The Neural Correlates of Vection: An fMRI Study

Vection is an illusion of visually-induced self-motion in a stationary observer. I used different types of vection stimuli in a functional magnetic resonance imaging (fMRI) study to determine the interaction between cortical visual regions and cortical vestibular regions during vection. My findings suggest that the cingulate sulcus visual area is heavily involved in self-motion processing. The parieto-insular vestibular cortex, showed a significant change in blood oxygenation level dependent signal activity during vection but to a lesser extent than CSv. Behavioural data correlated with the neuroimaging data (in CSv and PIVC) as both show a significant difference when comparing the radial oscillating condition to the radial smooth condition in CSv and PIVC - suggesting a neural correlate of the jitter effect. My results suggest that the brain region of primary importance in the self-motion debate is CSv - a region that has received little attention in the vection literature to date

Null-projectability of Levi-Civita connections

We study the natural property of projectability of a torsion-free connection along a foliation on the underlying manifold, which leads to a projected torsion-free connection on a local leaf space, focusing on projectability of Levi-Civita connections of pseudo-Riemannian metric along foliations tangent to null parallel distributions. For the neutral metric signature and mid-dimensional distributions, Afifi showed in 1954 that projectability of the Levi-Civita connection characterizes, locally, the case of Patterson and Walker's Riemann extension metrics. We extend this correspondence to null parallel distributions of any dimension, introducing a suitable generalization of Riemann extensions.Comment: 15 page

Cooling Optimization Theory- Part I: Optimum Wall Temperature, Coolant Exit Temperature, and the Effect of Wall/Film Properties on Performance

Gas turbine cooling system design is constrained by a maximum allowable wall temperature (dictated by the material and the life requirements of the component), minimum coolant mass flow rate (the requirement to minimize cycle-efficiency cost), and uniform wall temperature (to reduce thermal stresses). These three design requirements form the basis of an iterative design process. The relationship between the requirements has received little discussion in the literature, despite being of interest from both a theoretical and a practical viewpoint. In this paper, we consider the optimum cooling system for parts with both internal and film cooling. We show analytically that the coolant mass flow rate is minimized when the wall temperature is uniform and equal to the maximum allowable wall temperature. Thus, we show that achieving uniform wall temperature achieves minimum coolant flow rate, and vice versa. The purpose is to clarify the interplay between two design requirements that are often discussed separately in the literature. The penalty (in terms of coolant mass flow) associated with cooling nonisothermal components is quantified. We show that a typical high pressure nozzle guide vane (HPNGV) operating isothermally at the maximum allowable wall temperature requires two-thirds the coolant of a typical nonisothermal vane. The optimum coolant exit temperature is also considered. It is shown analytically that the optimum coolant exit temperature depends on the balance between the mean adiabatic film cooling effectiveness, the nondimensional mass flow rate, and the Biot number of the thermal barrier coating (TBC). For the large majority of gas turbine cooling systems (e.g., a typical HPNGV) it is shown that the optimum coolant exit temperature is equal to the local wall temperature at the point of injection. For a small minority of systems (e.g., long effusion cooling systems operating at low mass flow rates), it is shown that the coolant exit temperature should be minimized. An approximation relating the wall/film properties, the nondimensional mass flow, and the overall cooling effectiveness is derived. It is used to estimate the effect of Biot number (TBC and metal), heat transfer coefficient (HTC) ratio, and film properties on the performance of a typical HPNGV and effusion cooling system. In Part II, we show that designs which achieve uniform wall temperature have a particular corresponding internal HTC distribution

“Traditional” charity versus “modern” development : philanthropy and communal boundaries in the Coptic Orthodox Church

Indiana University-Purdue University Indianapolis (IUPUI)Traditional Coptic charity, as I call it, is not just a flawed attempt at humanitarianism, as many believe. It is not just “giving a man a fish” as proponents of “human development” argue. Traditional Coptic charity, as I hope to explain, is an integral part of a larger social system that works together to maintain (and grow slowly) a religious community whose very salvation rests in the practice and transmission of its complex Liturgical body. By merit of its theological peculiarity, and the soteriological significance it gives the practice of sacraments and other religious activities, the Coptic Church effectively hems in the community in perpetuity. This contrasts with the other side of the philanthropic coin—development. Development, which is championed by certain organizations stands as a bulwark of “modernity” in the face of charity’s traditionalism, does not fit into the soteriological orientation of the Church’s Liturgical life. In essence, development’s ultimate goal is to “develop” individuals to the point of “financial independence”—a goal that does not fit into the Church’s communal ethos or exclusively contribute to salvific ends. In recognizing these facts, I began to reevaluate my initial stance on human development as the best way of engaging non-Copts. Overall, this thesis is can be read as a continuation of an ongoing debate between modernity and tradition—and the philanthropic tools they deploy—development and charity

The evolution and heterogeneity of outward foreign direct investment from Latin America

The PhD dissertation investigates the rise of emerging country multinationals (EMNEs), a phenomenon that has opened up a series of research themes and debates. The main debate in this field is the extent to which the theories/frameworks on foreign direct investment (FDI), which have been developed from investigations on multinationals from developed countries, is relevant in explaining outward FDI from EMNEs. This debate is sparked by research suggesting that EMNEs supposedly do not hold the characteristics that are seen as a prerequisite to engaging in FDI. The underlying theme in this PhD is that the field should move away from a one size fit all categorisation of EMNEs, and explore the heterogeneity within EMNEs. Collecting data through various databases, archival articles and annual reports, there was an examination of the internationalisation process of 136 Latin American Multinationals (LAMNEs). The research explores the differences in internationalisation trajectories and global strategies and classifies firms into one of four categories. The four categories that LAMNEs fall into are: Natural-Resource Vertical Integrator, which are firms that are in resource seeking sectors; Accelerated Global, which depict firms that have become global over a very short period of time; Traditional Global, which are EMNEs that have internationalised at the same pace as developed country MNEs and Local Optimisers that only acquire or internationalise to developing countries. The analysis also looks at which decade LAMNEs engaged in FDI, to see if LAMNEs that internationalised during the 1970s and 1980s, during a time when Latin America had a closed economy, was different to LAMNEs that internationalised during the Washington consensus era of the 1990s or to firms that have only just internationalised within the last decade. The findings show that LAMNEs that internationalised before 1990 were more likely to adopt Local Optimiser strategies. However, more LAMNEs that started to internationalise during the 1990s started to adopt Traditional Global strategies, although Local Optimisers were the most prominent strategy. From 2002, there was more prominence of Accelerated Global strategies and a lot more heterogeneity among LAMNEs. Natural-Resource Vertical Integrator LAMNEs, tended to start to internationalisation process during the 1970s/1980s. Despite the rise of EMNEs, and by extension LAMNEs opting to use cross border merger and acquisitions (M&A), there is little research on whether this entry mode has been successful. Contrary to the argument that EMNEs are “internationalising successfully” through this strategy, the findings show that these firms are highly geared and are running less efficiently against their Western competitors. In comparison, LAMNEs internationalising through a more gradual approach, are outperforming their Western competitors on efficiency and are not highly geared- i.e. do not hold a lot of debt. The conclusion of the thesis is the emphasis of moving away from evaluating firms from their country or region of origin, but rather through the global strategy they are using. This will give a more a robust firm level of analysis, and help develop the understanding of EMNEs and international business theory

Management of acute intracerebral haemorrhage – an update

Managing acute intracerebral haemorrhage is a challenging task for physicians. Evidence shows that outcome can be improved with admission to an acute stroke unit and active care, including urgent reversal of anticoagulant effects and, potentially, intensive blood pressure reduction. Nevertheless, many management issues remain controversial, including the use of haemostatic therapy, selection of patients for neurosurgery and neurocritical care, the extent of investigations for underlying causes and the benefit versus risk of restarting antithrombotic therapy after an episode of intracerebral haemorrhage

BOTANICAL AND GENETIC CHARACTERIZATION OF CITRUS MAXIMA (BURM.) MERRILL. F. RUTACEAE

Objective: Total investigation of the macro-and micromorphological features of Citrus maxima (Burm.) Merrill. In addition, DNA fingerprinting in this study was to estimate genetic polymorphism and relationships with another citrus viz: Citrus paradise and Citrus sinensis based on RAPD and ISSR markers.Methods: For the establishment of macro-and micromorphological investigation and genetic estimation, this study presents a total investigation of the macro-and micromorphological features of the roots, stems, leaves, flowers, fruits and seeds of the plants through microscopical investigation of the prepared entire, transverse sections and powdered forms of different organs under study. Furthermore, the DNA of the three plants was extracted from leaf samples and two types of DNA markers RAPD and ISSR were assayed.Results: Macro-and micromorphological features of different organs were investigated. On the other hand Genetic polymorphism and relationships among Citrus maxima, Citrus paradisi and Citrus sinensis was revealed. The highest genetic similarity was between Citrus maxima and Citrus paradisi while the lowest similarity was between Citrus paradisi and Citrus sinensis as revealed by RAPD, ISSR and combined data.Conclusion: For the present study, macro and micro-morphological characters, as well as, DNA fingerprinting can be considered as the identifying parameters for authentication of Citrus maxima (Burm.) Merrill

Indocyanine green fluorescence video angiography reduces vascular injury–related morbidity during micro-neurosurgical clipping of ruptured cerebral aneurysms: a retrospective observational study

Abstract: Background: Specific procedural complications in aneurysm surgery are broadly related to vascular territory compromise and brain/nerve retraction; vascular complications account for about half of this. Intraoperative indocyanine green video angiography (ICG-VA) provides real-time high spatial resolution imaging of the cerebrovascular architecture, allowing immediate quality assurance of aneurysm occlusion and vessel integrity. The aim of this study was to examine whether the routine use of ICG-VA reduced early procedural complications related to vascular compromise or injury during micro-neurosurgical clipping of ruptured cerebral aneurysms. Methods: Retrospective comparative observational study of 412 adult good-grade (WFNS 1 or 2) SAH patients who had undergone microsurgical clipping without (n = 200, 2001–2004) or with (n = 212, 2009–2015) ICG-VA in a high-volume neurosurgical centre. Results: The ICG-VA group had a significantly lower incidence of procedural vascular complications (7/212; 3.3%) compared with the non-ICG-VA group (19/200; 9.5%) (Fisher’s exact test p = 0.0137). Conclusions: ICG-VA is a straightforward, easy-to-use, intraoperative adjunct which significantly reduces avoidable ‘technical error’ related morbidity

Volumetric growth rates of meningioma and its correlation with histological diagnosis and clinical outcome: a systematic review.

INTRODUCTION: Tumour growth has been used to successfully predict progression-free survival in low-grade glioma. This systematic review sought to establish the evidence base regarding the correlation of volumetric growth rates with histological diagnosis and potential to predict clinical outcome in patients with meningioma. METHODS: This systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Databases were searched for full text English articles analysing volumetric growth rates in patients with a meningioma. RESULTS: Four retrospective cohort studies were accepted, demonstrating limited evidence of significantly different tumour doubling rates and shapes of growth curves between benign and atypical meningiomas. Heterogeneity of patient characteristics and timing of volumetric assessment, both pre- and post-operatively, limited pooled analysis of the data. No studies performed statistical analysis to demonstrate the clinical utility of growth rates in predicting clinical outcome. CONCLUSION: This systematic review provides limited evidence in support of the use of volumetric growth rates in meningioma to predict histological diagnosis and clinical outcome to guide future monitoring and treatment

A systematic review and meta-analysis of the association between cyproterone acetate and intracranial meningiomas.

The influence of exposure to hormonal treatments, particularly cyproterone acetate (CPA), has been posited to contribute to the growth of meningiomas. Given the widespread use of CPA, this systematic review and meta-analysis attempted to assess real-world evidence of the association between CPA and the occurrence of intracranial meningiomas. Systematic searches of Ovid MEDLINE, Embase and Cochrane Controlled Register of Controlled Trials, were performed from database inception to 18th December 2021. Four retrospective observational studies reporting 8,132,348 patients were included in the meta-analysis. There was a total of 165,988 subjects with usage of CPA. The age of patients at meningioma diagnosis was generally above 45 years in all studies. The dosage of CPA taken by the exposed group (n = 165,988) was specified in three of the four included studies. All studies that analyzed high versus low dose CPA found a significant association between high dose CPA usage and increased risk of meningioma. When high and low dose patients were grouped together, there was no statistically significant increase in risk of meningioma associated with use of CPA (RR = 3.78 [95% CI 0.31-46.39], p = 0.190). Usage of CPA is associated with increased risk of meningioma at high doses but not when low doses are also included. Routine screening and meningioma surveillance by brain MRI offered to patients prescribed with CPA is likely a reasonable clinical consideration if given at high doses for long periods of time. Our findings highlight the need for further research on this topic