Determining Students’ Conceptual Understanding Level of Thermodynamics

Science students find heat, temperature, enthalpy and energy in chemical reactions to be some of the most difficult subjects. It is crucial to define their conceptual understanding level in these subjects so that educators can build upon this knowledge and introduce new thermodynamics concepts. This paper reports conceptual understanding levels of high school students of common thermodynamics subjects such as heat, temperature, enthalpy and energy changes in chemical reactions. The sample of the study was composed of 418 randomly selected students from 11 different high schools. A cross sectional survey model was employed in this study. Data were collected through the Conceptual Understanding Test (CUT), which consists of 16 questions. Cronbach's alpha reliability coefficient for the test was 0.72. Besides, interviews were conducted with 10 students to get qualitative data about their beliefs on the subject. The results of the study indicated that students’ level of conceptual understanding in thermodynamics concepts is very low. It was observed to be especially low for the concepts of (1) relationship between energy, enthalpy and bonds in chemical reactions, (2) energy and catalysts in chemical reactions, (3) changes in heat, temperature and enthalpy during change of state, and (4) the relationship between heat, temperature, mass and specific heat. Most of the students in this study do not fully understand common thermodynamics concepts although they have been studying these topics since primary school

Increased Risk of Atrial and Ventricular Arrhythmia in Long-Lasting Psoriasis Patients

Background. Several reports have demonstrated an association between psoriasis and cardiovascular diseases. P wave dispersion (PWD) is the most important electrocardiographic (ECG) markers used to evaluate the risk of atrial arrhythmias. QT dispersion (QTD) can be used to assess homogeneity of cardiac repolarization and may be a risk for ventricular arrhythmias. Aim. To search PWD and QTD in patients with psoriasis. Methods. Ninety-four outpatient psoriasis patients and 51 healthy people were evaluated by physical examination, 12-lead ECG, and transthoracic echocardiography. Severity of the psoriasis was evaluated by psoriasis area and severity index (PASI). Results. Mean disease duration was 129.4±83.9 (range, 3–360) months and PASI ranged from 0 to 34.0 (mean ± SD; 7.6±6.7). Compared to control group, psoriatic patients had significantly shorter Pmax and Pmin durations, longer QTcmax, and greater PWD and QTcD. Transmitral deceleration time (DT) and isovolumetric relaxation time (IVRT) were significantly longer among psoriasis patients. QTcD and PWD were significantly correlated with disease duration (r=0.693, P<0.001, and r=0.368, P=0.003, resp.). Conclusions. In this study, we found that both PWD and QTcD are increased in psoriasis patients compared to healthy subjects. In addition, they had longer DT and IVRT