Mean Loss Rate Research Articles

Size-based hydroacoustic measures of within-season fish abundance in a boreal freshwater ecosystem.

Eleven sequential size-based hydroacoustic surveys conducted with a 200 kHz split-beam transducer during the summers of 2011 and 2012 were used to quantify seasonal declines in fish abundance in a boreal reservoir in Manitoba, Canada. Fish densities were sufficiently low to enable single target resolution and tracking. Target strengths converted to log2-based size-classes indicated that smaller fish were consistently more abundant than larger fish by a factor of approximately 3 for each halving of length. For all size classes, in both years, abundance (natural log) declined linearly over the summer at rates that varied from -0.067.day-1 for the smallest fish to -0.016.day-1 for the largest (R2 = 0.24–0.97). Inter-annual comparisons of size-based abundance suggested that for larger fish (>16 cm), mean winter decline rates were an order of magnitude lower (-0.001.day-1) and overall survival higher (71%) than in the main summer fishing season (mean loss rate -0.038.day-1; survival 33%). We conclude that size-based acoustic survey methods have the potential to assess within-season fish abundance dynamics, and may prove useful in long-term monitoring of productivity and hence management of boreal aquatic ecosystems.

Implant Stability Measurements in the Long-Term Follow-up of Dentis Implants: A Retrospective Study With Periotest.

The purpose of this study was to evaluate retrospectively the stability of Dentis implant with the Periotest. In total, 36 patients and 88 implants were investigated. Periotest was used to measure implant stability, and a periapical view was taken immediately after surgery and again immediately after, 3 months after, 6 months and 5 years after prosthesis placement. Bone loss on the periapical view, bone quality according to tactile sensation, and area of implant installation were assessed. The mean Periotest value (PTV) immediately after surgery was -1.02, and the mean bone loss rate (bone loss/fixture length × 100) at 6 months after prosthesis placement was 8.42%. PTV was higher with more bone loss (types III, IV vs types I, II bone). The lowest mean PTV was in the lower molar area (-1.48), followed by the lower anterior (-1.41), upper molar (0.11), and upper anterior area (5). One implant failed and survival rates were 98.9%. Implant stability was lower in cases with more bone loss and poor bone quality and in the maxilla versus the mandible.

Influence of the difficulty of graft unfolding and attachment on the outcome in Descemet membrane endothelial keratoplasty.

Descemet membrane endothelial keratoplasty (DMEK) is a standard procedure in patients with endothelial corneal disorders. We investigated the difficulty of unfolding and attaching the graft lamella and its correlation to characteristics of the graft lamella donor, preoperative patient characteristics, and the postoperative outcome. After preparation of the graft lamella, we prospectively graded the unfolding of the graft lamella in 169 consecutive DMEK procedures between September 2012 and August 2013 at the Charité-Universitätsmedizin Berlin with four different grades. Various donor characteristics and preoperative patient characteristics were analyzed and correlated to the grading. Additionally, visual acuity, corneal thickness and endothelial cell density were measured and correlated. Donor characteristics (age [range, 49 - 79 years], gender, endothelial cell density, total storage time, storage de-swelling time, postmortem time) did not correlate to the grading. Preoperative visual acuity significantly influenced the grade of unfolding and attaching of the graft lamella (p = 0.023), while all other preoperative parameters (age, gender, indication for DMEK, preoperative endothelial cell density and preoperative central corneal thickness) showed no correlation. Visual acuity improved significantly after surgery (p < 0.001, preoperative 0.73 ± 0.43 LogMAR versus 0.31 ±0.28 LogMAR after one month, 0.25 ± 0.29 LogMAR after three months, and 0.21 ± 0.25 LogMAR after six months). Visual acuity did not differ significantly between the grading groups at any time point postoperatively. After 6 months, the mean loss rate of endothelial cell density was 24.7 %. Grading group IV developed significantly higher endothelial loss after one month, after three months and after six months compared to the other groups (p = 0.039, p = 0.008, p = 0.048). Graft detachment requiring an additional intracameral air injection to fix the graft detachment (re-bubbling) occurred in 61 eyes (38.1 %). In eyes graded IV, more re-bubblings were necessary than in all other groups (grade I: 37.0 %; grade II: 44.7 %; grade III: 43.8 %; grade IV: 50.0 %; p = 0.128; df = 3; χ (2) = 5.676). There is no correlation between corneal donor tissue characteristics and the degree of difficulty of unfolding using graft lamella older than 49 years. Therefore, it is not possible to select grafts best suited for DMEK surgery on the basis of donor characteristics when the donor age is above 50 years. Preoperative visual acuity influences the grade of difficulty. The rate of graft detachments and endothelial cell loss increases significantly with a more difficult graft unfolding. The proposed grading system may therefore be relevant for postoperative management.

A new approach to estimate the in situ fractional degradation rate of organic matter and nitrogen in wheat yeast concentrates

In the classic in situ method, small particles are removed during rinsing and hence their fractional degradation rate cannot be determined. A new approach was developed to estimate the fractional degradation rate of nutrients in small particles. This approach was based on an alternative rinsing method to reduce the particulate matter loss during rinsing and on quantifying the particulate matter loss that occurs during incubation in the rumen itself. To quantify particulate matter loss during incubation, loss of small particles during the in situ incubation was studied using undegradable silica with different particle sizes. Particulate matter loss during incubation was limited to particles smaller than ~40 μm with a mean fractional particulate matter loss rate of 0.035 h−1 (first experiment) and 0.073 h−1 (second experiment) and an undegradable fraction of 0.001 and 0.050, respectively. In the second experiment, the fractional particulate matter loss rate after rinsing in a water bath at 50 strokes per minute (s.p.m.) (0.215 h−1) and the undegradable fraction at 20 s.p.m. (0.461) were significantly larger than that upon incubation in the rumen, whereas the fractional particulate matter loss rate (0.140 and 0.087 h−1, respectively) and the undegradable fraction (0.330 and 0.075, respectively) after rinsing at 30 and 40 s.p.m. did not differ with that upon rumen incubation. This new approach was applied to estimate the in situ fractional degradation rate of insoluble organic matter (OM) and insoluble nitrogen (N) in three different wheat yeast concentrates (WYC). These WYC were characterised by a high fraction of small particles and estimating their fractional degradation rate was not possible using the traditional washing machine rinsing method. The new rinsing method increased the mean non-washout fraction of OM and N in these products from 0.113 and 0.084 (washing machine method) to 0.670 and 0.782, respectively. The mean effective degradation (ED) without correction for particulate matter loss of OM and of N was 0.714 and 0.601, respectively, and significant differences were observed between the WYC products. Applying the correction for particulate matter loss reduced the mean ED of OM to 0.676 (30 s.p.m.) and 0.477 (40 s.p.m.), and reduced the mean ED of N to 0.475 (30 s.p.m.) and 0.328 (40 s.p.m.). These marked reductions in fractional degradation rate upon correction for small particulate matter loss emphasised the pronounced effect of correction for undegraded particulate matter loss on the fractional disappearance rates of OM and N in WYC products.

Bio‐inspired packet dropping for ad‐hoc social networks

SummaryAd‐hoc social networks (ASNETs) explore social properties of nodes in communications. The usage of various social applications in a resource‐scarce environment and the dynamic nature of the network create unnecessary congestion that might degrade the quality of service dramatically. Traditional approaches use drop‐tail or random‐early discard techniques to drop data packets from the intermediate node queue. Nonetheless, because of the unavailability of the social properties, these techniques are not suitable for ASNETs. In this paper, we propose a Bio‐inspired packet dropping (BPD) algorithm for ASNETS. BPD imitates the matching procedure of receptors and epitopes in immune systems to detect congestions. The drop probability settings depend on the selection of data packets, which is based on node popularity level. BPD selects the most prioritized node through social properties, which is inspired by the B‐cell stimulation in immune systems. To fairly prioritize data packets, two social properties are used: (1) similarity and (2) closeness centrality between nodes. Extensive simulations are carried out to evaluate and compare BPD to other existing schemes in terms of mean goodput, mean loss rate, throughput, delay, attained bandwidth, and overhead ratio. The results show that the proposed scheme outperforms these existing schemes. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Developing an adaptive radiation therapy strategy for nasopharyngeal carcinoma

Adaptive radiotherapy (ART) has recently been introduced to restore the planned dose distribution by accounting for the anatomic changes during treatment. By quantifying the anatomic changes in nasopharyngeal carcinoma (NPC) patients, this study aimed to establish an ART strategy for NPC cases. A total of 30 NPC patients treated with helical tomotherapy were recruited. In the pretreatment megavoltage CT images, the anatomic changes of the posterolateral wall of nasopharynx (P-NP), neck region and parotid glands were measured and assessed. One-way repeated measure ANOVA was employed to define threshold(s) at any time-point. The presence of a threshold(s) would indicate significant anatomical change(s) such that replanning should be suggested. A pragmatic schedule for ART was established by evaluating the threshold for each parameter. Results showed the P-NP, parotid gland and neck volumes demonstrated significant regressions over time. Respectively, the mean loss rates were 0.99, 1.35, and 0.39 %/day, and the mean volume losses were 35.70, 47.54 and 11.91% (all P < 0.001). The parotid gland shifted medially and superiorly over time by a mean of 0.34 and 0.24 cm, respectively (all P < 0.001). The neck region showed non-rigid posterior displacement, which increased from upper to lower neck. According to the threshold occurrences, three replans at 9th, 19th and 29th fractions were proposed. This ART strategy was able to accommodate the dosimetric consequences due to anatomic deviation over the treatment course. It is clinically feasible and would be recommended for centers where an adaptive planning system was not yet available.

Robot Versus Laparoscopic Nerve-Sparing Radical Hysterectomy for Cervical Cancer

The aim of the study was to compare the initial surgical outcomes and learning curve of nerve-sparing robotic radical hysterectomy (RRH) with nerve-sparing total laparoscopic radical hysterectomy (TLRH) for the treatment of early-stage cervical cancer in the first 50 cases. Between January 2008 and March 2012, 50 consecutive patients underwent nerve-sparing RRH. These patients were compared with a historic cohort of the first 50 consecutive patients who underwent nerve-sparing TLRH. Both groups were similar with respect to patients and tumor characteristics. The mean operating time in the RRH group was significantly longer than that in the TLRH group (230.1 ± 35.8 vs 211.2 ± 46.7 minutes; P = 0.025). The mean blood loss for the robotic group was significantly lower compared with the laparoscopic group (54.9 ± 31.5 vs 201.9 ± 148.4 mL; P < 0.001). There was no significant difference in the mean pelvic lymph nodes between the 2 groups (25.0 ± 9.9 vs 23.1 ± 10.4; P = 0.361). The mean days to normal residual urine were 9.6 ± 6.4 in RRH and 11.0 ± 6.2 in TLRH (P = 0.291). The incidence of intraoperative complication was profoundly lower in RRH compared with that of TLRH (0% vs 8%; P = 0.041). Moreover, no intraoperative transfusion was required in RRH, whereas 4 (8%) were required in TLRH (P = 0.041). In both groups, we found no evidence of a learning effect during the first 50 cases. During the first 50 cases, surgical outcomes and complication rates of nerve-sparing RRH were found to be comparable to those of nerve-sparing TLRH. Moreover, the mean blood loss and intraoperative complication rate in the robotic group were significantly lower than those in the laparoscopic group. Surgical skills for nerve-sparing TLRH easily and safely translated to nerve-sparing RRH in case of experienced laparoscopic surgeon.

Temporal characteristics of pulses produced by the simultaneous coupling of modes in free-running class-C lasers

The behavior of class-C lasers in the simultaneous oscillation state of three longitudinal modes is investigated. The general features of these lasers are described by three coupled variables of the cavity electric field, the atomic population inversion, and the dipole moment of atoms. These variables are related to each other by the usual Maxwell–Bloch equations of motion. We solve these equations to derive the amplification gains of the central and adjacent modes and to determine the contribution amount of these modes in the pulses produced by the mode-locking process. The results indicate that the power of pulses is directly boosted by increasing the laser pumping rate and reducing the mean loss rate of the cavity adjacent modes. Finally, the amplitude and phase of all cavity electric field components are calculated and their consistent with the energy conservation law is illustrated.

Effects of three different types of anaesthesia on perioperative bleeding control in functional endoscopic sinus surgery

The aim of the study was to assess the effect of three different types of anaesthesia on perioperative bleeding control and to analyse the mean arterial blood pressure and heart rate in patients undergoing endoscopic paranasal sinus surgery. Ninety patients (30 women and 60 men, aged 18–85 years) scheduled to undergo functional endoscopic sinus surgery in the years 2008–2010 were identified as candidates for inclusion in the study. Patients were randomly assigned to one of three groups (30 patients each) according to the type of general anaesthesia to be administered. Groups I and II both received inhalation anaesthesia (sevoflurane for sedation) and intravenous anaesthesia (fentanyl in group I, remifentanil in group II). Anaesthesia was delivered solely via intravenous route (TIVA) in group III, with propofol used for sedation and remifentanil for analgesia. Blood pressure and heart rate were monitored during surgery and post-surgically for 4 h. Mean anaesthesia duration in groups I, II and III was 108.7 ± 20.8, 112.6 ± 22.2 and 103.7 ± 17.5 min and the surgery duration was 71.3 ± 16.7, 78.8 ± 24.2 and 66.5 ± 15.5 min, respectively. Mean blood loss during surgery was 365.0 ± 176.2, 340.0 ± 150.5 and 225.0 ± 91.7 ml, with a mean blood loss rate of 5.1 ± 2.4, 4.5 ± 2.2 and 3.4 ± 1.1 ml/min in groups I, II and III, respectively. Technologically advanced control of the drug dose with the TIVA technique allows for better control of perioperative bleeding.

Frequency and spatial distribution of cartilage thickness change in knee osteoarthritis and its relation to clinical and radiographic covariates – data from the osteoarthritis initiative

Estimate the frequency and spatial location of rapid femorotibial cartilage thinning or thickening in knees with, or at risk of, osteoarthritis (OA) and examine their association with clinical and radiographic covariates. Knee cartilage thickness change over 12 months was measured using magnetic resonance imaging in the right knee of 757 Osteoarthritis Initiative (OAI) participants that had radiographic findings of osteophytes or joint space narrowing (JSN). Thickness changes in individual knees were classified as having rapid thinning or thickening or no detectable OA-related change when compared to asymptomatic OAI Control cohort knees. Cartilage thinning, found in 18.5% of subjects, was more frequent in knees with OAI calculated Kellgren-Lawrence grade (cKLG) > 2 (P < 0.001) and with frequent pain (P = 0.047). No link was found between body mass index, sex, and age and cartilage thinning (P > 0.15). The percent of knees with thickening was small (4.4%), but greater in knees with frequent pain (P = 0.02). Rapid thinning was most common in the central (36.4%) and external (32.1%) subregions of the medial weight-bearing femur. Mean cartilage loss in rapidly thinning subregions ranged from 11.2%/y to 24.6%/y. Knees with cKLG > 2, but classified as having no detectable OA-related change had mean cartilage loss rates significantly >0 (0.4%/y-1.3%/y) in 10 subregions. Most observed subregional changes in OA knees were indistinguishable from changes found in an asymptomatic cohort, but a fraction of subregions showed rapid progression. The relative frequency of rapid thinning increases when cKLG > 2, a classification closely associated with JSN and/or frequent knee pain are present.

SOIL LOSS FROM EROSION IN THE NEXT 50 YEARS IN KARST REGIONS OF MAYABEQUE PROVINCE, CUBA

To date, neither the method nor diagnostic indices employed in Cuba to evaluate erosion of Red Ferralitic or Ferrasol Rhodic soil in karstic regions has taken into consideration morphogenesis in such geo-ecosystems or their relationship with erosion, which has led to sequential degradation of the most productive soils in Cuba. We explore the case for considering A + B horizon depth as one of the basic indices for evaluating the severity of erosion. There is no methodology available for estimating the volume of soil lost through karstic absorption forms (dolines). This article forecasts loss of soil cover using a model which estimates losses of 268·52 to 450·52 mm y−1 for future scenarios (periods of 25 and 50 years). A mean loss rate of 1·07 mm y−1 was found in areas cultivated as pastureland during the period from 1986 to 2009, which exceeds the tolerance thresholds proposed by the Universal Soil Loss Equation and the soil formation rates estimated for limestone in Cuba and it is likely there is with a marked tendency for this to increase. These results should be interpreted as a first estimate for setting loss tolerances as there is no similar experience with own data for a more precise definition of the erosion of soil in karstic regions. Copyright © 2012 John Wiley & Sons, Ltd.

Intervertebral focal surgery for the treatment of non-contiguous multifocal spinal tuberculosis.

The purpose of this study was to assess the clinical efficacy of intervertebral focal surgery by complete debridement, deformity correction, graft fusion, and internal fixation for patients with non-contiguous multifocal spinal tuberculosis. A total of 29 cases with non-contiguous multifocal spinal tuberculosis admitted to the hospital from January 2000 to January 2007 were treated by intervertebral focal surgery. There were 63 foci in 29 cases, averaging 2.2 foci per case, and 146 affected vertebral bodies, averaging 2.3 vertebral bodies per focus. Three cases had one normal intervertebral disc between two foci, and the other 26 cases had two or more normal intervertebral discs between two foci. All cases were followed-up for an average of five years. The kyphosis showed a mean correction rate of 67.7% after surgery. A mean loss rate of correction of 8.2% was observed at the final follow-up. The levels of erythrocyte sedimentation rate and C-reactive protein returned to normal in 27 cases on average at 5.8months and bone union could be observed at fivemonths after surgery. Eleven cases with nerve damage recovered to E grade at the final follow-up. Intervertebral focal surgery by complete debridement, deformity correction, graft fusion, and internal fixation for patients with non-contiguous multifocal spinal tuberculosis was feasible and effective.

Laparoscopic, robotic and open method of radical hysterectomy for cervical cancer: A systematic review

BACKGROUND:Over the last two decades, numerous studies have indicated the feasibility of minimally invasive surgery for early cervical cancer without compromising the oncological outcome.OBJECTIVE:Systematic literature review and meta analysis aimed at evaluating the outcome of laparoscopic and robotic radical hysterectomy (LRH and RRH) and comparing the results with abdominal radical hysterectomy (ARH).SEARCH STRATEGY:Medline, PubMed, Embase, Cochrane library and Reference lists were searched for articles published until January 31st 2011, using the terms radical hysterectomy, laparoscopic radical hysterectomy, robotic radical hysterectomy, surgical treatment of cervical cancer and complications of radical hysterectomy.SELECTION CRITERIA:Studies that reported outcome measures of radical hysterectomy by open method, laparoscopic and robotic methods were selected. Data collection and analysis: Two independent reviewers selected studies, abstracted and tabulated the data and pooled estimates were obtained on the surgical and oncological outcomes.RESULTS:Mean sample size, age and body mass index across the three types of RH studies were similar. Mean operation time across the three types of RH studies was comparable. Mean blood loss and transfusion rate are significantly higher in ARH compared to both LRH and RRH. Duration of stay in hospital for RRH was significantly less than the other two methods. The mean number of lymph nodes obtained, nodal metastasis and positive margins across the three types of RH studies were similar. Post operative infectious morbidity was significantly higher among patients who underwent ARH compared to the other two methods and a higher rate of cystotomy in LRH.CONCLUSIONS:Minimally invasive surgery especially robotic radical hysterectomy may be a better and safe option for surgical treatment of cervical cancer. The laparoscopic method is not free from complications. However, experience of surgeon may reduce the complications rate.

Mass dynamics of coarse woody debris in an old-growth deciduous forest of Gwangneung, Korea

We investigated the mass dynamics of coarse woody debris (CWD) in an old-growth deciduous forest dominated by Quercus serrata, Carpinus laxiflora, and C. cordata in a 1 ha permanent plot of the Gwangneung Experiment Forest, Korea, from 2002 through 2010. CWD mass varied from 16.8 to 34.2 Mg ha−1, and the ratio of CWD mass to stand biomass varied from 0.06 to 0.13. The mean CWD mass input and loss rates were 4.81 Mg ha−1 yr−1 and 2.28 Mg ha−1 yr−1, respectively. A large heterogeneity of CWD mass, as represented by the spatial coefficient of variation (127.2%) and annual coefficient of variation (178.5%), might be inherent in the old-growth temperate forest, which consisted of large biomass trees. The decay rate constant, as estimated from the wood density change, was 0.049yr−1. However, the large variation of annual CWD mass input could cause the overestimation of decay rate constant (0.167 yr−1) as calculated from the ratio of CWD mass input to CWD mass. According to the CWD decay class classification, class II (72.8%) comprised the majority of CWD mass. The proportion of CWD mass to total CWD mass was 57.5% for Q. serrata, 25.0% for C. laxiflora, and 10.4% for C. cordata, respectively, and corresponded to the proportion of stem biomass to total stem biomass. These data support the stability of the current status in this old-growth deciduous forest as representing the climax stage. Due to the relatively short-term measurement of CWD mass compared with the whole life span of CWD, additional long-term studies with various approaches are required to enhance the knowledge of CWD mass dynamics in this forest.

Clinical results of posterolateral fusion in treating lumbar low-grade spondylolisthesis

To analyze the clinical outcomes and losses of correction for posterolateral fusion on low-grade lumbar spondylolisthesis. From October 2001 to July 2008, 37 patients with a mean age of 60.1 years (range, 27 - 88 years) with low-grade lumbar spondylolisthesis treated with posterolateral fusion, including 9 males and 28 females, were reviewed retrospectively. The clinical outcomes were evaluated using the visual analogue scale (VAS) and Oswestry disability index (ODI). The fusion status and loss of correction were assessed using plain radiographs and CT. All the 37 patients had got complete follow-up for 14 - 96 months (average 36.4 months); post-operative reduction rate was 76.4%, and 34 patients (91.9%) showed loss of correction with a mean loss rate 5.8% (range, -3.0% - 25.8%). The percentage of slip of pre-operative, post-operative and final follow-up indicated significant difference (P < 0.05)compared with each other; post-operative intervertebral disc height indicated significant difference in comparison with that of pre-operatively and at final follow-up (P < 0.05); lumbar lordosis angle at final follow-up showed significant difference when compared with that of pre-operatively and postoperatively (P < 0.05); VAS and ODI at final follow-up indicated significant difference in contrast to that of pre-operative (P < 0.05). Upon final follow-up, the complications were found in 2 cases who presented degenerative scoliosis at 15 and 17 months after the surgery, in 1 case with cranial adjacent segment retrolisthesis at the 14 months after the surgery, in 1 case with cut-out and breakage of screws at the 24 months after the surgery, and in 1 case with postoperative infection which were cured after debridement. For mid-term follow-up of low-grade lumbar spondylolisthesis, posterolateral fusion shows loss of correction in most cases, but presents good clinical outcome and fusion rate.

2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula

AbstractWe investigate the elevation and mass-balance response of tributary glaciers following the loss of the Larsen A and B ice shelves, Antarctic Peninsula (in 1995 and 2002 respectively). Our study uses MODIS imagery to track ice extent, and ASTER and SPOT5 digital elevation models (DEMs) plus ATM and ICESat laser altimetry to track elevation changes, spanning the period 2001–09. The measured Larsen B tributary glaciers (Hektoria, Green, Evans, Punchbowl, Jorum and Crane) lost up to 160 m in elevation during 2001–06, and thinning continued into 2009. Elevation changes were small for the more southerly Flask and Leppard Glaciers, which are still constrained by a Larsen B ice shelf remnant. In the northern embayment, continued thinning of &gt;3 m a−1 on Drygalski Glacier, 14 years after the Larsen A ice shelf disintegrated, suggests that mass losses for the exposed Larsen B tributaries will continue for years into the future. Grounded ice volume losses exceed 13 km3 for Crane Glacier and 30 km3 for the Hektoria–Green–Evans glaciers. The combined mean loss rate for 2001–06 is at least 11.2 Gt a−1. Our values differ significantly from published mass-budget-based estimates for these embayments, but are a reasonable fraction of GRACE-derived rates for the region (∼40 Gt a−1).

Organic matter losses from temperate ombrotrophic peatlands: an evaluation of the ash residue method

Peatlands act as CO2 sinks that store more soil carbon per unit area than any other ecosystem. Increased aeration and subsequent oxidation following drainage causes peatlands to lose carbon and leads to a relative increase in the concentration of inorganic compounds. To infer carbon losses as a result of drainage, we studied four sites in Central Europe with different drainage states and land-use histories. We used differences in ash content of both catotelm peat and near-surface layers as well as the results of soil carbon inventories. The method yielded reasonable results, at least for two drained sites, where the mean loss rates varied between 0.14 and 0.49 kg C m−2 a−1. Comparison with a pristine bog showed that a relative increase of ash content is not unique to drained sites and that previous land management also affected natural peatlands with concomitant losses similar in magnitude to their drained counterparts. Rehabilitation of a previously drained site dissipated the original ash peak profile. In conclusion, the method is suitable for predicting carbon losses from ombrotrophic bogs under certain conditions but in countries with a long-lasting tradition of anthropogenic interference it is impossible to attribute drainage as the only factor governing relative increases in ash content in ombrotrophic peatlands.

Effect of Bladder Neck Preservation during Endoscopic Extraperitoneal Radical Prostatectomy on Urinary Continence

Objective: The current study investigates the effect of bladder neck (BN) preservation on postoperative continence and positive surgical margins (+SMs). Patients and Methods: 150 patients (group 1) who underwent BN-sparing endoscopic extraperitoneal radical prostatectomy (EERPE) and 90 patients treated with EERPE and BN resection (group 2) were retrospectively evaluated. Results: Both groups were similar for age, prostate-specific antigen and prostate size. There was no significant difference in operative time, mean blood loss or transfusion rate. Mean catheterization time was similar. The overall +SM rates were very similar at 10.7% for group 1 and 10.0% for group 2 (group 1, pT2 = 5.1% and pT3 = 30.3%; group 2, pT2 = 2.9% and pT3 = 33.3%). One of 16 patients in group 1 and 1 of 9 in group 2 had a +SM at BN. Statistically significant differences in continence were observed 24 h after catheter removal and 3 months postoperatively between both groups. Conclusion: BN preservation proved to have an impact on postoperative early continence of patients undergoing EERPE. Continence of patients who underwent BN preservation was improved after catheter removal and at the 3-month follow-up in comparison to those without BN preservation, but +SMs were not affected by the BN-sparing surgery.

Old Lessons Relearned: The Asset Price Dynamics of High-Yield Bonds

This study investigates the asset price dynamics of high-yield bonds. High-yield bonds are debt instruments issued by corporate borrowers with a credit rating below investment grade. The noninvestment grade rating is typically the result of greater reliance on debt in the firm’s capital structure. The study finds that the models used in the contemporary literature to price defaultable claims are not well suited for explaining the price movements of high-yield bonds. The only channel through which exogenous shocks can impact price movements in these models is through mean loss rates, but much of the change in high-yield bond prices seems related to the market price of risk. The study reviews papers from the finance literature that analytically anticipates the role systematic variance plays in explaining the returns on leveraged finance obligations. A multifactor model is specified and rejected in favor of a state-space representation parameterized through use of the Kalman filter. The recursive process tracks the data exceptionally well and allows the hypothesis of a static market price of risk to be tested and rejected. The hypothesis of a purely random market price of risk is also rejected. The paper provides a sound theoretical and empirical foundation for future research.

On the Analysis of CSMA-Based Control Nets With Priorities and Multicast

In contemporary control nets, random access schemes like CSMA are commonly used and are often enhanced by fixed priorities for some message types to guarantee an upper bound for the transmission time of high-priority messages. The introduction of priorities has a significant impact on the overall quality of service, which means that messages with a low priority may have long transmission times or high loss rates if the whole network is not adequately dimensioned. Thus, capacity planning includes as one of the first steps a model-based analysis of the network. This paper presents an approach to analyze the quality of service of CSMA-based control nets. Based on open queueing networks, analytical formulas are derived that allow one to compute performance measures like mean throughputs, loss rates, and response times in an extremely efficient way and with limited information about the system load. Particular emphasis is spent on the analysis of priorities in networks using a variant of the CSMA access scheme which has not been analyzed analytically before. Furthermore, the integration of timeouts and multicast communication into the analysis approach is outlined.