Prestressed concrete beams with stirrups subjected to torsion, bending and shear

Reported in this thesis are test results of 37 eccentrically prestressed beams with stirrups. Single variable parameters were investigated including the prestressing force, the prestressing steel area, the concrete strength, the aspect ratio h/b and the stirrups size and spacing. Interaction of bending, torsion and shear was also investigated by testing a series of beams subjected to varying bending/torsional moment ratios. For the torsional strength an empirical expression of linear format is proposed and can be rearranged in a non-dimensional interaction form: T/To+V/Vo+M/Mo+Ps/Po+Fs/Fo=Pc2/Fsp. This formula which is based on an average experimental steel stress lower than the yield point is compared with 243 prestressed beams containing ' stirrups, including the author's test beams, and good agreement is obtained. For the theoretical analysis of the problem of torsion combined with bending and shear in concrete beams with stirrups, the method of torque-friction is proposed and developed using an average steel stress. A general linear interaction equation for combined torsion with bending and/or shear is proposed in the following format: (fi) T/Tu=1 where (fi) is a combined loading factor to modify the pure ultimate strength for differing cases of torsion with bending and/or shear. From the analysis of 282 reinforced and prestressed concrete beams containing stirrups, including the present investigation, good agreement is obtained between the method and the test results. It is concluded that the proposed method provides a rational and simple basis for predicting the ultimate torisional strength and may also be developed for design purposes.

Scrotal Exploration for Testicular Torsion and Testicular Appendage Torsion: Emergency and Reality

Background: Scrotal exploration is considered the procedure of choice for acute scrotum. Objectives: We evaluated the importance of early diagnosis and testicular salvage on the therapeutic outcomes of patients with pediatric testicular torsion (TT) and testicular appendage torsion (TAT) in our geographic area. Patients and Methods: We performed a retrospective database analysis of patients who underwent emergency surgery for TT or TAT between January 1996 and June 2009. Patient history, physical examination findings, laboratory test results, color Doppler sonography (CDS) results, and surgical findings were reviewed. Results: A total of 65 cases were included in our analysis. Forty-two cases were followed up for at least 3 months. Testicular tenderness was identified as the major clinical manifestation of TT, while only a few patients with TAT presented with swelling. CDS was an important diagnostic modality. The orchiectomy rate was 71% in the TT group. Conclusions: Cases of acute scrotum require attention in our area. Early diagnosis and scrotal exploration could salvage the testis or preserve normal function without the need for surgery.

Outcomes of Second Look Exploration in Testicular Torsion of Children

Background: Testicular torsion (TT), or twisting of the testicle resulting in a strangulation of the blood supply, occurs in men whose tissue surrounding the testicle is not well attached to the scrotum. It is important to emphasize that testicular torsion is a medical emergency. Objectives: The aim of this study is to evaluate the second look exploration and outcomes in TT. Patients and Methods: Seventy boys out of 124 patients underwent early exploration and 48 hours later second look exploration due to TT. All patients were checked with preoperative color-doppler ultrasonography (CDU) and intraoperative bleeding test. Data included age at admission, side of pathology, relation of TT with season of year, duration of preoperative history, degree of testicular torsion, CDU findings, and degree of bleeding; results of second look exploration, follow-up, and outcomes were analyzed. Results: Totally 70 patients were included in this study within five years, of which mean age was 28.6 ± 32.9 months (range 1 to 144), 48% of our patients had nausea and vomiting. Preoperative CDU showed absent/weak flow in 50 (71%) cases. Winter showed most frequently (44%) referred cases of testicular torsion. Orchidopexy was performed in 44 (63%) and orchidectomy in 26 (37%) cases after second look exploration. Mean follow-up duration was 3.1 ± 1.4 years. 4 (9%) cases in orchidopexy group developed testicular atrophy during follow-up, all four cases had a history of longer than 12 hours and grade II testicular bleeding test intra-operatively. Other orchidopexy patients salvaged. 26 patients, who were in grade III, underwent orchidectomy in second look exploration. Conclusions: TT requires emergency attention. The ischemia time of the testis is traditionally after 6 hours, and imaging or other diagnostic modality should not be a cause of delay. Early surgical exploration is modality of choice, and second look exploration after 48 hours can be more effective and salvageable in these patients.

A Novel Range Test

In a range test, one party holds a ciphertext and needs to test whether the message encrypted in the ciphertext is within a certain interval range. In this paper, a range test protocol is proposed, where the party holding the ciphertext asks another party holding the private key of the encryption algorithm to help him. These two parties run the protocol to implement the test. The test returns TRUE if and only if the encrypted message is within the certain interval range. If the two parties do not conspire, no information about the encrypted message is revealed from the test except what can be deduced from the test result. Advantages of the new protocol over the existing related techniques are that it achieves correctness, soundness, °exibility, high e±ciency and privacy simultaneously.