Assessing monthly average solar radiation models: a comparative case study in Turkey.

Solar radiation data are required by solar engineers, architects, agriculturists, and hydrologists for many applications such as solar heating, cooking, drying, and interior illumination of buildings. In order to achieve this, numerous empirical models have been developed all over the world to predict solar radiation. The main objective of this study is to examine and compare 147 solar radiation models available in the literature for the prediction of monthly solar radiation at Ankara (Turkey) based on selected statistical measures such as percentage error, mean percentage error, root mean square error, mean bias error, and correlation coefficient.

A polymer with a benzo[2,1-b;3,4-b']dithiophene moiety for photovoltaic applications.

The characterization of a benzo[2,1-b;3,4-b']dithiophene containing conjugated polymer (PBTT) is demonstrated, with regard to its photovoltaic performance. X-ray diffraction measurements reveal that the thermal treatment results in an increased crystallinity within the PBTT:[70]PCBM network and subsequent spatial rearrangement in the film. Upon stepwise annealing, the PBTT-based bulk-heterojunction solar cells show an overall conversion efficiency of 2.

[Peri- and postoperative pain therapy with mechanical patient-controlled disposable analgesia pumps in general surgery. Report of initial trial].

The patient-controlled analgesia (PCA) or "ondemand analgesia" is a pain-relieving therapy, which is regulated and monitored by the patient himself. Postoperative pain therapy is the main approach for PCA, which facilitates a long-term, individually controlled pain relief. In certain situations we use mechanical PCA-pumps filled with piritramid (Dipidolor) as an opioid-analgetic for reducing postoperative pain.

[Percutaneous transluminal angioplasty (PTA) of the arteries of the arm in brachial and cerebral ischemia].

35 patients with brachial and/or cerebral ischemia underwent 37 PTA's. Indications for PTA were stenosis (n = 31) or occlusion (n = 1) of the subclavian artery, stenosis of the brachiocephalic trunk (n = 2), stenosis of the axillary artery (n = 2) and stenosis of the brachial artery (n = 1). 23 patients demonstrated a subclavian steal phenomenon.