Stopping Periods Research Articles

Freezing of gait assessment with inertial measurement units and deep learning: effect of tasks, medication states, and stops

BackgroundFreezing of gait (FOG) is an episodic and highly disabling symptom of Parkinson’s Disease (PD). Traditionally, FOG assessment relies on time-consuming visual inspection of camera footage. Therefore, previous studies have proposed portable and automated solutions to annotate FOG. However, automated FOG assessment is challenging due to gait variability caused by medication effects and varying FOG-provoking tasks. Moreover, whether automated approaches can differentiate FOG from typical everyday movements, such as volitional stops, remains to be determined. To address these questions, we evaluated an automated FOG assessment model with deep learning (DL) based on inertial measurement units (IMUs). We assessed its performance trained on all standardized FOG-provoking tasks and medication states, as well as on specific tasks and medication states. Furthermore, we examined the effect of adding stopping periods on FOG detection performance.MethodsTwelve PD patients with self-reported FOG (mean age 69.33 ± 6.02 years) completed a FOG-provoking protocol, including timed-up-and-go and 360-degree turning-in-place tasks in On/Off dopaminergic medication states with/without volitional stopping. IMUs were attached to the pelvis and both sides of the tibia and talus. A temporal convolutional network (TCN) was used to detect FOG episodes. FOG severity was quantified by the percentage of time frozen (%TF) and the number of freezing episodes (#FOG). The agreement between the model-generated outcomes and the gold standard experts’ video annotation was assessed by the intra-class correlation coefficient (ICC).ResultsFor FOG assessment in trials without stopping, the agreement of our model was strong (ICC (%TF) = 0.92 [0.68, 0.98]; ICC(#FOG) = 0.95 [0.72, 0.99]). Models trained on a specific FOG-provoking task could not generalize to unseen tasks, while models trained on a specific medication state could generalize to unseen states. For assessment in trials with stopping, the agreement of our model was moderately strong (ICC (%TF) = 0.95 [0.73, 0.99]; ICC (#FOG) = 0.79 [0.46, 0.94]), but only when stopping was included in the training data.ConclusionA TCN trained on IMU signals allows valid FOG assessment in trials with/without stops containing different medication states and FOG-provoking tasks. These results are encouraging and enable future work investigating automated FOG assessment during everyday life.

Migrating eagles stopping in the Sahara Desert: Aberrant behaviour or foraging strategy?

AbstractThe Sahara Desert is one of the major ecological barriers of the Palearctic‐Africa bird migration system. We analysed the behaviour of GPS‐tagged booted eagles (Aquila pennata) breeding in Spain and wintering in Tropical Africa, focusing on the Sahara crossing. We searched for anomalous track segments recorded during the desert crossing, finding that non‐directional and/or slow movements occur in 35% of the migratory journeys and last up to 31 days (average: 5.9). The analyses show that this behaviour is not triggered by adverse weather conditions, and is shown especially by females during spring. The length of the stopping periods affects the arrival date to the breeding grounds only in males, which means that females buffer the potential delay with an earlier migration start, suggesting that this behaviour is followed deliberately. These wandering movements occur in hyper‐arid areas without vegetation cover. A similar behaviour has not been previously recorded in any other trans‐Saharan raptor and is probably related to the ability of booted eagles to take advantage of food resources unexploited by other predators, such as migratory songbirds stopping in the desert during the day, and migratory locusts. If confirmed by further research involving higher resolution tracking and field observations, our findings may show a new way of combining foraging and migration, without a well‐defined directed trajectory, nor stopping in a restricted spot, but instead wandering over wide areas.

Dataset creation and selection methods with a wire drive flexible manipulator for vision-based reconstruction

In order to improve spatial awareness for future investigations of reactor No. 2 at the Fukushima nuclear power plant, it is necessary first to acquire the environment model through reconstruction. To gather images for this task, we have developed a flexible, compact, and lightweight manipulator called the Bundled Wire Drive robot. However, due to mechanism’ shortcomings, the feasibility of using this robot is limited by potential degradations of image quality, including odometry deviation and motion blur. Based on the motion characteristics of the robot, we have proposed a dataset creation and selection method to mitigate the impact of these degradations. The effectiveness of this method was verified through experiments with a hardware prototype robot, which demonstrates that it is possible to avoid the influence of matched joint movement deviation by using overlapping simple trajectories; and pre-filtering out blurry images, which usually concentrate on the beginning and stopping periods. Additionally, we conducted a robustness study of mainstream reconstruction methods under limited illumination conditions to quantitively study the performance degradation in a more realistic environment.

Association of Medication Treatment for Opioid Use Disorder With Suicide Mortality.

Understanding the effectiveness of medication treatment for opioid use disorder to decrease the risk of suicide mortality may inform clinical and policy decisions. The authors sought to describe the effect of medications for opioid use disorder (MOUD) on risk of suicide mortality. This was a retrospective cohort study in Department of Veterans Affairs (VA) patients from 2003 to 2017. The authors linked three data sources: the VA Corporate Data Warehouse, Centers for Medicare and Medicaid Services Claims Data, and the VA-Department of Defense Mortality Data Repository. The exposure of interest was MOUD, including starting periods (first 14 days on treatment), stopping periods (first 14 days off treatment), stable time on treatment, and stable time off treatment (reference category). The main outcome measures included suicide mortality, external-cause mortality, and all-cause mortality in the 5 years following initiation of MOUD. Over 60,000 VA patients received MOUD. Patients were typically male (92.8%) and their mean age was 46.5 years (SD=13.1). After adjusting for demographic characteristics, mental health and physical health conditions, and health care utilization, the adjusted hazard ratio during stable MOUD was 0.45 (95% CI=0.32, 0.63) for suicide mortality, 0.35 (95% CI=0.31, 0.40) for external-cause mortality, and 0.34 (95% CI=0.31, 0.37) for all-cause mortality. MOUD starting periods were associated with an adjusted hazard ratio for suicide mortality of 0.55 (95% CI=0.25, 1.21), and MOUD stopping periods were associated with an adjusted hazard ratio for suicide mortality of 1.38 (95% CI=0.82, 2.34). Treatment with MOUD was associated with a substantial reduction in suicide mortality as well external causes of mortality and all-cause mortality.

The design of a Bayesian adaptive clinical trial of tranexamic acid in severely injured children

BackgroundTrauma is the leading cause of death and disability in children in the USA. Tranexamic acid (TXA) reduces the blood transfusion requirements in adults and children during surgery. Several studies have evaluated TXA in adults with hemorrhagic trauma, but no randomized controlled trials have occurred in children with trauma. We propose a Bayesian adaptive clinical trial to investigate TXA in children with brain and/or torso hemorrhagic trauma.Methods/designWe designed a double-blind, Bayesian adaptive clinical trial that will enroll up to 2000 patients. We extend the traditional Emax dose-response model to incorporate a hierarchical structure so multiple doses of TXA can be evaluated in different injury populations (isolated head injury, isolated torso injury, or both head and torso injury). Up to 3 doses of TXA (15 mg/kg, 30 mg/kg, and 45 mg/kg bolus doses) will be compared to placebo. Equal allocation between placebo, 15 mg/kg, and 30 mg/kg will be used for an initial period within each injury group. Depending on the dose-response curve, the 45 mg/kg arm may open in an injury group if there is a trend towards increasing efficacy based on the observed relationship using the data from the lower doses. Response-adaptive randomization allows each injury group to differ in allocation proportions of TXA so an optimal dose can be identified for each injury group. Frequent interim stopping periods are included to evaluate efficacy and futility. The statistical design is evaluated through extensive simulations to determine the operating characteristics in several plausible scenarios. This trial achieves adequate power in each injury group.DiscussionThis trial design evaluating TXA in pediatric hemorrhagic trauma allows for three separate injury populations to be analyzed and compared within a single study framework. Individual conclusions regarding optimal dosing of TXA can be made within each injury group. Identifying the optimal dose of TXA, if any, for various injury types in childhood may reduce death and disability.

Models for COVID-19 Daily Confirmed Cases in Different Countries

In this paper, daily confirmed cases of COVID-19 in different countries are modelled using different mathematical regression models. The curve fitting is used as a prediction tool for modeling both past and upcoming coronavirus waves. According to virus spreading and average annual temperatures, countries under study are classified into three main categories. First category, the first wave of the coronavirus takes about two-year seasons (about 180 days) to complete a viral cycle. Second category, the first wave of the coronavirus takes about one-year season (about 90 days) to complete the first viral cycle with higher virus spreading rate. These countries take stopping periods with low virus spreading rate. Third category, countries that take the highest virus spreading rate and the viral cycle complete without stopping periods. Finally, predictions of different upcoming scenarios are made and compared with actual current smoothed daily confirmed cases in these countries.

Female Military Officers Report a Desire for Menstrual Suppression During Military Training.

Service women face female-specific challenges that present physiological and logistical burdens and may impact readiness. The stress of training can change menstrual patterns and symptoms, and limited access to hygienic, private facilities can hinder menstrual management. Therefore, suppressing menses with continuous hormonal contraception may be of interest. The 9-item "Military Women's Attitudes Toward Menstrual Suppression." questionnaire was administered to female officers upon entry (baseline) and graduation (post) from a 6-month secondary training course. Respondents rated their attitudes about menstruation and the stress of training, the desire for menstrual suppression, and the logistical burden of menstruation on a 1 (strongly agree) through 5 (strongly disagree) scale. Wilcoxon Signed Rank Tests determined changes in the distribution of responses from baseline to post. Female officers (n = 108) completed baseline and post questionnaires (age 25.2 ± 0.3 years). At baseline, the majority disagreed/strongly disagreed that the stress of training "makes periods worse than usual" (n = 77, 71%), "increases menstrual symptoms and bleeding" (n = 77, 71%), or "magnifies premenstrual syndrome" (PMS; n = 69, 64%). Although 50% (n = 54) agreed/strongly agreed that "stopping periods while women are training is a good idea," 37% (n = 40) disagreed/strongly disagreed. The majority agreed/strongly agreed that menstrual suppression would prevent "the worry about menstrual supplies" (n = 75, 70%) and "the inconvenience of having a period during training" (n = 69, 64%). Many agreed/strongly agreed that it is difficult to deal with periods during training because "there is no privacy" (n = 52, 48%), "the inability to find adequate facilities" (n = 70, 65%), and "the lack of opportunity to use adequate facilities" (n = 52, 48%). Opinions remained largely consistent from baseline to post. The desire for menstrual suppression among service women during training is high. Military health care providers should be prepared to counsel service women about strategies to manage menstruation, including the efficacy of continuous hormonal contraception for menstrual suppression. Future studies investigating benefits or risks of continuous hormonal contraception for menstrual suppression in service women should inform the clinical recommendations.

Utilization of solar energy and climate control systems for enhancing poultry houses productivity

Poultry housing is chosen for the development because it has the highest portion of energy consumption. Solar energy and climate control systems are utilized for producing the highest productivity and conversion rate poultry housing comparing with the conventional methods. Thermal analysis of solar heating unit and photovoltaic is conducted to find out their thermal efficiencies. Experiments are conducted under the following conditions using three power operating systems [flat-plate solar collector + electricity (power operating), flat plate solar collector + photovoltaic and conventional system (depending on only electricity)] and fan stopping periods (2, 5 and 8 min). The poultry house performance was evaluated in terms of relative humidity, ammonia concentration, poultry production, feed conversion rate, required power and production cost. Based on the theoretical analysis, the efficiency of the solar heating system and photovoltaic cells was about 71.6% and 12.5%, respectively. Experimental results reveal that the optimum conditions for enhancing the poultry production (2.29 kg) with conversion rate (1.45 kg feed per kg gain), ammonia concentration at the fifth week (13.65 ppm), production cost (1.12 US $/kg) are achieved by using power operating system of flat-plate solar collector integrated with photovoltaic under 2 min fan stopping periods.

Dynamic analysis of a concentrating photovoltaic/concentrating solar power (CPV/CSP) hybrid system

Concentrating photovoltaic/concentrating solar power (CPV/CSP) systems suffer from varying irradiation and extreme working conditions. In this study, a dynamic physical model is developed for the CPV/CSP hybrid system to analyze the dynamic responses of several key parameters, such as the solar radiation saltation or linear variation to represent the typical weather variations. The results show that the hybrid system could rapidly reach the steady state in less than about 53 s after the solar radiation saltation increases or decreases by 10%. The response time reflects that the thermal hysteresis of the hybrid system is mainly determined by varying the outlet temperature of R134a from the solar thermal receiver. Meanwhile, when the solar radiation changes linearly, a lower gradient is beneficial to remit the thermal hysteresis of the hybrid system and improve the thermal stability, and the parameters could be treated as the steady state values with a gradient of less than 0.2 W m−2 s−1. Afterward, the quasi-steady state model was used to analyze the all-day dynamic performance of the hybrid system. It shows that the power output and the flow rate are directly related to the direct normal irradiance (DNI), while the outlet temperature of R134a vapor could be almost constant except for the starting and stopping periods.

Experiments on transient performance of a low specific speed centrifugal pump with open impeller

In order to meet the needs in engineering, an existing low specific speed centrifugal pump may have to be run at a high rotating speed. Unfortunately, experiments on transient performance of such a kind of centrifugal pump in starting and stopping periods at a high speed have been unavoidable so far. In this paper, the transient hydraulic performance of a low specific speed centrifugal pump with an open impeller during starting and stopping periods is measured with an updated test rig. The correlations of rotating speed, flow rate, head, static pressures at the pump inlet and outlet, and shaft power with time are obtained at different discharge valve openings. The results show that the flow rate rises slowly at the beginning of starting period, and suddenly drops at the end of stopping process. There is an obvious impact phenomenon in local static pressure curves at the pump inlet and outlet during starting period. With the augment of discharge valve opening, the required time for flow rate to reach a steady value is gradually prolonged, and the impact phenomenon in local static pressures at the pump inlet is postponed and the impact difference is also decreased step by step. The impact phenomenon in shaft powers is also very prominent, especially at small discharge valve openings. At the beginning of stopping process, the flow rate declining delay phenomenon becomes weak with increasing discharge valve opening, and the time for flow to stop fully is also extended gradually.

Multidisciplinary comprehensive hypertension project (MCHP): a two-year progress report from an academic medical center

In this paper, the authors develop a dynamic model of a commercial micro-combined heat and power (mCHP) unit and analyse its dynamic behaviour when the engine is running at different mass flow inputs. The simulation predicts with a low root mean bias error (RMSE) the most important outputs from the cogeneration unit during the starting, steady-state and stopping periods. Furthermore, the presented transient model reproduces the behaviour of the cogeneration unit when the fuel and air mass flows are changing. The obtained results are discussed, and the different possibilities for the variation of the thermal to power ratio are analysed. These combinations include the variation of the flow distribution inside the machine and the position of the exhaust heat exchanger. The power to thermal ratio can be modified between 0.15 and 0.26 for these combinations. The performance of the engine and the variation of the heat source temperature are also analysed theoretically. The simulation results conclude that an important saving could be obtained when the electrical to thermal ratio (ETTR) is tracked for the power or thermal demands from a dwelling.

Adjusting migration schedules at stopping sites: time strategy of a long-distance migratory shorebird during northward migration

Selection of timing to match optimal environments is crucial for migrants that breed at high latitudes where there is a narrow time window suitable for breeding. However, birds generally depart from non-breeding grounds in a broad time window. How birds adjust their migration schedule to match optimal timing of arrival at breeding grounds is largely unexplored. We radio-tracked Great Knots Calidris tenuirostris at stopping sites in the southern and northern Yellow Sea during the entire stopping periods to determine their time schedules during northward migration. Great Knots stayed for 40.7 ± 9.2 days (n = 11) in the whole Yellow Sea, with the early arrivals having a longer length of stay than the late arrivals. There was no significant difference in the length of stay between birds that arrived on various dates in the southern Yellow Sea, while the late arrivals spent less time during flights from the southern to the northern Yellow Sea, and stayed for a shorter time than the early arrivals in the northern Yellow Sea. We estimated that the later arrivals can still moult into full breeding plumage and deposit enough fuel for a flight to the breeding grounds before departure. We propose that early and latter migration are the two ends of migratory schedule, with the former adapting to unpredictable and rigorous environments and the latter to stable and favourable environments en route. Stopping sites play an important role for birds to adjust their migration schedule to meet optimal timing of arrival at migratory destination.

Development of an improved dynamic model of a Stirling engine and a performance analysis of a cogeneration plant

In this paper, the authors develop a dynamic model of a commercial micro-combined heat and power (mCHP) unit and analyse its dynamic behaviour when the engine is running at different mass flow inputs. The simulation predicts with a low root mean bias error (RMSE) the most important outputs from the cogeneration unit during the starting, steady-state and stopping periods. Furthermore, the presented transient model reproduces the behaviour of the cogeneration unit when the fuel and air mass flows are changing. The obtained results are discussed, and the different possibilities for the variation of the thermal to power ratio are analysed. These combinations include the variation of the flow distribution inside the machine and the position of the exhaust heat exchanger. The power to thermal ratio can be modified between 0.15 and 0.26 for these combinations. The performance of the engine and the variation of the heat source temperature are also analysed theoretically. The simulation results conclude that an important saving could be obtained when the electrical to thermal ratio (ETTR) is tracked for the power or thermal demands from a dwelling.

Transient Characteristics of a Closed-Loop Pipe System During Pump Stopping Periods

In order to study the transient characteristics of a closed-loop pipe system with room temperature water, experiments were carried out based on different pump stopping periods from rate rotational speed to zero. Various stopping periods were realized by changing the rotational inertia of the rotors, controlling the frequency of the motor and braking the shaft. Experimental results of different operating schemes were compared, and transient flow rate of the pipe system and transient characteristics of the pump were analyzed. The influences of the kinetic energy of the loop fluid and pump rotors to the stopping periods were summarized. Results show that rapid change of the pump operating conditions occurs during the stopping period and transient flow rate of the pipe system and characteristics of the pump depend largely on the way of stopping. The kinetic energy stored in the pump can drive the impeller keeping rotating for more time after the motor is shutdown. Due to the kinetic energy stored in the loop pipe, the flow rate does not reach zero immediately after the rotational speed reaches zero. The inertia of pump rotor and fluid inertia affect the impact of fluid flow and the duration of the loop during pump stopping period.

Controlled nanostructuration of polycrystalline tungsten thin films

Nanostructured tungsten thin films have been obtained by ion beam sputtering technique stopping periodically the growing. The total thickness was maintained constant while nanostructure control was obtained using different stopping periods in order to induce film stratification. The effect of tungsten sublayers' thicknesses on film composition, residual stresses, and crystalline texture evolution has been established. Our study reveals that tungsten crystallizes in both stable α- and metastable β-phases and that volume proportions evolve with deposited sublayers' thicknesses. α-W phase shows original fiber texture development with two major preferential crystallographic orientations, namely, α-W⟨110⟩ and unexpectedly α-W⟨111⟩ texture components. The partial pressure of oxygen and presence of carbon have been identified as critical parameters for the growth of metastable β-W phase. Moreover, the texture development of α-W phase with two texture components is shown to be the result of a competition between crystallographic planes energy minimization and crystallographic orientation channeling effect maximization. Controlled grain size can be achieved for the α-W phase structure over 3 nm stratification step. Below, the β-W phase structure becomes predominant.

A survey of women's preferences regarding alternative surgical treatments for menorrhagia.

BACKGROUND: Menorrhagia represents a major health burden to a large number of women in the UK. A range of medical and surgical treatments is now available for the condition, but each has its own advantages and limitations. METHODS: A postal survey was undertaken of women with apparently uncomplicated menorrhagia referred to one of two NHS hospitals. The aim was to elicit women's preferences for the characteristics of surgical treatment and, specifically, to assess how they traded-off the characteristics of hysterectomy and minimal access surgery. RESULTS: A total of 221 women returned their questionnaire and were included in the study (59% of those sent out). The characteristics most frequently rated as 'very important' were getting back to usual activities as soon as possible (57%), experiencing the least pain and discomfort (46%), spending a short time in hospital (46%) and stopping periods for good (43%). The single characteristic most frequently rated as the most important by women was stopping periods for good (28%). Similar proportions of women preferred abdominal hysterectomy (43%) and endometrial resection (41%) when these were described to them. When asked to think about specific treatments of which they were aware, strong positive (43%) and negative (42%) preferences were indicated. Women's main information source was their general practitioner (70%), but only 44% considered themselves well-informed about menorrhagia and its treatment. CONCLUSIONS: Many women referred to hospital with menorrhagia have conflicting objectives for treatment, feel under-informed about therapies and have not formed treatment preferences. It is important to develop well-structured and accessible sources of information for women and methods to elicit their treatment preferences, and to evaluate the impact of such tools on treatment selection and outcomes.

Centrifugal pump transient characteristics and analysis using the method of characteristics

A theoretical and experimental study has been carried out on the transient characteristics of a centrifugal pump during starting and stopping periods. Experiments have been conducted on a volute pump with different valve openings to study the dynamic behaviour of the pump during normal start up and stopping, when a small length of discharge pipe line is connected to discharge flange of the pump. Similar experiments have also been conducted when the test pump was part of a hydraulic system to study the system effect on the transient characteristics. Instantaneous rotational speed, flowrate, and delivery and suction pressures of the pump are recorded and it is observed in all the tested cases that the change of pump behaviour during the transient period is quasi-steady. The dynamic characteristics of the pump have been analysed by a numerical model using the method of characteristics. The model is presented and the results are compared with the experimental data. As the model contains speed acceleration and unsteady discharge terms, the model can be applied for analyses of purely unsteady cases where the pump dynamic characteristics show considerable departure from their steady-state characteristics.

A Quasi-Steady Performance Prediction Model for Dynamic Characteristics of a Volute Pump

A performance prediction model generally applicable for volute-type centrifugal pumps has been extended to predict the dynamic characteristics of a pump during its normal starting and stopping periods. Experiments have been conducted on a volute pump with different valve openings to study the dynamic behaviour of the pump during normal start-up and stopping, when a small length of discharge pipeline is connected to the discharge flange of the pump. Such experiments have also been conducted when the test pump was part of a hydraulic system, an experimental rig, where it is pumping against three similar pumps, known as supply pumps, connected in series, with the supply pumps kept idle or running. Instantaneous rotational speed, flowrate, and delivery and suction pressures of the pump were recorded and it was observed in all the tested cases that the change of pump behaviour during the transient period was quasi-steady, which validates the quasi-steady approach presented in this paper. The nature of variation of parameters during the transients has been discussed. The model-predicted dynamic head-capacity curves agree well with the experimental data for almost all the tested cases.

Forced Vibration of a Base-Excited Single-Degree-of-Freedom System With Coulomb Friction

Using the “stopping region of motion” concept, a brief analytical technique is worked out for the behavior of the linear forced vibratory system under the influence of a Coulomb friction force. The following points are clarified by the above technique: 1. The behavior of the system is completely determined by the three non-dimensional parameters of nondimensional friction force, frequency ratio and damping ratio. 2. The vibratory system undergoes a periodic vibration with stopping periods when the mass cannot move. These stopping periods increase at lower exciting frequencies, owing to Coulomb friction. 3. The relation between the kind of motion occurring in the system and the above three parameters can be obtained theoretically and verified experimentally.

アルミニウム板材の水平連続鋳造について

Casting factors in horizontal intermittent continuous casting of commercial pure aluminum such as drawing speed and draw-and-stop cycle were examined. A prolonged cycle of draw-and-stop is required with increases in pitch-length and drawing speed. The casting rate is accelerated with an increase in pitch-length up to 40mm and keeps constant at pitch-length above 40mm. Solidification proceeds both in stopping and drawing periods. Coarse columnar grains in the strip cast at 10mm of a pitch incline toward the reverse direction of casting. The strip cast at 80mm of a pitch has coarse columnar grains which incline toward the reverse direction of casting and needle-like columnar grains periodically.