Tunneling magnetic force microscopy

We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording

Long-Lived Double-Barred Galaxies: Critical Mass and Length Scales

A substantial fraction of disk galaxies is double-barred. We analyze the dynamical stability of such nested bar systems by means of Liapunov exponents,by fixing a generic model and varying the inner (secondary) bar mass. We show that there exists a critical mass below which the secondary bar cannot sustain its own orbital structure, and above which it progressively destroys the outer (primary) bar-supporting orbits. In this critical state, a large fraction of the trajectories (regular and chaotic) are aligned with either bar, suggesting the plausibility of long-lived dynamical states when secondary-to-primary bar mass ratio is of the order of a few percent. Qualitatively similar results are obtained by varying the size of the secondary bar, within certain limits, while keeping its mass constant. In both cases, an important role appears to be played by chaotic trajectories which are trapped around (especially) the primary bar for long periods of time.Comment: 7 pages, 1 figure, to be published in Astrophysical Journal Letters (Vol. 595, 9/20/03 issue). Replaced by revised figure and corrected typo

Differential protein expression in maize (Zea mays) in response to insect attack

Maize (Zea mays) is a major food stable in sub-Saharan Africa. However, yields are constrained by insect pests. Insect feeding induces a number of changes in genes encoding different proteins and the plant’s response can either be direct or indirect, or both. In this study, maize plants were infested with two insects with different feeding strategies (Spodoptera littoralis, chewing insect and Busseola fusca, stem borer) to investigate differential protein expression using the Proteomics technique. Infestation of S. littoralis (3rd instar larvae) resulted in 14 spots being up-regulated and 7 being down-regulated. Similarly, infestation of maize with B. fusca (3rd instar larvae) resulted in 12 spots being up-regulated and 9 spots being down-regulated. Interestingly, of those up-regulated only 9 were common to both insects, with only 4 common to both in terms of down regulation. Infestation of maize with S. littoralis resulted in a greater number of spots being up-regulated and less being down-regulated compared to maize infested with B. fusca. Unfortunately, we were unable to identify the proteins represented by these spots.Key words: Busseola fusca, down-regulation, expression, proteomics, Spodoptera littoralis, up-regulation

Thermal Equilibrium as an Initial State for Quantum Computation by NMR

We present a method of using a nuclear magnetic resonance computer to solve the Deutsch-Jozsa problem in which: (1) the number of molecules in the NMR sample is irrelevant to the number of qubits available to an NMR quantum computer, and (2) the initial state is chosen to be the state of thermal equilibrium, thereby avoiding the preparation of pseudopure states and the resulting exponential loss of signal as the number of qubits increases. The algorithm is described along with its experimental implementation using four active qubits. As expected, measured spectra demonstrate a clear distinction between constant and balanced functions.Comment: including 4 figure

Entrenando a la próxima generación de gerentes del riesgo de desastres a través de la investigación y enseñanza en sostenibilidad

Disaster risk management is an integral part of sustainability, and curricula that are focused on sustainability can be broadened to include disaster risk management. The David O’Brien Centre for Sustainable Enterprise at Concordia University researches and teaches disaster risk management through involvement in a collaborative project with the United Nations’ Future Earth network to develop a Sustainable Financial and Economic System Knowledge-to-Action Network (SFES-KAN). The definition of ‘sustainable’ in this context includes disaster risk management. The SFES-KAN aims to align the current financial system with the UN’s sustainable development goals by identifying research gaps and facilitating interdisciplinary research between academics, practitioners, and policymakers to fill those gaps. Our research on such topics as risk management and sustainable investing for the SFES-KAN project has translated into research on disaster risk management and has led to curriculum development on these topics. The goal of our paper is to provide other institutions with examples and strategic information on how to translate such interdisciplinary and solution-oriented sustainability research into research and curricula on disaster risk management.La gestión del riesgo de desastres es una parte integral de la sostenibilidad, y los currículos que se enfocan en la sostenibilidad pueden ser ampliados para incluir la gestión del riesgo de desastres. El David O’Brien Centre for Sustainable Enterprise de Concordia University investiga y enseña la gestión del riesgo de desastres a través de la participación en proyectos colaborativos de la red Future Earth de la Organización de las Naciones Unidas (ONU) para el desarrollo de una Red de “Conocimiento para la Acción” para un Sistema Económico Financiero y Sostenible (SFES-KAN). SFES-KAN busca alinear el sistema financiero actual con los Objetivos de Desarrollo Sostenible de la ONU por medio de la identificación de vacíos en la investigación y la facilitación de una investigación interdisciplinaria entre los académicos, profesionales y legisladores con el fin de llenar dichos vacíos. Nuestra investigación acerca de estos temas de gestión del riesgo e inversiones sostenibles, al igual que para el proyecto SFES-KAN, se ha convertido en investigación sobre gestión del riesgo de desastres y ha conducido al desarrollo curricular de estos temas. El objetivo de este artículo es el de brindar a otras instituciones ejemplos e información estratégica acerca de cómo traducir la investigación de sostenibilidad, interdisciplinaria y orientada a las soluciones, a investigación y currículos sobre gestión del riesgo de desastres

Regional variation in histopathology‐specific incidence of invasive cervical cancer among Peruvian women

ObjectiveTo evaluate patterns of cervical cancer incidence in Peru by examining variation in 2 common histopathologic types, squamous cell carcinoma (SCC) and adenocarcinoma (ADC), and analyzing trends over time.MethodsData on the incidence of invasive cervical cancer between 1984 and 2006 were obtained from 3 population‐based cancer registries in Peru: Lima, Trujillo, and Arequipa. For each registry, data quality assessment was performed, crude and age‐specific incidence was calculated, and time trends were analyzed.ResultsOverall and SCC incidence varied across registries but incidence of ADC did not. Overall and SCC incidence showed significant declines in Trujillo (P 0.05) over time. ADC incidence showed marginally significant increases among women aged 15–29 years in Trujillo (P = 0.10) and modest increases among young women in Lima (P > 0.05).ConclusionPopulation‐based cancer registries were an efficient source of data for evaluating the incidence of cervical cancer once data quality had been established. Geographic and temporal variations in cervical cancer burden were documented in Peru. The trends suggest that cervical ADC is increasing among young women in urban Peru, particularly in Trujillo. We recommend supplementing current Papanicolaou test screening with complementary methods of cervical cancer control, including human papillomavirus (HPV) vaccination and HPV DNA testing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135622/1/ijgo47.pd

The changing pattern of ano-rectal cancer, squamous cell carcinoma of the eye, and Hodgkin’s lymphoma as non-AIDS-defining cancers, by HIV status, in Tanzania over 11 years (2002-2012): a retrospective case-report study

Abstract Background In Tanzania, 5.1% of adults aged 15-49 are infected with HIV. While rates of HIV-related malignancies have declined globally with antiretroviral therapy (ART), including Tanzania, rates of non-AIDS-defining cancers (NADCs) are believed to have increased. Therefore, we determined trends of three NADCs in Tanzania: ano-rectal cancer, squamous cell carcinoma of the eye, and Hodgkin’s lymphoma. Methods This study was conducted at the Ocean Road Cancer Institute (ORCI) in Dar es Salaam. All medical records of patients diagnosed with ano-rectal cancer, squamous cell carcinoma of the eye, and Hodgkin’s lymphoma between 2002 and 2012 were reviewed regarding HIV status, cancer clinical characteristics and management. Analysis was conducted to determine trends and proportions in these three NADCs and patient characteristics. Results We identified 980 NADCs. The relative proportion of these three NADCs at ORCI out of all cancers treated increased from 2.37% in 2002 to a peak of 4.34% in 2009. The prevalence of HIV in patients diagnosed with these NADCs also increased—from 6.67% in 2002 to 20.87% in 2010—and 85% of squamous cell carcinoma of the eye cancer patients with a reported HIV status were HIV-positive. Conclusions The frequency and proportions of these three NADCs in Tanzania have increased over the past 11 years, as has the prevalence of HIV positivity amongst these NADC patients. The current and possibly increasing burden of NADCs in Tanzania and other low- and middle-income countries with high HIV rates should be a focus for future cancer prevention and control and HIV therapy programs.http://deepblue.lib.umich.edu/bitstream/2027.42/111050/1/13027_2014_Article_524.pd

Changing Patterns of lung, liver, and head and neck non-AIDS-defining cancers relative to HIV status in Tanzania between 2002-2014

Abstract Background Tanzania, like other low-income countries, has an increasing cancer burden that remains underestimated. Infection-associated malignancies, particularly HIV-infection, represent a great proportion of cancer burden in Tanzania and throughout Africa. Availability of HIV treatment and improved survival of HIV patients are suggested factors related to increasing prevalence of non-AIDS-defining cancers (NADCs). This study examined patterns of NADCs and proportions of HIV-positivity at the Ocean Road Cancer Institute (ORCI). Methods We reviewed logbooks of all ORCI patients diagnosed and/or treated for lung, liver, and head and neck cancers during 2002–2014. The number of total cancers diagnosed at ORCI during this period was used to calculate proportions of NADCs. We abstracted medical records to obtain demographic and clinical profiles and HIV status information for 1127 patients diagnosed or treated during 2010–2014. Trends in numbers and proportions of NADCs were analyzed using Joinpoint regression. Characteristics of NADC patients were analyzed using multinomial logistic regression. Results NADCs diagnosed at ORCI increased by 33.8% from 2002 to 2014 while the proportion of NADCs relative to all cancers significantly decreased from 6.8% in 2002 to 5.6% in 2014 (APC = -2.74%). Numbers and proportions of lung and liver cancers increased compared to all cancer diagnoses from 2002 to 2014. The number of head and neck cancers increased while decreasing proportionally compared to all cancer diagnoses from 2002 to 2014. Among patients with pathologically confirmed NADCs between 2010 and 2014, HIV prevalence showed a non-statistically significant decrease from 8.1 to 7.1% (APC = -3.77%). Conclusions Absolute numbers of lung, liver, and head and neck cancers increased at ORCI by 1/3 since 2002. Improving survivorship of HIV patients and varying immunodeficiency status may have contributed to the increasing number of NADCs. Total cancer diagnoses nearly doubled during this period, leading to a smaller relative proportion of NADCs diagnosed in 2014 compared to 2002. Late- stage diagnosis and short survival of NADCs included this study may explain possible underestimation and smaller increase in proportion of these particular NADCs compared to other NADCs studied in Tanzania. The slight decrease in proportion of HIV-positive NADC patients during 2010–2014 may suggest increasing patient longevity and more effective HIV management in Tanzania.http://deepblue.lib.umich.edu/bitstream/2027.42/134744/1/13027_2016_Article_106.pd