Coupling of pinned magnetic moments in an antiferromagnet to a ferromagnet and its role for exchange bias

The interaction between uncompensated pinned magnetic moments within an antiferromagnetic (AFM) layer and an adjacent ferromagnetic (FM) layer responsible for the existence of exchange bias is explored in epitaxially grown trilayers of the form FM2/AFM/FM1 on Cu3Au(0 0 1) where FM1 is ~12 atomic monolayers (ML) Ni, FM2 is 21–25 ML Ni, and AFM is 27 ML or 50 ML Ni~25Mn~75. Field cooling for parallel or antiparallel alignment of the out-of-plane magnetizations of the two FM layers does not make a difference for the temperature-dependent coercivity (H C), magnitude of exchange bias field (H eb), AFM ordering temperature (T AFM), and blocking temperature for exchange bias (T b). We explain this by a model in which the uncompensated pinned magnetic moments distributed within the volume of the AFM layer interact with both of the FM layers, albeit with different strength. Parallel and antiparallel coupling between the magnetization of the pinned moments and the FM layers equally exists. This leads to the experimentally observed independence of H C, H eb, as well as of T AFM and T b on the magnetization direction of the FM layers during field cooling. These results provide new and detailed insight into revealing the subtle and complex nature of the exchange bias effect

Analyzing Delay in Wireless Multi-hop Heterogeneous Body Area Networks

With increase in ageing population, health care market keeps growing. There is a need for monitoring of health issues. Wireless Body Area Network (WBAN) consists of wireless sensors attached on or inside human body for monitoring vital health related problems e.g, Electro Cardiogram (ECG), Electro Encephalogram (EEG), ElectronyStagmography (ENG) etc. Due to life threatening situations, timely sending of data is essential. For data to reach health care center, there must be a proper way of sending data through reliable connection and with minimum delay. In this paper transmission delay of different paths, through which data is sent from sensor to health care center over heterogeneous multi-hop wireless channel is analyzed. Data of medical related diseases is sent through three different paths. In all three paths, data from sensors first reaches ZigBee, which is the common link in all three paths. Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunication System (UMTS) are connected with ZigBee. Each network (WLAN, WiMAX, UMTS) is setup according to environmental conditions, suitability of device and availability of structure for that device. Data from these networks is sent to IP-Cloud, which is further connected to health care center. Delay of data reaching each device is calculated and represented graphically. Main aim of this paper is to calculate delay of each link in each path over multi-hop wireless channel.Comment: arXiv admin note: substantial text overlap with arXiv:1208.240

Simulation Analysis of Medium Access Techniques

This paper presents comparison of Access Techniques used in Medium Access Control (MAC) protocol for Wireless Body Area Networks (WBANs). Comparison is performed between Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), Pure ALOHA and Slotted ALOHA (S-ALOHA). Performance metrics used for comparison are throughput (T), delay (D) and offered load (G). The main goal for comparison is to show which technique gives highest Throughput and lowest Delay with increase in Load. Energy efficiency is major issue in WBAN that is why there is need to know which technique performs best for energy conservation and also gives minimum delay.Comment: NGWMN with 7th IEEE International Conference on Broadband and Wireless Computing, Com- munication and Applications (BWCCA 2012), Victoria, Canada, 201

Transmission Delay of Multi-hop Heterogeneous Networks for Medical Applications

Nowadays, with increase in ageing population, Health care market keeps growing. There is a need for monitoring of Health issues. Body Area Network consists of wireless sensors attached on or inside human body for monitoring vital Health related problems e.g, Electro Cardiogram (ECG), ElectroEncephalogram (EEG), ElectronyStagmography(ENG) etc. Data is recorded by sensors and is sent towards Health care center. Due to life threatening situations, timely sending of data is essential. For data to reach Health care center, there must be a proper way of sending data through reliable connection and with minimum delay. In this paper transmission delay of different paths, through which data is sent from sensor to Health care center over heterogeneous multi-hop wireless channel is analyzed. Data of medical related diseases is sent through three different paths. In all three paths, data from sensors first reaches ZigBee, which is the common link in all three paths. After ZigBee there are three available networks, through which data is sent. Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunication System (UMTS) are connected with ZigBee. Each network (WLAN, WiMAX, UMTS) is setup according to environmental conditions, suitability of device and availability of structure for that device. Data from these networks is sent to IP-Cloud, which is further connected to Health care center. Main aim of this paper is to calculate delay of each link in each path over multihop wireless channel.Comment: BioSPAN with 7th IEEE International Conference on Broadband and Wireless Computing, Communication and Applications (BWCCA 2012), Victoria, Canada, 201

The XMM-Newton Iron Line Profile of NGC 3783

We report on observations of the iron K line in the nearby Seyfert 1 galaxy, NGC 3783, obtained in a long, 2 orbit (240 ks) XMM-Newton observation. The line profile obtained exhibits two strong narrow peaks at 6.4 keV and at 7.0 keV, with measured line equivalent widths of 120 and 35 eV respectively. The 6.4 keV emission is the K-alpha line from near neutral Fe, whilst the 7.0 keV feature probably originates from a blend of the neutral Fe K-beta line and the H-like line of Fe at 6.97 keV. The relatively narrow velocity width of the K-alpha line (<5000 km/s), its lack of response to the continuum emission on short timescales and the detection of a neutral Compton reflection component are all consistent with a distant origin in Compton-thick matter such as the putative molecular torus. A strong absorption line from highly ionized iron (at 6.67 keV) is detected in the time-averaged iron line profile, whilst the depth of the feature appears to vary with time, being strongest when the continuum flux is higher. The iron absorption line probably arises from the highest ionization component of the known warm absorber in NGC 3783, with an ionization of logxi=3 and column density of 5x10^{22}cm{-2} and may originate from within 0.1pc of the nucleus. A weak red-wing to the iron K line profile is also detected below 6.4 keV. However when the effect of the highly ionized warm absorber on the underlying continuum is taken into account, the requirement for a relativistic iron line component from the inner disk is reduced.Comment: 34 pages, including 11 figures. Accepted for publication in Ap

The nature of a broad line radio galaxy: Simultaneous RXTE and Chandra HETG observations of 3C 382

We present the results from simultaneous chandra and rxte observations of the X-ray bright Broad-Line Radio Galaxy (BLRG) 3C 382. The long (120 ks) exposure with chandra HETG allows a detailed study of the soft X-ray continuum and of the narrow component of the Fe Kalpha line. The rxte PCA data are used to put an upper limit on the broad line component and constrain the hard X-ray continuum. A strong soft excess below 1 keV is observed in the time-averaged HETG spectrum, which can be parameterized with a steep power law or a thermal model. The flux variability at low energies indicates that the origin of the soft excess cannot be entirely ascribed to the circumnuclear diffuse emission, detected by chandra on scales of 20-30 arcsec (22-33 kpc). A narrow (sigma<90 eV) Fe Kalpha line (with EW< 100 eV) is observed by the chandra HEG. Similar values for the line parameters are measured by the rxte PCA, suggesting that the contribution from a broad line component is negligible. The fact that the exposure is split into two observations taken three days apart allows us to investigate the spectral and temporal evolution of the source on different timescales. Significant flux variability associated with spectral changes is observed on timescales of hours and days. The spectral variability is similar to that observed in radio-quiet AGN ruling out a jet-dominated origin of the X-rays.Comment: 19 pages, 10 figures, 3 tables, accepted for publication in Ap

The Cores of the Fe K Lines in Seyfert I Galaxies Observed by the Chandra High Energy Grating

We report on the results of 18 observations of the core, or peak, of the Fe K emission line at $\sim 6.4$ keV in 15 Seyfert I galaxies using the {\it Chandra} High Energy Grating (HEG). These data afford the highest precision measurements of the peak energy of the Fe K line, and the highest spectral resolution measurements of the width of the core of the line to date. We were able to measure the peak energy in 17 data sets, and, excluding a very deep observation of NGC 3783, we obtained a weighted mean of $6.404 \pm 0.005$ keV. In all 15 sources the two-parameter, 99% confidence errors on the line peak energy do not exclude fluorescent $K\alpha$ line emission from Fe {\sc i}, although two sources (Mkn 509 and 3C 120) stand out as very likely being dominated by $K\alpha$ emission from Fe {\sc xvii} or so. We were able to measure the line core width in 14 data sets and obtained a weighted mean of 2380 +/- 760 km/s FWHM (excluding the NGC 3783 deep exposure), a little larger than the instrument resolution. However, there is evidence of underlying broad line emission in at least 4 sources. In fact, the width of the peak varies widely from source to source and it may in general have a contribution from the outer parts of an accretion disk {\it and} more distant matter. For the disk contribution to also peak at 6.4 keV requires greater line emissivity at hundreds of gravitational radii than has been deduced from previous studies of the Fe K line.Comment: Accepted for publication in the Astrophysical Journal. 15 pages, four figures, two of them color. Abstract is slightly abridge

Оценка боли при применении комбинации фентанил-пропофол: два уровня дозировки

Background. In the field of intravenous anesthesia, propofol is widely utilized as an induction agent. However, Propofol injection pain is a frequent adverse event that may result in discomfort for patients. Various strategies have been investigated to prevent or alleviate this pain, considering the presence of opioid receptors in the primary afferent nerve endings of peripheral tissues, which suggests a potential role of opioids in mitigating propofol-induced pain. Fentanyl, a short-acting pure opioid agonist commonly used for systemic analgesia during intraoperative and postoperative periods, has been found to possess peripherally mediated analgesic properties within its clinical dosage range. Therefore, the objective of this study was to evaluate the efficacy of a low dose of fentanyl in the fentanyl-propofol combination for reducing propofol injection pain.The objective of our study was to evaluate and compare the efficacy of two distinct doses of fentanyl in mitigating the pain associated with propofol injection.Materials and methods. The study enrolled 90 patients classified as ASA I–II who were scheduled for elective surgery. The study spanned over 4 months, from November 2022 to April 2023, and included patients aged 19 to 65 years. Patients were divided into three groups, each comprising 30 patients. The control group received only 5 ml (50 mg) of propofol. The group M1 received only 5 ml of a mixture of fentanyl and propofol, prepared with 20 ml (200 mg) of propofol and 2 ml (100 μg) of fentanyl, while the group M2 received only 5 ml of a mixture of fentanyl and propofol, prepared with 20 ml (200 mg) of propofol and 4 ml (200 μg) of fentanyl, at an injection speed of 0.5 ml/s. After 10 seconds of medication, patients were asked a standard question about the comfort of the injection, and a verbal rating scale (VRS) was used to assess propofol injection pain. Anesthesia induction was then continued following standard protocols. Statistical significance was set at p &lt; 0.05 for all analyses.Results. The three groups were found to be similar in terms of patient characteristics. In the control group, the incidence of severe pain upon propofol injection was 46.7%, whereas it was 0% in both groups M1 and M2 (p &lt; 0.05).Conclusion. The combination of fentanyl and propofol has been shown to effectively reduce the incidence of propofol injection pain. Interestingly, in this study, no significant difference was observed between the two different doses of fentanyl used in the mixture. This suggests that a low dose of fentanyl may be sufficient in achieving a pain-free environment during propofol induction, thereby offering a cost-effective approach in clinical practice.Актуальность. Пропофол широко используется в качестве средства для вводной анестезии. Однако частым побочным эффектом является боль при его инъекции, которая может привести к дискомфорту у пациентов. Были исследованы различные стратегии предотвращения или облегчения этой боли, учитывая наличие опиоидных рецепторов в первичных афферентных нервных окончаниях периферических тканей, что позволяет предположить потенциальную роль опиоидов в смягчении боли, вызванной пропофолом. Было обнаружено, что фентанил, чистый опиоидный агонист короткого действия, обычно используемый для системной анальгезии во время интраоперационного и послеоперационного периодов, обладает периферически опосредованными анальгетическими свойствами в пределах его клинической дозировки. Таким образом, задачей данного исследования было оценить эффективность низкой дозы фентанила в комбинации «фентанил–пропофол» для уменьшения боли при инъекции пропофола.Цель – оценить и сравнить эффективность двух различных доз фентанила в облегчении боли, связанной с инъекцией пропофола.Материалы и методы. В исследовании приняли участие 90 пациентов, имеющих риск по шкале ASA I–II, которым была назначена плановая операция. Исследование длилось более 4 месяцев с ноября 2022 г. по апрель 2023 г. и включало пациентов в возрасте от 19 до 65 лет. Пациенты были разделены на 3 группы, каждая из которых состояла из 30 пациентов. Контрольная группа получала только 5 мл (50 мг) пропофола. 1 группа получала только 5 мл смеси фентанила и пропофола, приготовленной из 20 мл (200 мг) пропофола и 2 мл (100 мкг) фентанила, в то время как 2 группа получала только 5 мл смеси фентанила и пропофола, приготовленной из 20 мл (200 мг) пропофола и 4 мл (200 мкг) фентанила со скоростью инъекции 0,5 мл/с. После 10 секунд введения препарата пациентам задавали стандартный вопрос о комфортности инъекции и словесную оценочную шкалу (VRS). Результаты. Было установлено, что статистически значимых различий между пациентами этих групп не было, т. е. группы были однородны. В контрольной группе частота возникновения сильной боли при инъекции пропофола составила 46,7%, тогда как в 1 и 2 группах она составила 0% (р &lt; 0,05).Вывод. Было показано, что комбинация фентанила и пропофола эффективно снижает частоту возникновения боли при инъекции пропофола. Интересно, что в этом исследовании не наблюдалось существенной разницы между 2 различными дозами фентанила, использованными в смеси. Это говорит о том, что низкой дозы фентанила может быть достаточно для купирования боли во время введения пропофола, тем самым предлагая экономически эффективный подход в клинической практике