Modified reverse tapering method to prevent frequency shift of the radiation in the planar undulator

This paper presents a modified reverse tapering method to generate a polarized soft x ray in x-ray free-electron lasers (XFELs) with a higher photon power and a shorter undulator length than the simple linear reverse tapering method. In the proposed method, a few untapered planar undulators are added before the simple linear reverse tapering section of the undulator line. This simple modification prevents the frequency shift of the radiation that occurs when the simple linear reverse tapering method is applied to planar undulators. In the proposed method, the total length of planar undulators decreased in spite of the additional untapered undulators. When the modified reverse tapering method is used with four untapered planar undulators, the total length of the planar undulators is 64.6 m. On the other hand, the required length of the planar undulators is 94.6 m when the simple linear reverse tapering method is used. The proposed method gives us a way to generate a soft x-ray pulse (1.24 keV) with a high degree of polarization (>0.99) and radiation power (>30 GW) at the new undulator line with a 10-GeV electron beam in the Pohang Accelerator Laboratory X-ray Free-Electron Laser. This method can be applied in the existing XFELs in the world without any change in the undulator lines. ? 2017 authors. Published by the American Physical Society.111Ysciescopu

The ReInforcement of adherence via self-monitoring app orchestrating biosignals and medication of RivaroXaban in patients with atrial fibrillation and co-morbidities: a study protocol for a randomized controlled trial (RIVOX-AF)

BackgroundBecause of the short half-life of non-vitamin K antagonist oral anticoagulants (NOACs), consistent drug adherence is crucial to maintain the effect of anticoagulants for stroke prevention in atrial fibrillation (AF). Considering the low adherence to NOACs in practice, we developed a mobile health platform that provides an alert for drug intake, visual confirmation of drug administration, and a list of medication intake history. This study aims to evaluate whether this smartphone app-based intervention will increase drug adherence compared with usual care in patients with AF requiring NOACs in a large population.MethodsThis prospective, randomized, open-label, multicenter trial (RIVOX-AF study) will include a total of 1,042 patients (521 patients in the intervention group and 521 patients in the control group) from 13 tertiary hospitals in South Korea. Patients with AF aged ≥19 years with one or more comorbidities, including heart failure, myocardial infarction, stable angina, hypertension, or diabetes mellitus, will be included in this study. Participants will be randomly assigned to either the intervention group (MEDI-app) or the conventional treatment group in a 1:1 ratio using a web-based randomization service. The intervention group will use a smartphone app that includes an alarm for drug intake, visual confirmation of drug administration through a camera check, and presentation of a list of medication intake history. The primary endpoint is adherence to rivaroxaban by pill count measurements at 12 and 24 weeks. The key secondary endpoints are clinical composite endpoints, including systemic embolic events, stroke, major bleeding requiring transfusion or hospitalization, or death during the 24 weeks of follow-up.DiscussionThis randomized controlled trial will investigate the feasibility and efficacy of smartphone apps and mobile health platforms in improving adherence to NOACs.Trial registrationThe study design has been registered in ClinicalTrial.gov (NCT05557123)

An expert consensus for the management of chronic hepatitis B in Asian Americans.

BACKGROUND: Hepatitis B virus (HBV) infection is common with major clinical consequences. In Asian Americans, the HBsAg carrier rate ranges from 2% to 16% which approximates the rates from their countries of origin. Similarly, HBV is the most important cause of cirrhosis, hepatocellular carcinoma (HCC) and liver related deaths in HBsAg positive Asians worldwide. AIM: To generate recommendations for the management of Asian Americans infected with HBV. METHODS: These guidelines are based on relevant data derived from medical reports on HBV from Asian countries as well as from studies in the HBsAg positive Asian Americans. The guidelines herein differ from other recommendations in the treatment of both HBeAg positive and negative chronic hepatitis B (CHB), in the approach to HCC surveillance, and in the management of HBV in pregnant women. RESULTS: Asian American patients, HBeAg positive or negative, with HBV DNA levels \u3e2000 IU/mL (\u3e10 CONCLUSIONS: Application of the recommendations made based on a review of the relevant literature and the opinion of a panel of Asian American physicians with expertise in HBV treatment will inform physicians and improve patient outcomes

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Modified reverse tapering method to prevent frequency shift of the radiation in the planar undulator

This paper presents a modified reverse tapering method to generate a polarized soft x ray in x-ray free-electron lasers (XFELs) with a higher photon power and a shorter undulator length than the simple linear reverse tapering method. In the proposed method, a few untapered planar undulators are added before the simple linear reverse tapering section of the undulator line. This simple modification prevents the frequency shift of the radiation that occurs when the simple linear reverse tapering method is applied to planar undulators. In the proposed method, the total length of planar undulators decreased in spite of the additional untapered undulators. When the modified reverse tapering method is used with four untapered planar undulators, the total length of the planar undulators is 64.6 m. On the other hand, the required length of the planar undulators is 94.6 m when the simple linear reverse tapering method is used. The proposed method gives us a way to generate a soft x-ray pulse (1.24 keV) with a high degree of polarization (>0.99) and radiation power (>30  GW) at the new undulator line with a 10-GeV electron beam in the Pohang Accelerator Laboratory X-ray Free-Electron Laser. This method can be applied in the existing XFELs in the world without any change in the undulator lines

Toward the Generation of an Isolated TW-Attosecond X-ray Pulse in XFEL

The isolated terawatt (TW) attosecond (as) hard X-ray pulse will expand the scope of ultrafast science, including the examination of phenomena that have not been studied before, such as the dynamics of electron clouds in atoms, single-molecule imaging, and examining the dynamics of hollow atoms. Therefore, several schemes for the generation of an isolated TW-as X-ray pulse in X-ray free electron laser (XFEL) facilities have been proposed with the manipulation of electron properties such as emittance or current. In a multi-spike scheme, a series of current spikes were employed to amplify the X-ray pulse. A single-spike scheme in which a TW-as X-ray pulse can be generated by a single current spike was investigated for ideal parameters for the XFEL machine. This paper reviews the proposed schemes and assesses the feasibility of each scheme

Isolated terawatt sub-attosecond high-energy x-ray pulse generated by an x-ray free-electron laser

The endless quest for dynamics in natural phenomena has resulted in the generation and application of attosecond pulses to trace electron dynamics in atomic and molecular systems. The next challenge is to generate powerful pulses on the zeptosecond time scale, which is currently inaccessible. Through a simulation study, a new type of x-ray source that can generate an isolated terawatt sub-attosecond pulse at high-energy x rays by combining attosecond pulse technology with free-electron laser technology is proposed. The successful generation of a sub-attosecond pulse necessitates the consideration of nanometer-wide current-spikes, the sub-attosecond pulse amplification, and pulse duration and background noise control. The underlying interaction mechanism between a sub-attosecond pulse and a current-spike is closely investigated using the simulation results. The proposed method is expected to produce an isolated ~700 zs pulse with a peak output of 2.9 TW at a photon energy of 247.5 keV. (C) 2022 Author(s).11Ysciescopu

머신러닝을 이용한 전자빔의 longitudinal Phase Space 예측

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