Adaptive data rate control TDMA systems as a rain attenuation compensation technique

Rainfall attenuation has a severe effect on signal strength and impairs communication links for future mobile and personal satellite communications using Ka-band and millimeter wave frequencies. As rain attenuation compensation techniques, several methods such as uplink power control, site diversity, and adaptive control of data rate or forward error correction have been proposed. In this paper, we propose a TDMA system that can compensate rain attenuation by adaptive control of transmission rates. To evaluate the performance of this TDMA terminal, we carried out three types of experiments: experiments using a Japanese CS-3 satellite with Ka-band transponders, in house IF loop-back experiments, and computer simulations. Experimental results show that this TDMA system has advantages over the conventional constant-rate TDMA systems, as resource sharing technique, in both bit error rate and total TDMA burst lengths required for transmitting given information

Carotid Artery Revascularization Improves Cardiac Sympathetic Nerve Activity in Patients With Carotid Artery Stenosis

Background: The carotid sinus baroreceptor reflex controls the neural regulation of blood pressure. Baroreceptor disorders due to carotid sinus atherosclerosis have detrimental cardiovascular effects. This study investigated the medium-term effects of carotid artery revascularization (CAR) on sympathetic and cardiac function and systemic blood pressure variability in patients with carotid artery stenosis.Methods: This study included 21 consecutive patients (median age 70 years, 18 men) with carotid artery stenosis scheduled for CAR. 123I metaiodobenzylguanidine (MIBG) scintigraphy, echocardiography, brain natriuretic peptide levels, 24-h Holter electrocardiography (ECG), and ambulatory blood pressure monitoring assessed approximately 3 months postoperatively were compared to preoperative data.Results: All 21 enrolled patients underwent CAR. Carotid artery stenting was done in three patients with cardiovascular risk or anatomical difficult for carotid endarterectomy. The mean common carotid artery end-diastolic velocity improved significantly (P < 0.01) by 1.6-fold, from 10.8 ± 3.2 to 16.1 ± 7.1 cm/s. In 123I-MIBG scintigraphy, the heart-to-mediastinum (H/M) count ratio was significantly higher than preoperatively (from 2.66 ± 0.48 to 2.86 ± 0.56, P = 0.03). Holter ECG analysis revealed a significant decrease in the low-frequency/high-frequency (LF/HF) ratio compared to preoperatively (from 2.17 ± 1.20 to 1.62 ± 0.68, P = 0.04). These findings suggest decreased myocardial sympathetic activation. In echocardiography, the tissue Doppler-derived e’ increased, and E/e’ decreased significantly (P < 0.05) from 11.7 ± 5.1 to 10.1 ± 4.0, suggesting an improved left ventricular diastolic capacity. The mean 24-h and nighttime blood pressures were unchanged.Conclusions: CAR in patients with carotid stenosis may provide medium-term improvement in cardiac sympathetic nerve activity and left ventricular diastolic dysfunction

Thrombosed sinus of Valsalva aneurysm masquer ading as a cardiac tumour: A case report

BackgroundAn aortic sinus of Valsalva aneurysm (SVA) often remains undiagnosed until it ruptures. An SVA filled with thrombus can be challenging to diagnose accurately.Case summaryA 70-year-old man was admitted with a clinical diagnosis of well-tolerated complete atrioventricular block (AVB). Transthoracic echocardiography revealed a spherical mass (43 × 49 mm) at the interatrial septum. Enhanced computed tomography (CT) showed a well-defined, hollow, and non-enhanced mass suggesting a cardiac tumour. However, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) showed no uptake in the mass. After implantation of a permanent pacemaker, anticoagulant therapy was started for paroxysmal atrial fibrillation. Two months later, follow-up evaluation by echocardiography and enhanced CT revealed an increase in size of the hollow interior cavity, suggesting thrombolysis by the anticoagulant. We diagnosed a non-coronary SVA filled with thrombus, which masqueraded as a cardiac tumour and may have caused complete AVB.ConclusionsWe describe a rare case of a giant thrombosed SVA masquerading as a cardiac tumour. Initial 18F-FDG PET/CT and serial imaging studies were helpful in distinguishing it from a cardiac tumour

Utility of Superb Microvascular Imaging in the Assessment of Foot Perfusion in Patients with Critical Limb Ischemia

(1) Background: Although the ankle–brachial index (ABI) and skin perfusion pressure (SPP) are commonly used to evaluate the peripheral circulation in critical limb ischemia (CLI), they often cannot be performed on sore areas. We investigated the utility of superb microvascular imaging (SMI) for assessing foot perfusion in CLI patients.(2) Methods: We measured the SMI-based vascular index (SMI-VI) at six sites in the foot before and after endovascular treatment (EVT) in 50 patients with CLI who underwent EVT of the superficial femoral artery and compared the results with SPP values and the ABI.(3) Results: SMI visualized foot perfusion in all subjects in accordance with the angiosome, including the toe areas, while the ABI was unmeasurable in three patients on hemodialysis and SPP failed in four patients. SMI-VI values were significantly lower in the CLI group than in controls, and the plantar SMI-VI had the highest diagnostic performance for CLI (sensitivity 88.6%, specificity 95.6%). After EVT, the increase in the SMI-VI was positively correlated with the increase in SPP but not that in the ABI, implying that the SMI-VI reflects foot microcirculation. (4) Conclusions: SMI enables the visualization and quantification of foot microcirculation based on the angiosome. SMI has high utility as a tool for assessing foot perfusion in CLI

Early development and neurogenesis of Temnopleurus reevesii

Sea urchins are model non-chordate deuterostomes, and studying the nervous system of their embryos can aid in the understanding of the universal mechanisms of neurogenesis. However, despite the long history of sea urchin embryology research, the molecular mechanisms of their neurogenesis have not been well investigated, in part because neurons appear relatively late during embryogenesis. In this study, we used the species Temnopleurus reevesii as a new sea urchin model and investigated the detail of its development and neurogenesis during early embryogenesis. We found that the embryos of T. reevesii were tolerant of high temperatures and could be cultured successfully at 15–30°C during early embryogenesis. At 30°C, the embryos developed rapidly enough that the neurons appeared at just after 24 h. This is faster than the development of other model urchins, such as Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus. In addition, the body of the embryo was highly transparent, allowing the details of the neural network to be easily captured by ordinary epifluorescent and confocal microscopy without any additional treatments. Because of its rapid development and high transparency during embryogenesis, T. reevesii may be a suitable sea urchin model for studying neurogenesis. Moreover, the males and females are easily distinguishable, and the style of early cleavages is intriguingly unusual, suggesting that this sea urchin might be a good candidate for addressing not only neurology but also cell and developmental biology

A High-Speed Congenic Strategy Using First-Wave Male Germ Cells

BACKGROUND: In laboratory mice and rats, congenic breeding is essential for analyzing the genes of interest on specific genetic backgrounds and for analyzing quantitative trait loci. However, in theory it takes about 3-4 years to achieve a strain carrying about 99% of the recipient genome at the tenth backcrossing (N10). Even with marker-assisted selection, the so-called 'speed congenic strategy', it takes more than a year at N4 or N5. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe a new high-speed congenic system using round spermatids retrieved from immature males (22-25 days of age). We applied the technique to three genetically modified strains of mice: transgenic (TG), knockin (KI) and N-ethyl-N-nitrosourea (ENU)-induced mutants. The donor mice had mixed genetic backgrounds of C57BL/6 (B6):DBA/2 or B6:129 strains. At each generation, males used for backcrossing were selected based on polymorphic marker analysis and their round spermatids were injected into B6 strain oocytes. Backcrossing was repeated until N4 or N5. For the TG and ENU-mutant strains, the N5 generation was achieved on days 188 and 190 and the proportion of B6-homozygous loci was 100% (74 markers) and 97.7% (172/176 markers), respectively. For the KI strain, N4 was achieved on day 151, all the 86 markers being B6-homozygous as early as on day 106 at N3. The carrier males at the final generation were all fertile and propagated the modified genes. Thus, three congenic strains were established through rapid generation turnover between 41 and 44 days. CONCLUSIONS/SIGNIFICANCE: This new high-speed breeding strategy enables us to produce congenic strains within about half a year. It should provide the fastest protocol for precise definition of the phenotypic effects of genes of interest on desired genetic backgrounds

White matter integrity, executive dysfunction, and processing speed in amyotrophic lateral sclerosis

Cognitive impairment in amyotrophic lateral sclerosis (ALS) is characterized by deficits on tests of executive functions however the contribution of processing speed is unknown. By contrast, multiple sclerosis (MS) is a disorder in which slowed processing speed is regarded as the core deficit, however, methodology is often confounded by tasks which depend on motor speed. MRI studies have revealed multi-system cerebral involvement in ALS, with evidence of reduced white matter volume and integrity in predominantly frontotemporal regions. The current study had two aims. Firstly, to investigate whether cognitive impairments in ALS and MS are due to executive dysfunction or slowed processing speed, independent of motor dysfunction. Secondly, to investigate the relationship between specific cognitive impairments and the integrity of distinct white matter tracts in ALS. Twenty-nine ALS patients, twenty-five MS patients, and matched healthy control groups were administered a dual task paradigm and processing speed tasks in which stimulus presentation times were manipulated. In addition background measures of executive functioning, working memory, verbal memory, and language were administered. White matter integrity was investigated using region-of-interest (ROI) and tract based spatial statistics (TBSS) analyses of diffusion MRI data. ALS patients did not show impairments in tests of processing speed, but deficits were revealed in the dual task, as well as background tests of executive functioning, working memory, and verbal memory. MS patients also exhibited deficits in the dual task as well as background tests of executive functioning, working memory, and verbal memory. However, in contrast to ALS patients, a processing speed deficit was also observed in MS. ROI analyses revealed significant differences in fractional anisotropy (FA) and mean diffusivity () between ALS patients and healthy controls. Reduced integrity was observed in the corticospinal tracts and prefrontal and temporal white matter tracts including uncinate fasciculus, inferior longitudinal fasciculus, and regions of the cingulum. Significant differences also emerged in the white matter underlying the superior, medial and inferior frontal gyri, and the temporal gyri. Similar group differences were found in the TBSS analyses; ALS patients displayed prominent changes in the corticospinal tract and corpus callosum as well as extensive changes in prefrontal and temporal tracts and association fibres. Correlations between task performance and ROI parameters revealed that dual task performance was associated with FA in the middle frontal gyrus white matter while letter fluency indices correlated with FA in the corpus callosum and corticospinal tracts. Furthermore, verbal memory performance correlated with FA in the inferior longitudinal fasciculus and working memory performance correlated with in uncinate fasciculus and hippocampal portion of the cingulum. Correlations with TBSS revealed significant associations between letter fluency indices and FA in the corticospinal tracts and anterior corpus callosum. The current study demonstrates that cognitive impairment in ALS is not due to slowed processing speed. Moreover dual task deficits are related to distinct prefrontal tract involvement in ALS, whilst fluency deficits may reflect decreasing callosal integrity. Deficits in working memory and verbal memory are related to white matter changes in fibre bundles connecting prefrontal, temporal, and limbic structures

Thin Film Growth and Device Fabrication of Iron-Based Superconductors

Iron-based superconductors have received much attention as a new family of high-temperature superconductors owing to their unique properties and distinct differences from cuprates and conventional superconductors. This paper reviews progress in thin film research on iron-based superconductors since their discovery for each of five material systems with an emphasis on growth, physical properties, device fabrication, and relevant bulk material properties.Comment: To appear in J. Phys. Soc. Jp