Are the magnetic fields of millisecond pulsars ~ 10^8 G?

It is generally assumed that the magnetic fields of millisecond pulsars (MSPs) are $\sim 10^{8}$G. We argue that this may not be true and the fields may be appreciably greater. We present six evidences for this: (1) The $\sim 10^{8}$ G field estimate is based on magnetic dipole emission losses which is shown to be questionable; (2) The MSPs in low mass X-ray binaries (LMXBs) are claimed to have $< 10^{11}$ G on the basis of a Rayleygh-Taylor instability accretion argument. We show that the accretion argument is questionable and the upper limit $10^{11}$ G may be much higher; (3) Low magnetic field neutron stars have difficulty being produced in LMXBs; (4) MSPs may still be accreting indicating a much higher magnetic field; (5) The data that predict $\sim 10^{8}$ G for MSPs also predict ages on the order of, and greater than, ten billion years, which is much greater than normal pulsars. If the predicted ages are wrong, most likely the predicted $\sim 10^{8}$ G fields of MSPs are wrong; (6) When magnetic fields are measured directly with cyclotron lines in X-ray binaries, fields $\gg 10^{8}$ G are indicated. Other scenarios should be investigated. One such scenario is the following. Over 85% of MSPs are confirmed members of a binary. It is possible that all MSPs are in large separation binaries having magnetic fields $> 10^{8}$ G with their magnetic dipole emission being balanced by low level accretion from their companions.Comment: 16 pages, accept for publication in Astrophysics and Space Scienc

Investigation of Some Physical Properties of Accretion Induced Collapse in Producing Millisecond Pulsars

We investigate some physical characteristics of Millisecond Pulsar (MSP) such as magnetic fields, spin periods and masses, that are produced by Accretion Induced Collapse (AIC) of an accreting white dwarf (WD) in stellar binary systems. We also investigate the changes of these characteristics during the mass-transfer phase of the system in its way to become a MSP. Our approach allows us to follow the changes in magnetic fields and spin periods during the conversion of WDs to MSPs via AIC process. We focus our attention mainly on the massive binary WDs (M > 1.0Msun) forming cataclysmic variables, that could potentially evolve to reach Chandrasekhar limit, thereafter they collapse and become MSPs. Knowledge about these parameters might be useful for further modeling of the observed features of AIC.Comment: 9 Pages, 4 figure

Mooring line fatigue damage evaluation for floating marine energy converters: Field measurements and prediction

publication-status: Publishedtypes: ArticleThe vision of large-scale commercial arrays of floating marine energy converters (MECs) necessitates the robust, yet cost-effective engineering of devices. Given the continuous environmental loading, fatigue has been iden- tified as one of the key engineering challenges. In particular the mooring sys- tem which warrants the station-keeping of such devices is subject to highly cyclic, non-linear load conditions, mainly induced by the incident waves. To ensure the integrity of the mooring system the lifecycle fatigue spec- trum must be predicted in order to compare the expected fatigue damage against the design limits. The fatigue design of components is commonly as- sessed through numerical modelling of representative load cases. However, for new applications such as floating marine energy converters numerical models are often scantily validated. This paper describes an approach where load measurements from large- scale field trials at the South West Mooring Testing Facility (SWMTF) are used to calculate and predict the fatigue damage. The described procedure employs a Rainflow cycle analysis in conjunction with the Palmgren-Miner rule to estimate the accumulated damage for the deployment periods and individual sea states. This approach allows an accurate fatigue assessment and prediction of mooring lines at a design stage, where field trial load measurements and wave climate information of potential installation sites are available. The mooring design can thus be optimised regarding its fatigue life and costly safety factors can be reduced. The proposed method also assists in monitoring and assessing the fatigue life during deployment periods

Construction status and prospects of the Hyper-Kamiokande project

The Hyper-Kamiokande project is a 258-kton Water Cherenkov together with a 1.3-MW high-intensity neutrino beam from the Japan Proton Accelerator Research Complex (J-PARC). The inner detector with 186-kton fiducial volume is viewed by 20-inch photomultiplier tubes (PMTs) and multi-PMT modules, and thereby provides state-of-the-art of Cherenkov ring reconstruction with thresholds in the range of few MeVs. The project is expected to lead to precision neutrino oscillation studies, especially neutrino CP violation, nucleon decay searches, and low energy neutrino astronomy. In 2020, the project was officially approved and construction of the far detector was started at Kamioka. In 2021, the excavation of the access tunnel and initial mass production of the newly developed 20-inch PMTs was also started. In this paper, we present a basic overview of the project and the latest updates on the construction status of the project, which is expected to commence operation in 2027

Prospects for neutrino astrophysics with Hyper-Kamiokande

Hyper-Kamiokande is a multi-purpose next generation neutrino experiment. The detector is a two-layered cylindrical shape ultra-pure water tank, with its height of 64 m and diameter of 71 m. The inner detector will be surrounded by tens of thousands of twenty-inch photosensors and multi-PMT modules to detect water Cherenkov radiation due to the charged particles and provide our fiducial volume of 188 kt. This detection technique is established by Kamiokande and Super-Kamiokande. As the successor of these experiments, Hyper-K will be located deep underground, 600 m below Mt. Tochibora at Kamioka in Japan to reduce cosmic-ray backgrounds. Besides our physics program with accelerator neutrino, atmospheric neutrino and proton decay, neutrino astrophysics is an important research topic for Hyper-K. With its fruitful physics research programs, Hyper-K will play a critical role in the next neutrino physics frontier. It will also provide important information via astrophysical neutrino measurements, i.e., solar neutrino, supernova burst neutrinos and supernova relic neutrino. Here, we will discuss the physics potential of Hyper-K neutrino astrophysics

Effect of area postrema lesion on low-frequency arterial pressure oscillations in dogs

To explore the possibility that chronic inactivation of the area postrema (AP) may alter the frequency distribution of oscillations in blood pressure, the power spectra for mean arterial pressure (MAP) were evaluated in conscious dogs before and after heat coagulation (n = 4) or sham lesions (n = 6) of the AP. No significant changes in MAP were observed in either group of dogs after surgery. Tachycardia was seen in AP-lesioned animals after surgery; no consistent changes in heart rate were found in sham-lesioned dogs. Spectra were averaged to provide a group spectral estimate for the AP-lesioned and sham-lesioned groups, respectively, for each experimental period. In the sham-lesioned group a variance peak was observed at approximately 0.03 Hz both before and after surgery. The same peak was seen in the AP-lesioned group during the control period but disappeared following AP lesion, apparently because a greater proportion of the variance was shifted toward frequencies below 0.03 Hz. In addition, a peak related to respiratory rate was present in both groups before surgery but was selectively abolished by AP lesion. AP lesion also substantially reduced the power associated with frequencies between 0.1 and 0.4 Hz. The use of spectral analysis has allowed us to demonstrate that a low-frequency oscillation of MAP in conscious, resting dogs requires the integrity of the AP and that the 0.1- to 0.4-Hz components of the variability of MAP are attenuated after removal of the AP.(ABSTRACT TRUNCATED AT 250 WORDS

Effect of area postrema lesion on low-frequency arterial pressure oscillations in dogs

To explore the possibility that chronic inactivation of the area postrema (AP) may alter the frequency distribution of oscillations in blood pressure, the power spectra for mean arterial pressure (MAP) were evaluated in conscious dogs before and after heat coagulation (n = 4) or sham lesions (n = 6) of the AP. No significant changes in MAP were observed in either group of dogs after surgery. Tachycardia was seen in AP-lesioned animals after surgery; no consistent changes in heart rate were found in sham-lesioned dogs. Spectra were averaged to provide a group spectral estimate for the AP-lesioned and sham-lesioned groups, respectively, for each experimental period. In the sham-lesioned group a variance peak was observed at approximately 0.03 Hz both before and after surgery. The same peak was seen in the AP-lesioned group during the control period but disappeared following AP lesion, apparently because a greater proportion of the variance was shifted toward frequencies below 0.03 Hz. In addition, a peak related to respiratory rate was present in both groups before surgery but was selectively abolished by AP lesion. AP lesion also substantially reduced the power associated with frequencies between 0.1 and 0.4 Hz. The use of spectral analysis has allowed us to demonstrate that a low-frequency oscillation of MAP in conscious, resting dogs requires the integrity of the AP and that the 0.1- to 0.4-Hz components of the variability of MAP are attenuated after removal of the AP.(ABSTRACT TRUNCATED AT 250 WORDS

Central depletion of angiotensinogen is associated with elevated AT1 receptors in the SFO and PVN

The brain renin-angiotensin system (RAS) is important in fluid balance and blood pressure regulation. In this study, we compared angiotensin (Ang) receptor density in the subfornical organ (SFO) and paraventricular nucleus (PVN) of a) brain angiotensinogen deficient rats (ASrAogen); b) those with high levels of brain Ang II [(mRen2)27]; c) Hannover Sprague Dawley (SD) rats at 48 and 68 wks of age. Since there was no difference between the two ages in any of the three strains, the data from the 48 and 68 wk time points were combined. There was a significantly higher level of AT1 receptors in the SFO and PVN of ASrAogen animals compared to both the SD and (mRen2)27 rats. This suggests that the brain RAS is important in regulating receptor density and that the differences may be explained by lower levels of the peptide locally. These higher levels of receptors suggest that the ASrAogen animals in adulthood and early aging would be more sensitive to either circulating or endogenous brain Ang II than the SD animals of similar age. In contrast, the similar receptor density in the (mRen2)27 and SD rats suggest that previous reports of reduced responses in the (mRen2)27 rats may result from differences in post receptor mechanisms such as intracellular signaling. Moreover, our data reveal that functional assessments are necessary in addition to receptor density levels to understand the consequences of long-term alterations in brain tissue peptides