879 research outputs found

    Traditional vs Gesture Based UAV Control

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    Abstract. The purpose of this investigation was to assess user preferences for controlling an autonomous system. A comparison using a virtual environment (VE) was made between a joystick based, game controller and a gesture-based system using the leap motion controller. Command functions included basic flight maneuvers and switching between the operator and drone view. Comparisons were made between the control approaches using a representative quadcopter drone. The VE was designed to minimize the cognitive loading and focus on the flight control. It is a physics-based flight simulator built in Unity3D. Participants first spend time familiarizing themselves with the basic controls and vehicle response to command inputs. They then engaged in search missions. Data was gathered on time spent performing tasks, and post test interviews were conducted to uncover user preferences. Results indicate that while th

    A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

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    Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

    Remote control of a robotic hand using a leap sensor

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    This paper presents a low-cost gesture-based remote control of a ro-botic hand. The proposed control architecture is based on a commercial leap motion sensor and an Arduino board, which have been chosen due to their low-cost and user-friendly features. A specific Matlab code has been implemented to collect data from the leap motion sensor and to generate proper instructions to control a robotic hand, which has been 3D print at Sheffield Hallam Univer-sity. Experimental tests have been carried out validate the effectiveness of the proposed remote control for performing various grasping tasks

    Lifting the veil of secrecy: maternal and neonatal outcome of oocyte donation pregnancies in Germany

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    BACKGROUND: In Germany, performing fertility procedures involving oocyte donation is illegal, as stated by the Embryo Protection Law. Nonetheless, in our clinical routine we attend to a steadily rising number of pregnant women, who have sought oocyte donation abroad. Due to the legal circumstances many women opt to keep the origin of their pregnancy a secret. However, studies have shown, that oocyte donation is an independent risk factor for the development of pregnancy complications, such as preeclampsia. OBJECTIVE: The aim of this study is to evaluate maternal and neonatal outcomes of oocyte donation pregnancies in three large obstetric care units in Berlin, Germany. METHODS: We retrospectively analyzed all available medical data on oocyte donation pregnancies at Charité University hospital, Vivantes Hospital Friedrichshain, and Neukoelln in the German capital. RESULTS: We included 115 oocyte donation (OD) pregnancies in the present study. Our data are based on 62 singleton, 44 twin, 7 triplet, and 2 quadruplet oocyte donation pregnancies. According to our data, oocyte donation pregnancies are associated with a high risk of adverse maternal and fetal outcome, i.e., hypertension in pregnancy, preterm delivery, Cesarean section as mode of delivery, and increased peripartum hemorrhage. CONCLUSION: Although oocyte donation is prohibited by German law, many couples go abroad to seek reproductive measures using oocyte donation after former treatment options have failed. OD pregnancies are associated with a high risk of preeclampsia, C-section as mode of delivery, and peripartum hemorrhage. Detailed knowledge of the associated risks is of utmost importance to both the patient and the treating physician and midwife

    Can vital signs recorded in patients' homes aid decision making in emergency care? A Scoping Review

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    Aim: Use of tele-health programs and wearable sensors that allow patients to monitor their own vital signs have been expanded in response to COVID-19. We aimed to explore the utility of patient-held data during presentation as medical emergencies. Methods: We undertook a systematic scoping review of two groups of studies: studies using non-invasive vital sign monitoring in patients with chronic diseases aimed at preventing unscheduled reviews in primary care, hospitalization or emergency department visits and studies using vital sign measurements from wearable sensors for decision making by clinicians on presentation of these patients as emergencies. Only studies that described a comparator or control group were included. Studies limited to inpatient use of devices were excluded. Results: The initial search resulted in 896 references for screening, nine more studies were identified through searches of references. 26 studies fulfilled inclusion and exclusion criteria and were further analyzed. The majority of studies were from telehealth programs of patients with congestive heart failure or Chronic Obstructive Pulmonary Disease. There was limited evidence that patient held data is currently used to risk-stratify the admission or discharge process for medical emergencies. Studies that showed impact on mortality or hospital admission rates measured vital signs at least daily. We identified no interventional study using commercially available sensors in watches or smart phones. Conclusions: Further research is needed to determine utility of patient held monitoring devices to guide management of acute medical emergencies at the patients’ home, on presentation to hospital and after discharge back to the community

    The FLASHForward Facility at DESY

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    The FLASHForward project at DESY is a pioneering plasma-wakefield acceleration experiment that aims to produce, in a few centimetres of ionised hydrogen, beams with energy of order GeV that are of quality sufficient to be used in a free-electron laser. The plasma wave will be driven by high-current density electron beams from the FLASH linear accelerator and will explore both external and internal witness-beam injection techniques. The plasma is created by ionising a gas in a gas cell with a multi-TW laser system, which can also be used to provide optical diagnostics of the plasma and electron beams due to the <30 fs synchronisation between the laser and the driving electron beam. The operation parameters of the experiment are discussed, as well as the scientific program.Comment: 19 pages, 9 figure

    Macrocranium and macrencephaly in neurofibromatosis

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    Data were collected on 52 patients (30 males and 22 females) with neurofibromatosis. Using the volumetric method of Gordon, it was found that 44% of the patients had cranial capacities above the 95th percentile (70% were above the 50th percentile). The presence of intracranial tumors and/or hydrocephalus did not influence skull size. Four patients above the 95th percentile had normal pneumoencephalograms and cerebral angiograms, indicating that the cause of the macrocranium, in some instances at least, is macrencephaly. Volumetric measurement of the sella turcica in 27 of the 52 patients gave results which strongly suggest that idiopathic enlargement of the sella in neurofibromatosis is uncommon, if not rare. Skull films of 26 patients with tuberous sclerosis did not show an increase in cranial capacity similar to that found in neurofibromatosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46770/1/256_2004_Article_BF00347724.pd

    Micro-CT Based Experimental Liver Imaging Using a Nanoparticulate Contrast Agent: A Longitudinal Study in Mice

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    BACKGROUND: Micro-CT imaging of liver disease in mice relies on high soft tissue contrast to detect small lesions like liver metastases. Purpose of this study was to characterize the localization and time course of contrast enhancement of a nanoparticular alkaline earth metal-based contrast agent (VISCOVER ExiTron nano) developed for small animal liver CT imaging. METHODOLOGY: ExiTron nano 6000 and ExiTron nano 12000, formulated for liver/spleen imaging and angiography, respectively, were intravenously injected in C57BL/6J-mice. The distribution and time course of contrast enhancement were analysed by repeated micro-CT up to 6 months. Finally, mice developing liver metastases after intrasplenic injection of colon carcinoma cells underwent longitudinal micro-CT imaging after a single injection of ExiTron nano. PRINCIPAL FINDINGS: After a single injection of ExiTron nano the contrast of liver and spleen peaked after 4-8 hours, lasted up to several months and was tolerated well by all mice. In addition, strong contrast enhancement of abdominal and mediastinal lymph nodes and the adrenal glands was observed. Within the first two hours after injection, particularly ExiTron nano 12000 provided pronounced contrast for imaging of vascular structures. ExiTron nano facilitated detection of liver metastases and provided sufficient contrast for longitudinal observation of tumor development over weeks. CONCLUSIONS: The nanoparticulate contrast agents ExiTron nano 6000 and 12000 provide strong contrast of the liver, spleen, lymph nodes and adrenal glands up to weeks, hereby allowing longitudinal monitoring of pathological processes of these organs in small animals, with ExiTron nano 12000 being particularly optimized for angiography due to its very high initial vessel contrast

    HDAC1 Inactivation Induces Mitotic Defect and Caspase-Independent Autophagic Cell Death in Liver Cancer

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    Histone deacetylases (HDACs) are known to play a central role in the regulation of several cellular properties interlinked with the development and progression of cancer. Recently, HDAC1 has been reported to be overexpressed in hepatocellular carcinoma (HCC), but its biological roles in hepatocarcinogenesis remain to be elucidated. In this study, we demonstrated overexpression of HDAC1 in a subset of human HCCs and liver cancer cell lines. HDAC1 inactivation resulted in regression of tumor cell growth and activation of caspase-independent autophagic cell death, via LC3B-II activation pathway in Hep3B cells. In cell cycle regulation, HDAC1 inactivation selectively induced both p21WAF1/Cip1 and p27Kip1 expressions, and simultaneously suppressed the expression of cyclin D1 and CDK2. Consequently, HDAC1 inactivation led to the hypophosphorylation of pRb in G1/S transition, and thereby inactivated E2F/DP1 transcription activity. In addition, we demonstrated that HDAC1 suppresses p21WAF1/Cip1 transcriptional activity through Sp1-binding sites in the p21WAF1/Cip1 promoter. Furthermore, sustained suppression of HDAC1 attenuated in vitro colony formation and in vivo tumor growth in a mouse xenograft model. Taken together, we suggest the aberrant regulation of HDAC1 in HCC and its epigenetic regulation of gene transcription of autophagy and cell cycle components. Overexpression of HDAC1 may play a pivotal role through the systemic regulation of mitotic effectors in the development of HCC, providing a particularly relevant potential target in cancer therapy
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