Asymptotically optimal assignments in ordinal evaluations of proposals

Ankara : The Department of Computer Engineering and the Institute of Engineering and Science of Bilkent University, 2009.Thesis (Master's) -- Bilkent University, 2009.Includes bibliographical references leaves 42-44.In ordinal evaluations of proposals in peer review systems, a set of proposals is assigned to a fixed set of referees so as to maximize the number of pairwise comparisons of proposals under certain referee capacity and proposal subject constraints. The following two related problems are considered: (1) Assuming that each referee has a capacity to review k out of n proposals, 2 ≤ k ≤ n, determine the minimum number of referees needed to ensure that each pair of proposals is reviewed by at least one referee, (2) Find an assignment that meets the lower bound determined in (1). It is easy to see that one referee is both necessary and sufficient when k = n, and n(n-1)/2 referees are both necessary and sufficient when k = 2. It is shown that 6 referees are both necessary and sufficient when k = n/2. Furthermore it is shown that 11 referees are necessary and 12 are sufficient when k = n/3, and 18 referees are necessary and 20 referees are sufficient when k = n/4. A more general lower bound of n(n-1)/k(k-1) referees is also given for any k, 2 ≤ k ≤ n, and an assignment asymptotically matching this lower bound within a factor of 2 is presented. These results are not only theoretically interesting but they also provide practical methods for efficient assignments of proposals to referees.Atmaca, AbdullahM.S

On The Number of Unlabeled Bipartite Graphs

This paper describes a result that has been obtained in joint work with Abdullah Atmaca of Bilkent University, Ankara, TurkeyLet $I$ and $O$ denote two sets of vertices, where $I\cap O =\Phi$, $|I| = n$, $|O| = r$, and $B_u(n,r)$ denote the set of unlabeled graphs whose edges connect vertices in $I$ and $O$. It is shown that the following two-sided equality holds. $\displaystyle \frac{\binom{r+2^{n}-1}{r}}{n!} \le |B_u(n,r)| \le 2\frac{\binom{r+2^{n}-1}{r}}{n!}

Ureteric Duplication is not a Contraindication for Robot-Assisted Laparoscopic Radical Cystoprostatectomy and Intracorporeal Studer Pouch Formation

The authors found that duplicated ureters was not a contraindication to robot-assisted laparoscopic radical cystoprostatectomy in this case

What if the Hand Piece Spring Disassembles During Robotic Radical Prostatectomy?

These authors report on the successful management of a disassembled hand piece spring during robotic radical prostatectomy

The Incidence and Management of Pleural Injuries Occurring during Open Nephrectomy

Objective. To evaluate the incidence, management, and risk factors of pleural injuries occurring during open nephrectomy. Methods. Between June 2004/and June 2008, 165 patients (167 renal units) underwent open simple (n = 37, 22.2%), partial (n = 39, 23.4%) or radical (n = 91, 54.5%) nephrectomy in our institution. Results. Flank, Chevron, and abdominal midline incisions were used in 148(88.6%), 17(10.2%), and in 2(1.2%) surgical procedures, respectively. Ribs were excised in 109(65.3%) procedures (11th rib, 10th-11th ribs, and 11th-12th ribs). Intraoperative pleural injuries were detected in 20(12%) procedures, 16(80%) were treated successfully with simple evacuation technique, and 4 required chest tube insertion. Age, sex, surgery type, incision type, and surgery site were not associated with pleural injury occurrence (P > .05). Rib resection was the only parameter associated with pleural injury occurrence. Conclusion. Pleural injuries occur in 12% of open nephrectomy procedures, and 80% can be repaired successfully. Few of them (2.4%) need chest tube insertion. Performing rib resection is a significant risk factor for pleural injury occurrence during nephrectomies

Retroperitoneal Extragonadal Nonseminomatous Germ Cell Tumor with Synchronous Orbital Metastasis

A huge retroperitoneal tumor with a right orbital mass was detected and proved to be an extragonadal nonseminomatous germ cell tumor on biopsy. BEP chemotherapy caused some regression in orbital mass however no change in retroperitoneal tumor size as well as serum tumor marker levels occurred. Herein, we present a rarely seen entity of extragonadal retroperitoneal nonseminomatous germ cell tumor with synchronous orbital metastases and discuss its diagnosis and management

Is Positron Emission Tomography Reliable to PredictPost-Chemotherapy Retroperitoneal Lymph NodeInvolvement in Advanced Germ Cell Tumors of theTestis?

PURPOSE: To evaluate if 18 fluorodeoxyglucose positron emission tomography(18FDG-PET) scan could identify post-chemotherapy retroperitoneal lymphnode (RPLN) involvement in advanced germ cell tumors of the testis.MATERIALS AND METHODS: Between January 2005 and January 2009, 16patients with advanced germ cell tumors of the testis underwent RPLNdissection (RPLND) following chemotherapy. Before RPLND, abdominalcomputed tomography (CT), magnetic resonance imaging (MRI), and18FDG-PET were performed in all the patients. Findings on 18FDG-PETwere compared with pathological evaluation of the removed lymphatic tissue.RESULTS: Both abdominal CT and MRI demonstrated retroperitonealmasses in all the patients following chemotherapy. Although PET did not demonstrate any activity in 8 patients, tumor was detected histopathologically.In 1 patient, 18FDG-PET demonstrated activity; however, no tumor wasdetected on pathology. Of the remaining 7 patients, 18FDG-PET findingswere concordant with the histopathological findings. No activity wasdetected in 2 patients with no tumors whereas all 5 patients harboring viabletumor cells showed positive 18FDG-PET activity. In our study, sensitivityand specificity of 18FDG-PET in detecting RPLN involvement were detectedto be 39% and 67%, respectively.CONCLUSION: 18FDG-PET imaging does not seem to be a reliable methodin detecting RPLN involvement in advanced germ cell tumors of the testisfollowing chemotherapy. Therefore, we neither recommend routine use of18FDG-PET scanning nor decide the treatment work-up by solely relying onthe 18FDG-PET findings in this patient group