Computing the Meridional Overturning Circulation from NEMO Output

With this script, the Meridional Overturning Circulation (MOC) can be computed from NEMO ocean-model output for the whole globe or the Atlantic (AMOC), Indic (IMOC) and Pacific (PMOC) subbasins. The MOC is computable in z- and sigma coordinates. Moreover, for nested configurations, it is possible to combine data from both host and nest grids. Finally, it is possible to take into account of that the ORCA model grid is curvilinear north of 20°N: it is possible to compute the northward velocity component from the velocity field in x- and y- directions and to sum up the meridional flux over latitudional bands instead of in x-direction. When both steps are applied, the resulting MOC shows however strong variability in meridional direction. It needs to be clarified, whether this is realistic or not. The software is provided in the form of the jupyter notebook "MOC.ipynb" which includes more informations on the possibilites of the computations and an extensive appendix section with comparisons to computations with cdftools, as well as with details on the computation of the MOC including nest data and taking the curvilinearity of the grid into account. Necessary python modules are listed at the beginning of the document.

Myocardial stress of the left ventricle during occupational vibration

Aim. Study of intramyocardial stress of the left ventricle (LV) in persons exposed to occupational vibration and patients with hand-arm vibration syndrome (HAVS). Materials and methods. We examined 15 individuals exposed to vibration, 44 individuals with grade 1 HAVS, 10 individuals with grade 2. The control group consisted of 20 persons without cardiovascular pathology, who had not been exposed to hazardous occupational factors. The main occupational hazards in persons with HAVS were vibration, noise, physical exertion. Echocardiography was carried out to determine the total volume of LV (Vtotal); the volume of myocardium (Vm); myocardial mass (LVMM); myocardial mass index (LVMMI); systolic intraventricular pressure; the intensity of the functioning of the LV structures; LV circumferential and meridional diastolic and systolic stresses (σcd, σcs and σmd, σms respectively); LV tension in the circumferential and meridional direction during systole and diastole (Tcs, Tcd and Tms, Tmd respectively). Results. In persons exposed to vibration, in comparison with those who have not been exposed to occupational hazards, there is an increase in σmd by 2.5 times (p < 0.05) and σcd by 2.8 times (p < 0.05). The tension increases during systole and diastole both in the circumferential (Tcs by 17.35%, p < 0.05; Tms by 2.74 times, p < 0.05) and in the meridional (Tcd by 14.59%, p < 0.05; Tmd by 2.76 times, p < 0.05) directions. In persons with grade 1 HAVS, there is an increase during diastole σmd by 2.2 times (p < 0.05), σcd by 2.4 times (p < 0.05), and Tmd (p < 0.05) and Tms by 2.5 times (p < 0.05). In patients with grade 2 HAVS, in contrast to those with grade 1 and persons exposed to vibration, there is a change in the working conditions of LV. With the same values of Vtotal, Vm, LVMM and LVMMI, as in the described groups, in patients with grade 2 HAVS, there is a decrease by 12.3% (p < 0.05) in systolic intraventicular pressure against the background of an increase in σmd by 14.7% (p < 0.05), Tmd by 13.6% (p < 0.05), as well as σms by 2.25 times (p < 0.05) and Tcd by 1.97 times (p < 0.05). Conclusion. In the group of persons exposed to vibration and patients with grade 1 HAVS, in contrast to those who are not exposed to occupational hazards, there is an increase in stress and tension, primarily in the circumferential direction during diastole, which indicates the activation of the heterometric type of autoregulation of activity of the heart. In patients with grade 2 HAVS, stress and tension increase in the meridional direction during systole, which indicates the levelling of LV hyperfunction by isotonic type.

Planography of burial mounds located on the territory of the Loktevsky district (by the results of the survey company in 2021)

The article publishes observations on the planography of burial mounds located on the territory of the Loktevsky district of the Altai Territory. The source base of the study was made up of survey materials of 70 objects of archaeological heritage. The following planographic contexts are noted in the arrangement of the mounds: single mounds, paired mounds, «asystemless» cluster of three or more mounds, mound groups forming chains oriented in the meridional direction. The relationship of the location of most of the surveyed objects with the watershed system has been established. Probably, the location of the burial space was determined by the principle of choosing the highest and furthest from the water territory. This approach could be based on the utilitarian-practical and cult views of the builders.

CHERTOMLYK AND KOZEL: BARROWS, HORSES AND CROSSING

According to Dr. Yu. Boltrik’s works the Scythian royal barrows were situated on the high places (watersheds) as well as along the roads. One of the biggest roads marked by Oguz, Solokha, Kozel, Chertomlyk and Alexandropol barrows run in meridional direction and crossed the Dnieper. The Dnieper crossing was a start point in barrow creation: the later is a barrow, the more distant from the Dnieper crossing it is placed. Kozel and Chertomlyk barrows situated across the Dnieper (Kozel on the left coast, Chertomlyk — on the right one), both dated to the second half of the 4th century BC, are similar in planigraphy, quantity of buried horses and some details of their arrangement. In both barrows the horses were buried in special tombs situated to the West of the central tomb. Each horse tomb consisted of three large rectangular separate pits formed a line situated North-South. In both cases 11 horses were buried. Their bridles were made of two metals: of silver and gold in Chertomlyk and of bronze and silver — in Kozel. Some had also saddles with golden plates and some had bronze breast (neck) dressings. We compared the arrangement of horses in the tombs of Kozel and Chertomlyk concerning the Dnieper crossing and observed a kind of bilateral symmetry in it. So we may suppose they had in mind this crossing not only constructing barrows but burying horses too. River crossing in archaic cultures is a border dangerous to overcome. Because of that some rituals should be performed and some constructions installed at that place. Near the Dnieper crossing a group of Scythian barrows is known. The Dnieper direction in this place is latitudinal and the direction of road — meridional, so the place of crossing looks like a center of sacred space, and the way to it is also sacred. So we do not except the Dnieper crossing was significant for arranging horses’ tombs in Kozel and Chertomlyk barrows.

Bent Bragg–Laue monochromator for high-energy X-rays

A bent Bragg–Laue monochromator (BLM) is proposed for high-energy X-ray (∼25–60 keV) beamlines. The BLM has the unique feature of bi-directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. It is shown that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. Detailed ray tracings indicate that a BLM can provide similar energy resolution and higher flux density compared to a sagittally bent double-Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. In general, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.

Spatial Actuation Effectiveness of Segmented Actuators on Parabolic Cylindrical Panels

With the distinct capability of line-focusing, open parabolic cylindrical panels are commonly used as key components of radar antennas, space reflectors, solar collectors, etc. These structures suffer unexpected vibrations from the fluctuation of base structure, non-uniform heating and air flow. The unwanted vibration will reduce the surface reflecting precision and even result in structure damages. To explore active vibration and shape control of parabolic cylindrical panels, this study focuses on actuation effectiveness induced by segmented piezoelectric patches laminated on a flexible parabolic cylindrical panel. The mathematical model of a parabolic cylindrical panel laminated with distributed actuators is formulated. The segmentation technique is developed and applied to parabolic cylindrical panels, and the piezoelectric layer is segmented uniformly in the meridional direction. The distributed actuator patches induced modal control forces are evaluated. As the area of actuator patch varies in the meridional direction, modal control force divided by actuator area, i.e., actuation effectiveness, is investigated. Spatial actuation effectiveness, including its membrane and bending components are evaluated with respect to design parameters: actuator size and position, shell curvature, shell thickness and vibration mode in case studies. The actuation component induced by the membrane force in the meridional direction mainly contributes to the total actuation effectiveness for lower modes. Average and cancellation effect of various actuator sizes and the optimal actuator position are also discussed. Results suggest that for odd vibration modes, the maximal actuation effectiveness locates at the ridge of the panel; while for even modes, the peak/valley closest to the ridge is the optimal position to obtain the maximal actuation effectiveness. A segmentation scheme of the meridian interval angle 0.0464rad for the investigated standard panel is a preferred tradeoff between the actuation effectiveness and practical feasibility. The modal actuation effectiveness increases with the shell curvature, whereas decreases when the shell thickens.

Statistical characteristics of gravity wave activities observed by an OH airglow imager at Xinglong, in northern China

An all-sky airglow imager (ASAI) was installed at Xinglong, in northern China (40.2° N, 117.4° E) in November 2009 to study the morphology of atmospheric gravity waves (AGWs) in the mesosphere and lower thermosphere (MLT) region. Using one year of OH airglow imager data from December 2009 to November 2010, the characteristics of short-period AGWs are investigated and a yearlong AGW climatology in northern China is first ever reported. AGW occurrence frequency in summer and winter is higher than that in equinoctial months. Observed bands mainly have horizontal wavelengths from 10 to 35 km, observed periods from 4 to 14 min and observed horizontal phase speeds in the range of 30 to 60 m s−1. Most of the bands propagate in the meridional direction. The propagation directions of the bands show a strong southwestward preference in winter, while almost all bands propagate northeastward in summer. Although the wind filtering in the middle atmosphere may control AGW propagations in the zonal direction, the non-uniform distribution of wave sources in the lower atmosphere may contribute to the anisotropy in the meridional direction in different seasons. Additionally, as an indication of local instability, the characteristics of ripples are also analyzed. It also shows seasonal variations, occurring more often in summer and winter and mainly moving westward in summer and eastward in winter.

The accuracy of using the spectral width boundary measured in off-meridional SuperDARN HF radar beams as a proxy for the open-closed field line boundary

Determining reliable proxies for the ionospheric signature of the open-closed field line boundary (OCB) is crucial for making accurate measurements of magnetic reconnection. This study compares the latitudes of spectral width boundaries (SWBs) measured by different beams of the Goose Bay radar of the Super Dual Auroral Radar Network (SuperDARN), with the latitudes of OCBs determined using the low-altitude Defense Meteorological Satellite Program (DMSP) spacecraft, in order to determine whether the accuracy of the SWB as a proxy for the ionospheric projection of the OCB depends on the line-of-sight direction of the radar beam. The latitudes of SWBs and OCBs were identified using automated algorithms applied to 5 years (1997–2001) of data measured in the 1000–1400 magnetic local time (MLT) range. Six different Goose Bay radar beams were used, ranging from those aligned in the geomagnetic meridional direction to those aligned in an almost zonal direction. The results show that the SWB is a good proxy for the OCB in near-meridionally-aligned beams but becomes progressively more unreliable for beams greater than 4 beams away from the meridional direction. We propose that SWBs are identified at latitudes lower than the OCB in the off-meridional beams due to the presence of high spectral width values that result from changes in the orientation of the beams with respect to the gradient in the large-scale ionospheric convection pattern. Keywords. Ionosphere (Instruments and techniques; Plasma convection) – Magnetospheric physics (Magnetopause, cusp and boundary layers)