Anomalous field-dependent specific heat in charge-ordered Pr1−x_{1-x}Cax_xMnO3_3 and La0.5_{0.5}Ca0.5_{0.5}MnO3_3

We report low temperature specific heat measurements of Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ ($0.3\leq x \leq 0.5$) and La$_{0.5}$Ca$_{0.5}$MnO$_{3}$ with and without applied magnetic field. An excess specific heat, $C^{\prime}(T)$, of non-magnetic origin associated with charge ordering is found for all the samples. A magnetic field sufficient to induce the transition from the charge-ordered state to the ferromagnetic metallic state does not completely remove the $C^{\prime}$ contribution. This suggests that the charge ordering is not completely destroyed by a "melting" magnetic field. In addition, the specific heat of the Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ compounds exhibit a large contribution linear in temperature ($\gamma T$) originating from magnetic and charge disorder.Comment: submitted to PRL 5 pages, 3 figures include

Structural and doping effects in the half-metallic double perovskite A2A_2CrWO6_6

he structural, transport, magnetic and optical properties of the double perovskite $A_2$CrWO$_6$ with $A=\text{Sr, Ba, Ca}$ have been studied. By varying the alkaline earth ion on the $A$ site, the influence of steric effects on the Curie temperature $T_C$ and the saturation magnetization has been determined. A maximum $T_C=458$ K was found for Sr$_2$CrWO$_6$ having an almost undistorted perovskite structure with a tolerance factor $f\simeq 1$. For Ca$_2$CrWO$_6$ and Ba$_2$CrWO$_6$ structural changes result in a strong reduction of $T_C$. Our study strongly suggests that for the double perovskites in general an optimum $T_C$ is achieved only for $f \simeq 1$, that is, for an undistorted perovskite structure. Electron doping in Sr$_2$CrWO$_6$ by a partial substitution of Sr$^{2+}$ by La$^{3+}$ was found to reduce both $T_C$ and the saturation magnetization $M_s$. The reduction of $M_s$ could be attributed both to band structure effects and the Cr/W antisites induced by doping. Band structure calculations for Sr$_2$CrWO$_6$ predict an energy gap in the spin-up band, but a finite density of states for the spin-down band. The predictions of the band structure calculation are consistent with our optical measurements. Our experimental results support the presence of a kinetic energy driven mechanism in $A_2$CrWO$_6$, where ferromagnetism is stabilized by a hybridization of states of the nonmagnetic W-site positioned in between the high spin Cr-sites.Comment: 14 pages, 10 figure

Essential Experimental Methods for Identifying Bonghan Systems as a Basis for Korean Medicine: Focusing on Visual Materials from Original Papers and Modern Outcomes

In the 1960s, through studies on Korean Medicine, Bonghan Kim proposed the Bonghan systems (BS) as the anatomical reality of the acupuncture meridians based on various experimental data. Since 2002, several groups, mainly led by a team at Seoul National University, who renamed the BS as the primo vascular system (PVS), have published around 70 papers showing biological structures corresponding to the BS. However, it is still difficult for other researchers to find them, especially under the skin, which Bonghan Kim first reported as acupuncture points, due to similar-looking biological tissues, for example, the lymphatic vessels, and such artifacts as blood clots or fascia debris. To solve these drawbacks, we examined the main methods for identifying the BS by comparing the original papers with the modern outcomes in terms of the common physical/chemical characteristics of the BS. In addition, effective methods of staining and microscopic observations discovered by modern teams are synthetically explained using visual materials such as diagrams and photos. Through the essentially organized methods in this review paper, we suggest that one can find the BS under the skin as putative acupuncture points by tracing the intraexternal BS, from which a new Korean Medicine will be born

Complications and Socioeconomic Costs Associated With Falls in the Elderly Population

ObjectiveTo explore the incidence, characteristics, complications and socioeconomic impacts associated with falls in community-dwelling elderly.MethodsFrom September 1, 2015 to October 12, 2015, a questionnaire-based survey was conducted involving a total of 2,012 elderly who lived in Guro-gu (Seoul), Yeongdeungpo-gu (Seoul), Yangpyeong-gu (Gyeonggi-do), Dalseong-gu (Daegu), and Jung-gu (Daegu). The subjects were interviewed using a structured questionnaire to obtain demographic characteristics and comprehensive falling histories. The socioeconomic cost related to falls was estimated using the statistical data provided by the Health Insurance Review and Assessment Service.ResultsFalls were recorded in 666 out of the 2,012 subjects (33.1%) during the past year. Frequent falls occurred during December, in the afternoons, when the floor was slippery. The most common injuries included the low back and the most common injury type was sprain. The total direct costs related to falls involving the 2,012 subjects were 303,061,019 KRW (Korean won). The average medical cost related to falls in the 2,012 subjects was 150,627 KRW and the average medical cost of 666 subjects who experienced falls was 455,047 KRW. Estimates of the total population over the age of 60 years showed that the annual direct costs associated with falls in Korea over the age of 60 years were about 1.378 trillion KRW.ConclusionThis study was conducted to explore the incidence, characteristics, complications, and socioeconomic impacts of falls in community-dwelling elderly. This study is expected to be used as a source of basic data for the establishment of medical policy for the elderly and the development of a fall prevention program for the elderly in Korea

Expression Patterns of Tumor Markers in Liver Transplant Recipients Showing Complete Pathological Response of Hepatocellular Carcinoma

Complete pathological response (CPR) is achieved with various pretransplant locoregional treatments for hepatocellular carcinoma (HCC). This study aimed to investigate pretransplant expression of HCC tumor markers in liver transplantation (LT) recipients showing CPR. For the CPR group, 166 patients were selected from a single-institution LT database. Two control groups of 332 patients without HCC and 184 patients with partial pathological response (PPR) were also selected. The model for end-stage liver disease score in the CPR group was 11.5 ± 7.7. The number of transcatheter arterial chemoembolization sessions before LT was one in 68 patients (14.0%), two in 38 patients (22.9%), and three or more in 60 patients (36.1%). A solitary non-viable tumor was identified in 120 (86.4%) of the explant livers and the largest tumor size was 2.4 ± 1.3 cm. Living-donor and deceased-donor LTs were performed in 152 (91.6%) and 14 (8.4%) patients, respectively. The median levels of α-fetoprotein (AFP) and protein induced by Vitamin K absence or antagonist-II (PIVKA-II) measured within two weeks before LT were 4.2 ng/mL and 20 mAU/mL, respectively. These tumor marker levels were comparable to those in the no-HCC control group, but much lower than those in the PPR group (p p < 0.001). In conclusion, the present study results suggest that normalizing AFP and PIVKA-II after locoregional treatment is indicative of CPR. However, some CPR patients showed high expression of tumor markers; thus, pretransplant values of HCC tumor markers should be interpreted with caution