms as a mediator. Vascular risk was unrelated to memory and DMN FC in all models, while stronger DMN FC predicted poorer memory performance. Neither DMN FC nor depressive symptoms acted as mediators. The impact of vascular risk on the DMN in aging should be further explored using a comprehensive multimethod approach, along with other potential causes of age-related DMN disruption

Increased incidence of thyroid cancer among world trade center first responders: A descriptive epidemiological assessment

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. An increased incidence of thyroid cancer among 9/11 rescue workers has been reported, the etiology of which remains unclear but which may, at least partly, be the result of the increased medical surveillance this group undergoes. This study aimed to investigate thyroid cancer in World Trade Center (WTC) responders by looking at the demographic data and questionnaire responses of thyroid cancer cases from the Mount Sinai WTC Health Program (WTCHP). WTCHP thyroid cancer tumors were of a similar size (p = 0.4), and were diagnosed at a similar age (p = 0.2) compared to a subset of thyroid cancer cases treated at Mount Sinai without WTC exposure. These results do not support the surveillance bias hypothesis, under which smaller tumors are expected to be diagnosed at earlier ages. WTCHP thyroid cancer cases also reported a past history of radiation exposure and a family history of thyroid conditions at lower rates than expected, with higher than expected rates of previous cancer diagnoses, family histories of other cancers, and high Body Mass Indexes (BMIs). Further research is needed to better understand the underlying risk factors that may play a role in the development of thyroid cancer in this group

Primary squamous cell carcinoma of the liver: an unexpected pathological finding

Abstract Background Primary squamous cell carcinoma of the liver is a very rare cancer requiring a complete diagnostic investigation, as it presents some differences from other primary hepatic malignancies. We describe the case of an elderly patient with primitive squamous cell carcinoma of the liver treated by percutaneous microwave ablation and transarterial chemoembolization. Case presentation Although the pathogenesis remains uncertain, a possible transformation of the biliary epithelium caused by chronic inflammation or metaplasia and subsequent malignant transformation of preexisting benign hepatic cysts has been suggested. A critical review of the existing literature was performed by focusing on the pathogenesis, clinical presentation, and the suggested therapeutic strategies. Conclusion A multidisciplinary approach is needed to face rare hepatic malignancies where there are no clear guidelines

Measurement of Optical Properties of Small Particles

We have measured the optical constants of montmorillonite and the separated coats and cores of B. subtilis spores over the wavelength interval from 200 nm to 2500 nm. The optical constants of kaolin were obtained over the wavelength interval from 130 nm to 2500 nm. Our results are applicable to the development of systems for detection of airborne biological contaminants. Future work will include measurement of the optical constants of B. cereus spores, B. sub tilts vegetative cells, egg albumin, illite, and a mixture (by weight) of one third kaolin, one third montmorillonite, and one third illite