Heat Sink Effect on Tumor Ablation Characteristics as Observed in Monopolar Radiofrequency,Bipolar Radiofrequency,and Microwave,Using Ex Vivo Calf Liver Model

Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.     

The Relationship between College Graduate’s Dual Self-Consciousness and Job Search Clarity: The Mediating Role of Perceived Stress

The aim of the study was to explore the relationship between college graduates’ dual self-consciousness, job search clarity and perceived stress, and reveal the mediating role of perceived stress between dual self-consciousness and job search clarity. In this study, 467 college graduates were investigated using the Dual Self-Consciousness Scale, Job Search Clarity Scale, and Perceived Stress Scale. After controlling for gender, age, and region, the results revealed that: (1) private self-consciousness has a significant positive predictive effect on job search clarity; (2) perceived stress has a significant negative predictive effect on job search clarity; (3) perceived stress plays partial mediation effects between private self-consciousness and job search clarity; (4) perceived stress plays complete mediation effects between public self-consciousness and job search clarity; (5) perceived stress has suppressing effects between public self-consciousness and job search clarity.     

A noninvasive, in vivo model for studying strain adaptive bone modeling

We present a noninvasive, in vivo model for strain application in the tibiae of rats. The hind limb of each animal was placed into a device that applied four point bending to the tibia. Bending was applied in the medial-lateral direction causing compression on the lateral surface of the tibia and tension on the anteromedial surface. The peak strain magnitudes were estimated to be between 1600 and 3500 mu strain. In this pilot work, data were collected from 12 rats. The rats received either one cycle per day, four cycles per day, 12 cycles per day, 36 cycles per day, or 108 cycles per day of bending. The experimental (right) tibiae from all of the rats showed new bone formation after 12 days. The control (left) tibiae showed no new bone formation over this period. A better organized, dense bony reaction occurred in regions of lesser strains than in regions of higher strains, where there was a large accumulation of bone easily identified as woven. The organization and density of the newly formed bone appeared to be inversely related to the peak strains in the region. After 40 days of daily loading, the new bone area appeared to be more compact and better mineralized. However, bone formation was still occurring after 40 days. The results of this study suggest that woven bone formation occurred due to the bending stimulus and not due to pathology.     

Menstrual Perceptions and Preparation Among Female Adolescents

Seventy-four 8th- and 10th-grade students attending a private girls' school in Hawaii were queried about their perceptions of and preparation for menstruation using a questionnaire administered in a health education class. Eighty percent had already started menstruating. The most frequently cited perceptions by the respondents referred to both the inconveniences and the normalcy of menstruation. Many were first informed about menstruation by their mothers and stated that they also first informed their mothers when they started menstruating. Surprise, fear, and embarrassment were common initial reactions, while strong negative or positive emotions were more rare. Only 35% wanted boys and girls together during class discussion, but 89% stated that boys needed to be informed about menstruation. The most frequent reasons cited for noncoed settings were the girls' concern about their comfort in openly discussing menstruation. Thirty-eight percent thought parents should inform other siblings when they started menstruation, although almost half gave specific conditions the parents should consider. The majority thought the fifth to sixth grades were the best times to introduce menstruation content.