Experimental characterization of superradiance in a single-pass high-gain laser-seeded free-electron laser amplifier

In this Letter we report the first experimental characterization of superradiance in a single-pass high-gain free-electron laser (FEL) seeded by a 150 femtosecond (FWHM) Ti:sapphire laser. The nonlinear energy gain after an exponential gain regime was observed. We also measured the evolution of the longitudinal phase space in both the exponential and superradiant regimes. The output FEL pulse duration was measured to be as short as 81 fs, a roughly 50% reduction compared to the input seed laser. The temporal distribution of the FEL radiation as predicted by a numerical simulation was experimentally verified for the first time.

CDRAP is expressed in adult articular cartilage, but its expression is not significantly regulated in osteoarthritic chondrocytes

OBJECTIVE

In this study we assessed the differential in vivo mRNA expression levels of CDRAP, a potential marker of cartilage degeneration.

METHODS

Conventional and real time PCR in a large series of normal (n = 18) and late stage osteoarthritic (n = 24) cartilage specimens were performed.

RESULTS

Conventional PCR analysis could demonstrate the presence of CDRAP mRNA in normal and osteoarthritic chondrocytes. Real time quantitative PCR confirmed the presence of CDRAP mRNA expression in normal articular chondrocytes in vivo (and in vitro). No significant up-regulation of CDRAP was observed in osteoarthritic chondrocytes in vivo.

CONCLUSION

The presented results confirm expression of CDRAP by normal and osteoarthritic articular chondrocytes, but indicate that increased expression levels by chondrocytes are not the cause of the increased levels of CDRAP in the synovial fluid of patients with osteoarthritis.

Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh

Soil and soil-water As profiles were obtained from 4 rice paddies in Bangladesh during the wet growing season (May-November), when surface water with little arsenic is used for irrigation, or during the dry season (January-May), when groundwater elevated in arsenic is used instead. In the upper 5 cm of paddy soil, accumulation of 13+/-12 mg/kg acid-leachable As (n=11) was observed in soil from 3 sites irrigated with groundwater containing 80-180 microg/L As, whereas only 3+/-2 mg/kg acid-leachable As (n=8) was measured at a control site. Dissolved As concentrations averaged 370+/-340 microg/L (n=7) in the upper 5 cm of the soil at the 3 sites irrigated with groundwater containing 80-180 microg/L As, contrasting with soil water As concentrations of only 18+/-7 microg/L (n=4) over the same depth interval at the control site. Despite the accumulation of As in soil and in soil water attributable to irrigation with groundwater containing elevated As levels, there is no evidence of a proportional transfer to rice grains collected from the same sites. Digestion and analysis of individual grains of boro winter rice from the 2 sites irrigated with groundwater containing 150 and 180 microg/L As yielded concentrations of 0.28+/-0.13 mg/kg (n=12) and 0.44+/-0.25 mg/kg (n=12), respectively. The As content of winter rice from the control site was not significantly different though less variable (0.30+/-0.07; n=12). The observations suggest that exposure of the Bangladesh population to As contained in rice is less of an immediate concern than the continued use of groundwater containing elevated As levels for drinking or cooking, or other potential consequences of As accumulation in soil and soil-water.

Liver transplantation for hepatitis B in the United States

AIM

To evaluate the impact of hepatitis B virus (HBV) on US health care system, we reviewed the Organ Procurement and Transplantation (OPTN, formerly UNOS) HBV database.

METHOD

We reviewed records of liver transplantations (LTx) performed in the United States listed for the diagnoses of HBV between 1993 and mid-October 2004. Both acute as well as chronic cases were included. Coinfection with hepatitis C virus was excluded from study. The specific states selected for review were chosen from those areas that are receiving large numbers of new immigrants from high HBV endemic areas (ie, Texas, Pennsylvania, California, New York, and Florida). One-, 3-, and 5-year patient survival rates for both cadaveric and living related donors were analyzed. Survival rates were obtained from OPTN database as Kaplan-Meyer survival test.

RESULTS

Between 1993 and mid-October 2004, 53,312 LTx had been performed nationwide. Of these, 2314 (4.34%) were performed for the diagnosis of HBV; 1816 cases (78%) were due to chronic HBV infection (45 of them were living donor LTx) and 498 cases (22%) were due to HBV-induced acute liver failure (seven of them were living donor LTx). Three- and 5-year survival rates of chronic HBV-related LTx patients were better than acute HBV-related and overall LTx patients.

CONCLUSION

HBV is generally considered to have a minor health significance by many community gastroenterologists. With growing immigration from overseas, it may eventually have a higher impact on LTx. Therefore, it is crucial to further educate gastroenterologists and primary care physicians caring for this specific group of patients.

Evolution of iron speciation during hydration of C4AF

It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C4AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C4AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C4AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C4AF forms C3AH6 (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C3AH6; iron does not seem to be incorporated in the AFm structure.

XAS study of iron and arsenic speciation during Fe(II) oxidation in the presence of As(III)

The speciation of As and Fe was studied during the oxidation of Fe(II)-As(III) solutions by combining XAS analysis at both the Fe and As K-edges. Fe(II) and As(III) were first hydrolyzed to pH 7 under anoxic conditions; the precipitate was then allowed to oxidize in ambient air for 33 h under vigorous stirring. EXAFS analysis at the As K-edge shows clear evidence of formation of inner-sphere complexes between As(III) and Fe(II), i.e., before any oxidation. Inner-sphere complexes were also observed when Fe became sufficiently oxidized, in the form of edge-sharing and double-corner linkages between AsIIIO3 pyramids and FeIIIO6 octahedra. XAS analyses at the Fe K-edge reveal that the presence of As(III) in the solution limits the polymerization of Fe(II) and the formation of green rust and inhibits the formation of goethite and lepidocrocite. Indeed, As(III) accelerates the Fe(II) oxidation kinetics and leads to the formation of nanosized Fe-As subunits of amorphous aggregates. These observations, rather than a presumed weaker affinity of As(III) for iron oxyhydroxides, might explain why As(III) is more difficult to remove than As(V) by aerating reducing groundwater.

Staff in services for people with intellectual disabilities: the impact of stress on attributions of challenging behaviour

BACKGROUND

There is a lack of a conceptual framework as to how stress and attribution variables interact and influence staff behaviour in response to challenging behaviour. To address this, a model is tested examining the impact of stress on attributions of challenging behaviour within Weiner's model of helping.

METHOD

A total of 107 staff working in community homes for people with intellectual disabilities completed a self-report questionnaire that measured stress, burnout, attributions, emotions, optimism and helping behaviour in response to challenging behaviour.

RESULTS

Partial support was found for the role of attributions and emotions. However, although staff reported high stress levels and moderate burnout, this did not appear to relate to their reporting of thoughts and feelings regarding challenging behaviour predicted by Weiner's helping model. It was not possible to fully test the helping model, as the 'help' variable was not normally distributed.

CONCLUSIONS

There was little evidence to suggest that stress has a primary role in determining staff responses when examined within Weiner's model of helping. Limited support in general was offered for Weiner's helping model. Potential conceptual difficulties and clinical implications are explored and alternative models for future research are discussed.

The impact of total plasma exchange on early allograft dysfunction

INTRODUCTION

Early allograft dysfunction (EAD) is a rare but serious complication encountered among patients undergoing liver transplant surgery. Total plasma exchange (TPE) in EAD has been suggested, but its role is still considered investigational. We retrospectively assessed the efficacy of TPE in EAD and its impact on other parameters of liver function.

MATERIALS AND METHODS

Between 1995 and 2001, 25 orthotopic liver transplant recipients developed EAD, which was defined as early postoperative prothrombin time (PT) >17 seconds, aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) >2500 IU/L, and/or the presence of hepatic encephalopathy, and development of renal failure. Daily TPE was performed using the Cobe Spectra TPE (Gambro) for 4 hours until an adequate clinical response, the patient underwent retransplantation, or the patient died. International normalizing ratio (INR), partial thromboplastin time (PTT), fibrinogen, ALT, AST, gamma-glutanyl transpeptidase (GGT), blood urea nitrogen (BUN), ammonia, and total bilirubin were analyzed before and after TPE. Student t and chi-square tests were used for statistical analysis.

RESULTS

Twenty-five patients with EAD included 13 females, 12 males of mean age 42.3 years (range, 1-63 years). Coagulopathy and hyperbilirubinemia significantly improved with TPE. Nineteen patients (76%) survived and 2 required retransplantation. Mean number of TPE sessions was 4.3.

CONCLUSION

TPE was effective to correct coagulopathy and improve liver function. These results suggest the benefit of potential temporary liver support until recovery or retransplantation, in the absence of sepsis or multi-system organ failure.

Parenting stress in mothers of children with an intellectual disability: the effects of parental cognitions in relation to child characteristics and family support

BACKGROUND

Recent theories of stress and coping in parents of children with intellectual disabilities (ID) emphasize the importance of cognitive appraisals in influencing parents' levels of stress and their adaptations to difficulties presented by the children. This study investigated the relationships between parental cognitions, child characteristics, family support and parenting stress. The aspects of cognitions studied were: parenting self-esteem (including efficacy and satisfaction) and parental locus of control.

METHODS

The group studied consisted of 46 mothers of children with ID. The Vineland Adaptive Behavior Scales and Maladaptive Behavior Domain were administered by interview. Mothers also completed four questionnaires: the Family Support Scale, the Parenting Sense of Competence Scale, a shortened form of the Parental Locus of Control Scale and the Parenting Stress Index (Short Form).

RESULTS

Data were analysed using Pearson's correlation coefficients, partial correlations and a regression analysis. The results indicated that most of the variance in parenting stress was explained by parental locus of control, parenting satisfaction and child behaviour difficulties. Whilst there was also a strong correlation between family support and parenting stress, this was mediated by parental locus of control.

CONCLUSIONS

The results demonstrate the potential importance of parental cognitions in influencing parental stress levels. It is argued that these results have implications for clinical interventions for promoting parents' coping strategies in managing children with ID and behavioural difficulties.

Total mesorectal excision with the water-jet-dissection. Technique and results

BACKGROUND

The introduction of total mesorectal excision (TME), in particular, has resulted in a dramatic decrease in postoperative functional disorders. Strict adherence to the dissection planes described above, is the prerequisite for good oncological and functional outcome. To facilitate dissection, we have introduced the high-pressure water jet dissector into our surgical routine for the treatment of rectal cancer. Below, we describe the technique of total mesorectal excision we employ in our department and present our perioperative surgical results.

METHODS

We performed total mesorectal excision for rectal cancer on 49 patients, comprising 32 males and 17 females aged between 34 and 88 years. 38 patients underwent low anterior resection of the rectum and 11 patients abdominoperineal resection.

RESULTS

The mean operating time was 282 min, mean intraoperative administration of red cell concentrates was 0.55 units. The mean postoperative stay in the ICU was 1.92 days. Anastomotic leakage occurred in 6.1%, wound healing disturbances in 12.2%, urinary tract infection in 12.2% intra-abdominal infection in 4.1% and faecal fistula in 4.1%. Urinary tract infections occurred in 12.2%. Postoperative temporary neurogenic voiding disturbances occurred in 14.3%. Persistent neurogenic bladder dysfunction after three months could be observed in 6.1%.

CONCLUSIONS

The perioperative results are comparable to those of centres of excellence in the international literature. The Hydro-Jet dissector significantly facilitated TME. The particular feature of this technical aid is that it permits the rapid early development of the embryological plane between the pelvic nerves and the mesorectal fascia, without doing damage to either of them. This leads to optimal radicality and 1 maximum preservation of the autonomic nerves. Before a definitive pronouncement on voiding disturbances can be made, however, we consider it necessary to carry out a prospective randomised study with preoperative and postoperative urodynamic investigations.

Results of laparoscopic treatment of rectal cancer: analysis of 520 patients

BACKGROUND

To evaluate short- and long-term outcomes of laparoscopic resection of rectal carcinoma in curative intent.

METHODS

Within a subgroup analysis of a multicentre study, initiated by the "Laparoscopic Colorectal Surgery Study Group (LCSSG)", 520 patients with rectal cancer were included in a prospective, clinical observational study.

RESULTS

One hundred and ninety patients underwent an abdominoperineal resection (APR) and 330 patients an anterior resection (AR) of the rectum. The demographic parameters, intraoperative complication rates, morbidity and mortality rates were comparable in both groups. In patients undergoing AR a trend towards limited oncologic radicality, and a significant increase in the anastomotic leak rate related to the distance of the tumour from the anal verge were observed. Calculated survival data revealed stage-related survival rates for UICC stages I, II and III of 82.0%, 68.8% and 63.3%, respectively.

CONCLUSIONS

While APR is highly suited to the laparoscopic approach, laparoscopic AR cannot at present be generally recommended.

Effect of thermal manikin surface temperature on the performance of personal cooling systems

Thermal manikin experiments were carried out to investigate the effect of manikin surface temperature on the performance of a personal cooling system (PCS), more specifically, a liquid circulating garment (LCG). Three manikin temperatures were tested using a dry thermal manikin torso: 38, 34, and 30 degrees C. Mean environmental temperature during experiments was 23.5+/-1 degrees C. Results show that more heat was extracted from the thermal manikin by the PCS as the manikin surface temperature was increased. This is due to the larger difference in temperature between the manikin and the chilled fluid flowing in the PCS when the manikin temperature is high. Finally, it was demonstrated that if insulating garments that reduce heat losses to the environment were worn over the PCS, the PCS efficiency increased.

Complications in laparoscopic colorectal surgery: results of a multicentre trial

BACKGROUND

We present a prospective observational multicentre study of 4834 consecutive cases undergoing laparoscopic colorectal procedures.

METHODS

The study was initiated on 1 August 1995, with centres from Germany, Austria and Switzerland participating. All patients undergoing laparoscopic colorectal surgery were included, and no selection criteria were applied.

RESULTS

Between August 1995 and April 2004, the participating centres treated 4834 patients. Three thousand, one hundred and sixty-six operations were performed for benign indications, and 1668 for cancer, with most operations being done for diverticulitis (2019, 41.8%). The conversion rate was 5.6%, and the overall morbidity was 20.1%. Intra-operative complications occurred in 5.9%, postoperative complications in 14.0%, and the overall anastomotic leak rate was 3.1% (colon 2.6%, rectum 11.9%). The 30-day mortality rate was 1.3%.

CONCLUSIONS

It has been our experience that laparoscopic surgery for colorectal disease is safe. Morbidity and mortality are comparable to those of conventional colorectal surgery.

Aging theories of primary osteoarthritis: from epidemiology to molecular biology

Osteoarthritis is the most common disabling condition of humans in the western world. It has been known for a very long time that aging is the most prominent risk factor for the initiation and progression of the disease, but the explanations for this phenomenon have changed over time. The most longstanding theory is that osteoarthritis develops because of continuous mechanical wear and tear. However, osteoarthritis can also be the result of time/age-related modifications to cartilage matrix components. One of the simplest biological explanations for the initiation and progression of osteoarthritic cartilage degeneration is a mere loss of viable cells, due to apoptosis or other mechanisms. Overall, the most likely scenario is that the cells and the matrix of articular cartilage get older over time, and eventually the tissue enters a senescence-like state that makes it more prone to enter the osteoarthritic degeneration pathway. Thus, patients with osteoarthritis might progress more quickly to the senescence phenotype compared to others. Moreover, stressful conditions associated with the osteoarthritic disease process might further promote chondrocyte senescence. Primary osteoarthritis in this model would be a "premature" degeneration of the joint due to a premature chondrocyte senescence. By analogy to neurodegenerative disorders, one could refer to osteoarthritis as the "M. Alzheimer" of articular cartilage. One of the most important implications of this hypothesis is that it points to issues of cellular degeneration as the basis for understanding the initiation and progression of osteoarthritis. Equally important, it emphasizes that whatever treatment we envisage for osteoarthritis, we must take into account that we are dealing with aged/(pre)senescent cells that no longer have the ability of their juvenile counterparts to counteract the many mechanical, inflammatory, and/or other assaults to the tissue.

Characterization of the concentration gradient of prostaglandin H synthase 2 mRNA throughout the pregnant baboon uterus

The present study was designed to determine the effect of the spatial gradient from the cervix to the uterine fundus on the control of local prostaglandin H synthase (PGHS) 2 mRNA expression. We performed total cesarean hysterectomies during the last trimester in 12 pregnant baboons, 7 not in labor and 5 in labor, and examined PGHS2 mRNA expression throughout the uterus. PGHS2 mRNA abundance was quantified by in situ hybridization and northern blot analysis in the uterine fundus, lower uterine segment and the different segments of the cervix. Quantitative northern blot and in situ analysis demonstrated a gradient of PGHS2 mRNA expression, with the highest levels at the level of the lower portion of the cervix and decreased expression through the mid- and upper portion of the cervix and lower uterine segment; the lowest levels of expression were seen in the uterine fundus. Moreover, cellular localization of PGHS2 mRNA and protein demonstrated high levels of expression in the cervical glandular epithelial cells with only occasional staining of smooth muscle cells in pregnant baboons. Decreased PGHS2 mRNA concentration gradient from the cervical external os to the fundus suggests that prostaglandin (PG) production in the uterus and cervix strongly depends on anatomical relations. This increased local PG production activity may be critical to pregnancy-associated lower uterine segment elongation, cervical softening and effacement in primate labor. These data provide a compelling biological basis for the use of PGHS2 inhibitors in the prophylaxis of preterm birth and cervical incompetence.