108 research outputs found
A Sliced Inverse Regression (SIR) Decoding the Forelimb Movement from Neuronal Spikes in the Rat Motor Cortex
Several neural decoding algorithms have successfully converted brain signals into commands to control a computer cursor and prosthetic devices. A majority of decoding methods, such as population vector algorithms (PVA), optimal linear estimators (OLE), and neural networks (NN), are effective in predicting movement kinematics, including movement direction, speed and trajectory but usually require a large number of neurons to achieve desirable performance. This study proposed a novel decoding algorithm even with signals obtained from a smaller numbers of neurons. We adopted sliced inverse regression (SIR) to predict forelimb movement from single-unit activities recorded in the rat primary motor (M1) cortex in a water-reward lever-pressing task. SIR performed weighted principal component analysis (PCA) to achieve effective dimension reduction for nonlinear regression. To demonstrate the decoding performance, SIR was compared to PVA, OLE, and NN. Furthermore, PCA and sequential feature selection (SFS) which are popular feature selection techniques were implemented for comparison of feature selection effectiveness. Among SIR, PVA, OLE, PCA, SFS, and NN decoding methods, the trajectories predicted by SIR (with a root mean square error, RMSE, of 8.47 ± 1.32 mm) was closer to the actual trajectories compared with those predicted by PVA (30.41 ± 11.73 mm), OLE (20.17 ± 6.43 mm), PCA (19.13 ± 0.75 mm), SFS (22.75 ± 2.01 mm), and NN (16.75 ± 2.02 mm). The superiority of SIR was most obvious when the sample size of neurons was small. We concluded that SIR sorted the input data to obtain the effective transform matrices for movement prediction, making it a robust decoding method for conditions with sparse neuronal information
The TOP-SCOPE Survey of Planck Galactic Cold Clumps : Survey Overview and Results of an Exemplar Source, PGCC G26.53+0.17
The low dust temperatures (<14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. "TOP-SCOPE" is a joint survey program targeting similar to 2000 PGCCs in J = 1-0 transitions of CO isotopologues and similar to 1000 PGCCs in 850 mu m continuum emission. The objective of the "TOP-SCOPE" survey and the joint surveys (SMT 10 m, KVN 21 m, and NRO 45 m) is to statistically study the initial conditions occurring during star formation and the evolution of molecular clouds, across a wide range of environments. The observations, data analysis, and example science cases for these surveys are introduced with an exemplar source, PGCC G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total mass, length, and mean line mass (M/L) of the G26 filament are similar to 6200 M-circle dot, similar to 12 pc, and similar to 500 M-circle dot pc(-1), respectively. Ten massive clumps, including eight starless ones, are found along the filament. The most massive clump as a whole may still be in global collapse, while its denser part seems to be undergoing expansion owing to outflow feedback. The fragmentation in the G26 filament from cloud scale to clump scale is in agreement with gravitational fragmentation of an isothermal, nonmagnetized, and turbulent supported cylinder. A bimodal behavior in dust emissivity spectral index (beta) distribution is found in G26, suggesting grain growth along the filament. The G26 filament may be formed owing to large-scale compression flows evidenced by the temperature and velocity gradients across its natal cloud.Peer reviewe
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
Observation of gravitational waves from the coalescence of a 2.5−4.5 M⊙ compact object and a neutron star
Ultralight vector dark matter search using data from the KAGRA O3GK run
Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM
Echocardiographic Parameters and the risk of Cardiovascular Events and All-Cause Death - A Longitudinal Cohort Study in An Ethnic Chinese Community
背景與目標
由於心血管疾病具有高發生率與高盛行率,又是重大死因,因此如何進行心血管疾病的防治,多年來是已開發國家公共衛生上的重要課題。心臟超音波檢查,具有非侵入性、無痛無害、可反覆檢查等許多優勢,是臨床應用及流行病學研究的重要工具。本研究之主要目標在於:從心臟超音波檢查所獲得的資料中,尋找適合於罹病預測、危險分級的重要指標,以方便未來利用超音波指標,篩選出高危險族群,進行重點防治。
方法
本研究利用台灣金山社區心血管疾病世代研究(Chin-Shan Community Cardiovascular Cohort Study, CCCC Study)的資料,以世代研究(cohort study)的研究設計,分析左心室質量、左心房直徑與主動脈根部直徑,3個心臟超音波指標,與腦中風、心血管事件和總死亡事件之間的關係。針對其中具有獨立的預後預測價值的指標,界定出適用於華人族群的危險閾值。並分析在不同的次群體(如性別、年齡)間,個別指標與臨床事件之間的關係是否有所不同。
結果
在左心室質量的研究中,一共有2604名個案被納入,追蹤時間的中位數達到14.4年。在追蹤了34325人年之後,發生心血管事件的個案數為205位,453名個案死亡。左心室質量一律先以體表面積進行校正後,得到左心室質量指數(left ventricular mass index, LVMI),再將個案依LVMI平分成五等分進行分析。經由多變項回歸調整後,LVMI分層與心血管事件的發生有顯著相關:LVMI最高五等分的個案,相較於LVMI最低五等分的個案,發生心血管事件的相對危險是2.01(95% confidence interval [CI], 1.11 to 3.63)倍(p for trend = 0.001)。此外,LVMI與總死亡事件的相關性,違背了線性關係的假設(p = 0.003 for test of linearity),呈現J型曲線模式。LVMI第二個五等分的個案與LVMI第三個五等分的個案,相較於LVMI最低五等分的個案,擁有比較低的總死亡事件相對危險,其相對危險分別是0.58(95% CI, 0.40 to 0.84)倍及0.68(95% CI, 0.47 to 0.96)倍。男性與女性罹患心血管事件的共同危險閾值之LVMI為105 g/m2。
在左心房直徑的研究中,一共收納了1937名個案,追蹤了21733人年(追蹤時間中位數:11.9年)。發生腦中風的個案數為114位,此外,364名個案死亡。由統計檢定,發現身體質量指數最適於用來對左心房直徑進行體型校正,因此以身體質量指數校正後的左心房直徑指數(left atrial dimension index, LADI)進行分析。 所有個案依LADI平分成三等分。以女性而言,經由多變項回歸調整後,LADI高等分的個案,相較於LADI低等分的個案,發生腦中風的相對危險是2.44(95% CI, 1.11 to 5.36)倍(p for trend = 0.029)。不過,此相關性在加入了LVMI做為調整變項後,有明顯減弱的現象(相對危險:2.11倍, 95% CI, 0.88 to 5.02, p for trend = 0.09)。女性發生腦中風的LADI危險閾值為1.39 mm/(kg/m2)。以男性而言,LADI的分層與腦中風的發生無關。此外,不論男女,LADI的分層與總死亡事件的發生無關。
在主動脈根部直徑的研究中,共收納1851名個案,經過11.9年的追蹤,累積達20800人年,共185名個案發生心血管事件,335名個案死亡。主動脈根部直徑以體表面積進行校正後,得到主動脈根部直徑指數(aortic root dimension index, ARDI),再將個案依ARDI平分成三等分進行分析。雖然在單變項回歸模型中,ARDI與心血管事件及總死亡事件皆有相關,但是,一旦調整了性別與年齡因素後,所有的相關都變成不顯著 (心血管事件:p for trend = 0.12;總死亡事件:p for trend = 0.23)。在次群體分析則發現:在年齡=65歲的個案中,ARDI分層與總死亡事件無關(p for trend = 0.14)。不論年齡層高低,ARDI的分層與心血管事件的發生無關。
結論
本研究以台灣金山地區成年華人族群為研究對象,發現:左心室質量指數與心血管事件的發生,呈線性相關;而與總死亡事件的發生,呈現J型曲線相關。左心房直徑指數與女性個案罹患腦中風的危險性呈正相關。另外,針對年齡<65歲的個案,主動脈根部直徑指數與總死亡事件呈顯著的正相關。此三個心臟超音波指標,與臨床事件具有顯著的相關性,可以做為進一步發展臨床事件預測模型的基礎。Background and Objectives:
Because of the great burden of cardiovascular deaths, prevention and treatment of cardiovascular diseases are important in developed countries. Echocardiography possesses the advantage of non-invasiveness and rapid acquisition of parameters about cardiac function. Several population studies have investigated the predictive value of echocardiographic measures for cardiovascular morbidity and mortality. However, some issues including the methods of indexation of echocardiographic parameters are not clarified in the literature. This research was proposed to investigate the relationship between different echocardiographic parameters and clinical outcomes in an ethnic Chinese population.
Methods:
We recruited participants in the Chin-Shan Community Cardiovascular Cohort (CCCC) study who had received echocardiography without previous cardiovascular events as the study population. Three echocardiographic parameters, including left ventricular mass, left atrial dimension and aortic root dimension, were measured through two different sessions of echocardiographic examinations on 1992~1993 and 1994~1995. The end-points were all-cause death and incident cardiovascular events including coronary heart disease and stroke. We proposed to define the best cut-off values for good clinical predictors for risk stratification in our ethnic Chinese population and to test the different prediction power of individual predictor among different subgroups.
Results:
We evaluated 2604 participants in the sub-study concerning left ventricular mass. By the end of 2005, with a median follow-up of 14.4 years, 34325 person-years were accrued. We identified 205 participants with cardiovascular events and 453 deaths. We used body surface area as the indexation to calculate left ventricular mass index (LVMI). The results of multivariate Cox regression analysis showed a linear relationship between LVMI and cardiovascular events. The adjusted relative risk was 2.01 (95% confidence interval [CI], 1.11 to 3.63) for the highest quintile of LVMI compared with the lowest quintile (p for trend = 0.001). A J-shape relationship between LVMI and all-cause death was observed, with the test for a linear relationship being rejected (p = 0.003). The adjusted relative risks of all-cause death were significantly lower for the second quintile of LVMI (0.58, 95% CI, 0.40 to 0.84) and for the third quintile of LVMI (0.68, 95% CI, 0.47 to 0.96), compared with the lowest quintile. The proposed cut-off value of LVMI was 105 g/m2 for prediction of cardiovascular events in both genders.
Concerning the sub-study of left atrial dimension, 1937 subjects were included and 21733 person-years were accrued during a median follow-up of 11.9 years. We identified 114 subjects with stroke and 364 with all-cause death. We found that the best method of indexation was to divide left atrial dimension by body mass index to obtain left atrial dimension index (LADI). In women, the relative risk of stroke was 2.44 (95% CI, 1.11 to 5.36, p for trend = 0.029) among participants in the upper tertile of LADI compared with participants in the lower tertile of LADI after multivariate adjustment. However, further adjustment for left ventricular mass index attenuated the relation of LADI to stroke (relative risk: 2.11, 95% CI, 0.88 to 5.02, p for trend = 0.09). The proposed cut-off value of LADI was 1.39 mm/(kg/m2) for prediction of stroke in women. In men, tertiles of LADI was not associated with stroke. Besides, LADI was not associated with the risk of all-cause death in both genders.
In the sub-study of aortic root dimension, we enrolled 1851 subjects with a median follow-up of 11.9 years. In 20800 person-years of follow-up, 185 subjects were diagnosed as having cardiovascular events and 335 subjects died during the follow-up period. We indexed aortic root dimension by body surface area to obtain aortic root dimension index (ARDI). Although tertiles of ARDI was associated with increased risk of cardiovascular events and all-cause death in univariate analysis, the significance diminished after adjusting for both gender and age (p for trend = 0.12 for cardiovascular events; p for trend = 0.23 for all-cause death). In subgroup analysis, we found a significant association between tertiles of ARDI and risk of all-cause death in the final multivariate Cox regression model in adults = 65 years, tertile of ARDI was not associated with all-cause death (p for trend = 0.14). Tertiles of ARDI was not associated with cardiovascular events throughout this study.
Conclusions:
In this ethnic Chinese cohort study, we demonstrated a linear relationship between LVMI and cardiovascular events, and a J-shape relationship between LVMI and all-cause death. An association between increased LADI and incident stroke in women rather than in men was established. Besides, we found a significant association between ARDI and all-cause death in adults aged < 65 years. Since LVMI, LADI, and ARDI were significantly related with clinical outcomes, they can be enrolled into the models for prediction of clinical events in the future studies
Risk of hip/femur fractures during the initiation period of -adrenoceptor blocker therapy among elderly males: a self-controlled case series study
AimsThis study aimed to evaluate the risk of hip/femur fractures during the initiation period of -adrenoceptor blocker therapy using the National Health Insurance claims database, Taiwan, with a self-controlled case series design. ;MethodsAll male beneficiaries aged over 50years as of 2007, who were incident users of -adrenoceptor blockers and also had a diagnosis of hip/femur fracture within the 2007-2009 study period were identified. The first day when the -adrenoceptor blocker was prescribed was set as the index date. We partitioned the initial 21 day period following the index date as the post-exposure risk period 1, days 22-60 after the index date as the post-exposure risk period 2, the 21 day period prior to the index date as the pre-exposure risk period 1 and days 22-60 prior to the index date as the pre-exposure risk period 2. The remainder of the study period was defined as the unexposed period. The incidence rate ratio (IRR) of hip/femur fractures within each risk period compared with the unexposed period was estimated using a conditional Poisson regression model. ;ResultsA total of 5875 men were included. Compared with the unexposed period, the IRR of hip/femur fractures was 1.36 (95% confidence interval 1.06, 1.74, P = 0.017) within the post-exposure risk period 1 for patients without concomitant prescriptions of anti-hypertensive agents. ;ConclusionsUse of -adrenoceptor blockers was associated with a small but significant increase in the risk of hip/femur fractures during the early initiation period in patients without concomitant prescriptions of anti-hypertensive agents
A Fault Diagnosis Mechanism with Power Generation Improvement for a Photovoltaic Module Array
This paper aims to develop an online diagnostic mechanism, doubling as a maximum power point tracking scheme, for a photovoltaic (PV) module array. In case of malfunction or shadow event occurring to a PV module, the presented diagnostic mechanism is enabled, automatically and immediately, to reconfigure a PV module array for maximum output power operation under arbitrary working conditions. Meanwhile, the malfunctioning or shaded PV module can be located instantly by this diagnostic mechanism according to the array configuration, and a PV module replacement process is made more efficient than ever before for the maintenance crew. In this manner, the intended maximum output power operation can be resumed as soon as possible in consideration of a minimum business loss. Using a particle swarm optimization (PSO)-based algorithm, the PV module array is reconfigured by means of switch manipulations between modules, such that a load is supplied with the maximum amount of output power. For compactness, the PSO-based online diagnostic algorithm is implemented herein using a TMS320F2808 digital signal processor (DSP) and is experimentally validated as successful to identify a malfunctioning PV module at the end of this work
LETTER TO THE EDITOR: "Echocardiographic Left Ventricular Mass in a Multiethnic Southeast Asian Population: Proposed New Gender and Age- Specific Norms"
A letter to the editor is presented in response to the article " Echocardiographic Left Ventricular Mass in a Multiethnic Southeast Asian Population: Proposed New Gender and Age-Specific Norms," by Raymond C. Wong, James Wei-Luen Yip, Anuj Gupta, Hong Yang, and Lieng H. Ling
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