LPTV-Aware Bit Loading and Channel Estimation in Broadband PLC for Smart Grid

Power line communication (PLC) has received steady interest over recent decades because of its economic use of existing power lines, and is one of the communication technologies envisaged for Smart Grid (SG) infrastructure. However, power lines are not designed for data communication, and this brings unique challenges for data communication over power lines. In particular for broadband (BB) PLC, the channel exhibits linear periodically time varying (LPTV) behavior synchronous to the AC mains cycle. This is due to the time varying impedances of electrical devices that are connected to the power grid. Another challenge is the impulsive noise in addition to power line background noise, which is due to switching events in the power line network. In this work, we focus on two major aspects of an orthogonal frequency division multiplexing (OFDM) system for BB PLC LPTV channels; bit and power allocation, and channel estimation (CE). First, we investigate the problem of optimal bit and power allocation, in order to increase bit rates and improve energy efficiency. We present that the application of a power constraint that is averaged over many microslots can be exploited for further performance improvements through bit loading. Due to the matroid structure of the optimization problem, greedy-type algorithms are proven to be optimal for the new LPTV-aware bit and power loading. Significant gains are attained especially for poor (i.e. high attenuation) channel conditions, and at reduced transmit-power levels, where the energy per bit-transmission is also low. Next, two mechanisms are utilized to reduce the complexity of the optimal LPTV-aware bit loading and peak microslot power levels: (i) employing representative values from microslot transfer functions, and (ii) power clipping. The ideas of LPTV-aware bit loading, complexity reduction mechanism, and power clipping are also applicable to non-optimal bit loading schemes. We apply these ideas to two additional sub-optimal bit loading algorithms that are based on even-like power distribution for a portion of the available spectrum, and demonstrate that similar gains in bit rates are achieved. Second, we tackle the problem of CE for BB PLC LPTV channels. We first investigate pilot based CE with different pilot geometry in order to reduce interpolation error. Block-type, comb-type, and incline type pilot arrangements are considered and a performance comparison has been made. Next we develop a robust CE scheme with low overhead that addresses the drawbacks of block-type pilot arrangement and decision directed CE schemes such as large estimation overhead for block-type pilot geometry, and difficulty in channel tracking in the case of sudden changes in the channel for decision directed approaches. In order to overcome these drawbacks, we develop a transform domain (TD) analysis approach to determine the cause of changes in the channel estimates, which are due to changes in the channel response or the presence of impulsive noise. We then propose a robust CE scheme with low estimation overhead, which utilizes pilot symbols placed widely apart and exploits the information obtained from TD analysis as a basis for switching between various CE schemes. The overhead of the proposed scheme for CE is low, and sudden changes in the channel are tracked affectively. Therefore, the effects of the LPTV channel and the impulsive noise on CE are mitigated. Our results indicate that for bit and power allocation, the proposed reduced complexity LPTV-aware bit loading with power clipping algorithm performs very close to the optimal LPTV-aware bit loading, and is an attractive solution to bit loading in a practical setting. Finally, for the CE problem, the proposed CE scheme based on TD analysis has low estimation overhead, performs well compared to block-type pilot arrangement and decision directed CE schemes, and is robust to changes in the channel and the presence of impulsive noise. Therefore, it is a good alternative for CE in BB PLC

L5 vertebrectomy for the surgical treatment of tumoral and traumatic lesions of L5 vertebra

We retrospectively reviewed the clinical characteristics and the surgical results of seven patients treated with L5 vertebrectomy. The pathologies, clinical characteristics, preoperative and postoperative radiological findings, surgical techniques, and instrumentation for seven patients operated on between 1998 and 2009 are presented in this article. Biopsies were performed on all patients except those involving trauma. Patients were followed up at three-month intervals in the first year, at 6-month intervals in the second year, and on a regular basis afterward. One patient had a traumatic L5 burst fracture; the other six had tumoral pathologies in the L5 vertebrae. One tumoral lesion was a chordoma, another was a hemangioma, and the remaining four were metastatic lesions. Radiotherapy and chemotherapy were performed for the metastatic tumor patients during the postoperative period. Patients with renal cancer and chordoma survived for 3 years; patients with lung cancer and bladder cancer survived for 1 year; and patients with breast cancer survived for 16 months. The lumbosacral region presents significant stabilization problems because of the presence of sacral slope. In our opinion, if the lesion involves only the L5 vertebra, anterior cage-filled bone cement or bone graft should be performed, as dictated by the pathology and posterior transpedicular instrumentation. If the lesion involves the L4 vertebra or the sacrum and the L5 vertebra, the instrumentation can be extended to cover other segments with sacral attachments. The present cases involved only L5 vertebra and treatment with short-segment stabilization covering the anterior and posterior columns

Revisiting stapled and handsewn loop ileostomy closures: a large retrospective series

OBJECTIVE: To compare the surgical outcomes of stapled and handsewn closures in loop ileostomies. METHODS: The data of 225 patients requiring loop ileostomies from 2002 to 2007 were retrospectively evaluated. The patients underwent partial small-bowel resections and either handsewn or stapled anastomoses for the ileostomy closures. They were followed up postoperatively with routine surgical examinations. RESULTS: The study group consisted of 124 men and 101 women with a mean age of 49.12 years. The ileostomy closure was performed with handsewn in 129 patients and with stapled in 96 patients. The mean time to the first postoperative flatus was 2.426 days in the handsewn group and 2.052 days in the stapled group (p <0.05). The mean time to the first postoperative defecation was 3.202 days in the handsewn group and 2.667 days in the stapled group (p <0.05). The mean duration of patient hospital stay was 8.581 days for the handsewn group and 6.063 days for the stapled group (p <0.05). CONCLUSIONS: Patients who underwent ileostomy closure with stapled recovered faster in the postoperative period and required shorter hospital stays than those whose closures were performed with handsewn. In our opinion, stapled should be considered the gold standard for loop ileostomy closure

Remote cerebellar hemorrhage following resection of a supratentorial tumor: a case report

Remote cerebellar hemorrhage after supratentorial surgery is rare, ranging between 0.08% and 0.29% in adults and children. However, it is extremely rare in children. This phenomenon underlying mechanisms remain obscure. A 14-year-old male child patient had a history of right focal seizures and underwent craniotomy for a left frontal mass (Dysembryoplastic Neuroepithelial Tumor). First hours post recovery period, the patient was somnolent and had right hemiparesis. Postoperative Computer Tomography and magnetic resonance imaging findings revealed that the patient had developed remote cerebellar hemorrhage. He was treated conservatively, and was free of neurological deficits

A large choroid plexus cyst diagnosed with magnetic resonance imaging in utero: a case report

The incidence of choroid plexus cysts represents approximately 1% of fetal anomalies. We describe a case in which fetal ultrasonography and fetal magnetic resonance scans were used to identify a large choroid cyst in a fetus without the use of a diagnostic amniocentesis to detect aneuploidy. After birth, the child underwent surgery. In conclusion, the nature of prenatal intracranial cysts should be fully evaluated and differentiated between choroid plexus cysts and other types of cysts. We believe that a detailed evaluation of detected cysts and other structural brain abnormalities are essential. Prenatal magnetic resonance scans clearly can decrease the need for risky procedures, such as an amniocentesis, in the evaluation of antenatal choroid plexus cysts

Unilateral Multiple Evanescent White Dot Syndrome-Like Reaction Following the CyberKnife Stereotactic Radiotherapy for Choroidal Malignant Melanoma

A 58-year-old otherwise healthy man received a diagnosis of choroidal malignant melanoma (CMM) in June 2021 and underwent a single session of (21 Gy) CyberKnife stereotactic radiotherapy (SRT). Eleven months later, we noticed 3+ anterior chamber cells with occasional vitreous cells in the left eye. Though the tumor looked regressed, there were mild optic disc leakage, early hypofluorescent and late hyperfluorescent punctate lesions scattered 360 degrees, and late staining of the mass on fluorescein angiogram. The findings were compatible with a unilateral multiple evanescent white dot syndrome (MEWDS)-like reaction that was most likely related to CyberKnife SRT-induced tumor necrosis, and a dexamethasone implant was administered intravitreally into the left eye together with topical steroids. A second intravitreal injection of dexamethasone was given three months later due to remittance of the angiographic features. As there are only a few reports on CyberKnife SRT for the treatment of CMM, we wanted to share our interesting observation of a post-treatment MEWDS-like reaction likely related to tumor necrosis syndrome with the ophthalmic community

Adjuvant Corticosteroid Therapy in Hepatosplenic Candidiasis-Related Iris

Candida infections are the most frequent infections in neutropenic patients. Hepatosplenic candidiasis (HSC) is a part of disseminated Candida infection that occurs most commonly in patients with hematologic malignancies treated with chemotherapy and requires protracted antifungal therapy. During invasive mycosis with rapid resolution of immunosuppression, immune reconstitution inflammatory syndrome (IRIS) which mimics treatment failure, drug toxicity or breakthrough infections may occur. Manifestation period, histopathologic findings and favorable effect of steroids to its inflammatory symptoms strongly suggest that HSC belongs to the invasive fungal infection induced IRIS. We present a child with B cell-acute lymphoblastic leukemia who developed HSC and addition of corticosteroid therapy to antifungal treatment achieved rapid resolution of the clinical symptoms and laboratory findings

Serum levels of TNF-α and osteoprotegerin and bone mineral density in patients with Behçet’s Disease

Objectives: Osteoporosis is commonly developed due tonatural course of Behçet’s disease (BD) and therapeuticagents. It was aimed to investigate levels of osteoprotegerinand TNF-α (tumor necrosis factor), and bone mineral density(BMD) and correlation between them in BD.Materials and methods: The study included two groupsas the study and the control group. Serum levels of TNF-α,osteoprotegerin, osteocalcine, erythrocyte sedimentation rate(ESR), C-reactive protein (CRP), and urinary creatinine anddeoxypyridinoline along with BMD level were evaluated andcompared. Correlation between TNF-α and osteoprotegerinlevel was investigated.Results: The study enrolled 41 BD patients and 36 agedmatchedcontrol subjects. Mean age was 42.26±11.64 and41.66±70.99, in the study and control groups, respectively.There was no significant difference in body mass index(BMI) of subjects between groups (p>0.05). Level of TNF-α(p<0.001), deoxypyridinoline (p<0.001) and osteocalcine(p=0.041) was significantly higher in the study group comparedto the control group. Osteoprotegerin was lower inBD patients, but the difference was not significant (p>0.05).Urinary deoxypyridinoline/ urinary creatinine ratio in patientswith BD was significantly higher than those in control group(p=0.030). Patients had significantly lower BMD comparfedto the control group, except L2-L4 vertebral area (p<0.001,p<0.001, p=0.035, p<0.001, p=0.012, p<0.001, p<0.001 andp=0.111, respectively). No correlation was found betweenTNF-α and osteoprotegerin.Conclusions: The present study indicated that TNF-α andBMD was negatively correlated with each other and TNF-αhad an effect on osteoporotic process in patients with BD.Osteoprotegerin level was not decreased, and not correlatedwith TNF-α.Key words: Behçet’s disease, osteoprotegerin, TNF-α, osteocalcin

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

Transverse Carpal Ligament and Forearm Fascia Release for the Treatment of Carpal Tunnel Syndrome Change the Entrance Angle of Flexor Tendons to the A1 Pulley: The Relationship between Carpal Tunnel Surgery and Trigger Finger Occurence

Purpose. The appearance of trigger finger after decompression of the carpal tunnel without a preexisting symptom has been reported in a few articles. Although, the cause is not clear yet, the loss of pulley action of the transverse carpal ligament has been accused mostly. In this study, we planned a biomechanical approach to fresh cadavers. Methods. The study was performed on 10 fresh amputees of the arm. The angles were measured with (1) the transverse carpal ligament and the distal forearm fascia intact, (2) only the transverse carpal ligament incised, (3) the distal forearm fascia incised to the point 3 cm proximal from the most proximal part of the transverse carpal ligament in addition to the transverse carpal ligament. The changes between the angles produced at all three conditions were compared to each other. Results. We saw that the entrance angle increased in all of five fingers in an increasing manner from procedure 1 to 3, and it was seen that the maximal increase is detected in the middle finger from procedure 1 to procedure 2 and the minimal increase is detected in little finger. Discussion. Our results support that transverse carpal ligament and forearm fascia release may be a predisposing factor for the development of trigger finger by the effect of changing the enterance angle to the A1 pulley and consequently increase the friction in this anatomic area. Clinical Relevance. This study is a cadaveric study which is directly investigating the effect of a transverse carpal ligament release on the enterance angle of flexor tendons to A1 pulleys in the hand