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As big data and artificial intelligence (AI) in spine care, and medicine as a whole, continue to be at the forefront of research, careful consideration to the quality and techniques utilized is necessary. Predictive modeling, data science, and deep analytics have taken center stage. Within that space, AI and machine learning (ML) approaches toward the use of spine imaging have gathered considerable attention in the past decade. Although several benefits of such applications exist, limitations are also present and need to be considered.The following narrative review presents the current status of AI, in particular, ML, with special regard to imaging studies, in the field of spinal research.A multi-database assessment of the literature was conducted up to September 1, 2021, that addressed AI as it related to imaging of the spine. Articles written in English were selected and critically assessed.Overall, the review discussed the limitations, data quality and applications of ML models in the context of spine imaging. In particular, we addressed the data quality and ML algorithms in spine imaging research by describing preliminary results from a widely accessible imaging algorithm that is currently available for spine specialists to reference for information on severity of spine disease and degeneration which ultimately may alter clinical decision-making. In addition, awareness of the current, under-recognized regulation surrounding the execution of ML for spine imaging was raised.Recommendations were provided for conducting high-quality, standardized AI applications for spine imaging.

The field of artificial intelligence is ever growing and the applications of machine learning in spine care are continuously advancing. Given the advent of the intelligence-based spine care model, understanding the evolution of computation as it applies to diagnosis, treatment, and adverse event prediction is of great importance. Therefore, the current review sought to synthesize findings from the literature at the interface of artificial intelligence and spine research.A narrative review was performed based on the literature of three databases (MEDLINE, CINAHL, and Scopus) from January 2015 to March 2021 that examined historical and recent advancements in the understanding of artificial intelligence and machine learning in spine research. Studies were appraised for their role in, or description of, advancements within image recognition and predictive modeling for spinal research. Only English articles that fulfilled inclusion criteria were ultimately incorporated in this review.This review briefly summarizes the history and applications of artificial intelligence and machine learning in spine. Three basic machine learning training paradigms: supervised learning, unsupervised learning, and reinforced learning are also discussed. Artificial intelligence and machine learning have been utilized in almost every facet of spine ranging from localization and segmentation techniques in spinal imaging to pathology specific algorithms which include but not limited to; preoperative risk assessment of postoperative complications, screening algorithms for patients at risk of osteoporosis and clustering analysis to identify subgroups within adolescent idiopathic scoliosis. The future of artificial intelligence and machine learning in spine surgery is also discussed with focusing on novel algorithms, data collection techniques and increased utilization of automated systems.Improvements to modern-day computing and accessibility to various imaging modalities allow for innovative discoveries that may arise, for example, from management. Given the imminent future of AI in spine surgery, it is of great importance that practitioners continue to inform themselves regarding AI, its goals, use, and progression. In the future, it will be critical for the spine specialist to be able to discern the utility of novel AI research, particularly as it continues to pervade facets of everyday spine surgery.

summary Pure stands of Trifolium repens L. N.Z. Huia and Lolium perenne L. S32 and mixtures of various densities and frequencies were treated with sulphuric acd solutions of pH 2.5, 3.5 and 5.6. The species yield was recorded over five sequential harvests. Multifactorial response equations were used to describe the behaviour of the species yield as a function of acidity and the density of both species. Predictions, made through these models, showed that the response of yield of these species to simulated acid rain treatments Varied greatly depending on the planting density, the time of harvesting and on whether the plants were growing in monoculture or in mixture. This suggests that it is not sufficient to consider the effects of experimentally applied acid rain on single individuals or low density stands, since the results obtained will not reflect the response in a close canopy sward.

Fuel is assessed as alternative heat sink for future aircraft applications to avoid excessive drag from conventional cooling systems. Two cooling concepts using fuel as a heat sink are investigated for a hybrid electric aircraft platform with entry into service of year 2035+, 180 PAX and a design range of 1300 nm. The hybrid electric propulsion system produces a maximum heat power of 126.1 kW. Concept 1 uses active hot fuel circulation underneath the wing surfaces for cooling, whereas Concept 2 uses heat exchangers placed inside the existing tanks. Concept 1 is subdivided based on the fuel flow architecture into series and parallel configuration. Thermodynamic modeling is based on semi empirical methods combining effects of internal and external convection, conduction and radiation to an overall heat transfer model. A partial dependence analysis is performed to ensure the model's integrity. The cooling power potential of both concepts is evaluated at five mission points for the reference aircraft. Concept 1 provides sufficient cooling power for all operating points within the operational limits of the fuel temperature except for the Taxi case, in which the required cooling power is 85% fulfilled. The series and parallel sub configurations of Concept 1 are capable of equal cooling powers in all operating points. The parallel option requires less than half the hydraulic power of the series option. The final system needs a pump providing 2.3 kW of hydraulic power. Concept 2 fails to provide the required cooling power at any mission point other than Take-Off due to low fuel fill levels. Concept 1 is compared to a reference cooling system using a ram air cooler on aircraft level. A mass and drag sensitivity assessment shows that Concept 1 performance is in the range of 0.0% to +0.6% in fuel burn compared to the ram air cooling system depending on the mass considerations for Concept 1.

Soil is an important store of carbon (C) and there has been recent concern that accelerated loss of carbon from the soil may be reinforcing climate change. There is therefore a need to both track current trends in soil C storage and to identify how soil can contribute to carbon emission reduction targets. Countryside Survey (CS) is an integrated national monitoring program in which vegetation, topsoil, water and land use measurements are made across Great Britain (GB). The soil component of CS is unique as topsoil C concentrations have been measured at three time points (1978, 1998 and 2007) together with topsoil bulk density (2007 only), vegetation composition (all years), and land use (i.e. Broad Habitat, 1998, 2007). The combined dataset allows estimates of change in topsoil C stock over time and the influence of land use change on topsoil C to be investigated. Results indicate that although there was a small increase (8%) in topsoil C concentration between 1978 and 1998 and small decrease (6.5%) between 1998 and 2007, there was no significant change in GB topsoil C concentration (in g kg−1), density (in t ha−1) or stock (in Tg) between 1978 and 2007. Within individual habitats some consistent trends were observed and by examining plots which had consistent vegetation composition since 1978 we demonstrate that land use change was not responsible for the few significant changes that were found. These results are comparable with the few other estimates of recent topsoil C concentration and stock changes in W. Europe, with the exception of a previous study in England and Wales which reported significant topsoil C losses of up to 50% over a similar period. Possible reasons for the contradictory findings are discussed. An extra 220–730 Tg of C would be stored in topsoil C stocks if all GB soils were optimised at the top 5–25% C densities as recorded for each habitat in 2007.

Strukturelle Komplikationen stellen vergleichsweise seltene Komplikationen infolge akuter Myokardinfarkte dar, die aber mit einer sehr hohen Letalitat einhergehen. Nachdem herzchirurgische Verfahren lange die einzige Therapieoption darstellten, werden nun zunehmend auch interventionelle Verfahren zur Behandlung struktureller Akutkomplikationen eingesetzt. Der Vorteil der Katheterverfahren liegt dabei vor allem in der geringeren Invasivitat in der Behandlung der zumeist hamodynamisch instabilen Patienten, so z. B. in der Therapie der akuten Papillarmuskeldysfunktion oder des Infarkt-VSD. Daruber hinaus haben sich interventionelle Verfahren in der Behandlung der postinfarziellen funktionellen Mitralklappeninsuffizienz und der Volumenreduktion bei Aneurysmen des linken Ventrikels etabliert.

Increasing environmental awareness and expected growth in air traffic over the next decades drive the need for the development of new technologies in the aviation industry. To meet established emission and noise reductions, all-electric aircraft are a promising technology. Yet, current battery technology is far from attaining the specific energy required to design economically viable commercial transport aircraft. To address this problem, much work is undertaken on improving the efficiency of individual components separately. Ongoing research on structural power technology however, focuses on combining load-bearing and electric energy-storage capabilities in a multifunctional material, promising considerable savings in overall aircraft mass. In this paper, a feasibility analysis and a comparative assessment of this technology in two small all-electric reference aircraft is undertaken. The Airbus E-Fan 1.0 and the Bristol Eco-Flyer are evaluated with respect to their mission performance and mass of material eligible for substitution with multifunctional material. Required specific energy and power of multifunctional material for these two-seater aircraft is calculated considering lower mechanical properties of multifunctional material and compared against state-of-the-art capabilities of multifunctional material. Finally, implications on mission performance, possible weight savings and on aircraft design are investigated. The results show that for a constant amount of carried energy, endurance gains of about 31 % are possible. The required minimal specific energy for multifunctional material in aircraft of the considered category is 51.8 W h/kg and the required specific power is 103.3 W/kg for the same mission performance.

Peritoneal carcinomatosis is defined as a metastatic spread of a malignant tumor into the peritoneal cavity. Previously, patients suffering from this kind of malignant peritoneal dissemination were supposed to have a very poor prognosis [1]. However, this situation has improved over the last decade due to the implementation of new systemic and surgical treatment strategies.

Scaled UAV configurations of planned aircraft is well suited for the trial of new aeronautical technologies in flight. These systems offer a significant potential for minimizing costs and complexity. For these reasons project Sagitta has been started with the support of the company Cassidian, namely, to build a scaled demonstrator of a full-scale configuration in order to prove the concept of those technologies. Among others, new technologies with respect to the propulsion system of the demonstrator shall be examined. The demonstrator has a flying wing configuration without vertical stabilizers and is powered by two jet engines. Due to the requirements for a low radar cross section for the full-scale configuration, the propulsion system shall have an adequate integration, leading to a curved propulsion duct, in order to integrate the engines as good as possible in the wing. In order to support lateral stability of the scaled configuration, thrust vectoring functionalities shall be implemented into the nozzle system. These aspects induce difficulties with respect to the integration and challenges with the scaling effects regarding the full-scale configuration. Other important issues of such propulsion integration are the total pressure losses in the inlet and nozzle duct, the thermal loads induced by the engine and the required power for the thrust vectoring concept. For the thrust vectoring system, fluidic concepts have been considered due to their potential for weight, complexity and maintenance effort reduction. Such systems have been mostly tested under laboratory conditions; therefore, a flying demonstrator would suit well for a flight trial of the technology. The presented paper will concentrate on the overall integration aspects of the propulsion system and the initial assessment of promising thrust vectoring solutions.

BACKGROUND: The Surgical Department of the University Hospital Groshadern has been making a systematic record of complications since 2005. With respect to the ongoing problem of under-financing from DRG reimbursements, an analysis of the relationship between surgical cases with severe complications and insufficient reimbursement warranted a detailed analysis. MATERIAL AND METHODS: Out of 16 762 in-house patients during 2005-2007 we assigned 6707 cases into four divisions - hepato-pancreato-biliary, colorectal, minimal invasive and general abdominal surgery - as well as 1469 cases of thoracic surgery, for costs and reimbursement. In all groups patients with mandatory treament of compli-cations were compared to the remaining cases with-out complications. Within these, further subgroups were analysed: patients with a need for artificial ventilation (partition A of the G-DRG system), cases with excessive loss (underfunding above 10 000 Euro) and their intersections. RESULTS: With the exception of minimal invasive surgery, each division featured 10-15 % of serious complications. Losses for these cases ranged from 159 % (thoracic surgery) to 102 % (other abdominal surgery) of the overall loss in each division. Cases with excessive losses, representing 1.5 % of all patients, caused 80 % to 100 % of this deficit. Complicated cases alloted to DRGs for artificial ventilation still represented 50 % of the under-fund-ing. CONCLUSION: Cases with mandatory complication treatment can be discerned as separate economic entities. They are considerably overlapping cases with excessive underfunding, so further analysis might lead to an improved reimbursement pol-icy. In addition, the connection between quality man-agement and economic efficiency is high-lighted.

Wegen der hoheren Inzidenz maligner Tumoren im Alter stellen Malignome in den Industrielandern die zweithaufigste Todesursache ab dem 65. Lebensjahr dar. Die demographische Entwicklung in Deutschland verursacht daher einen erhohten Bedarf an onkologischen Operationen bei alteren Patienten, deren Versorgung kostenintensiver ist. Am Krankengut einer chirurgischen Universitatsklinik soll untersucht werden, ob onkologische Chirurgie bei Patienten uber 80 Jahre durch das geltende DRG-System kostendeckend abgebildet wird. Bei 116 uber 80-jahrigen Patienten mit viszeral- oder thoraxchirurgischen Eingriffen wurden die Kosten und Erlose der Jahre 2005 bis 2007 erfasst. Die errechneten mittleren Ertrage wurden mit den gleichen DRG-Fallen der unter 80 Jahre alten Patienten verglichen. Als mittlerer Ertrag wurden −1493,5 EUR/Fall bei Patienten uber 80 Jahre errechnet. Hierfur ursachlich war das Vorliegen einer Komplikation; der mittlere Ertrag bei fehlender Komplikation war positiv (1297,3 EUR). Die Behandlung von Patienten unter 80 Jahre war durchschnittlich kostendeckend. Onkologische Operationen bei Patienten alter als 80 Jahre wurden durch die geltenden DRGs nicht adaquat abgebildet und verursachen moglicherweise eine Kostendeckungslucke.

Bei maligner Infiltration der Vena cava wird i. Allg. die Indikation fur ein kurativ-resezierendes Verfahren sehr zuruckhaltend gestellt, jedoch konnten ausgewahlte Patienten von einer operativen Sanierung profitieren. Diese Studie zeigt unsere Erfahrungen mit V.-cava-Resektionen bei Tumorinfiltration. Insgesamt wurden 41 Patienten mit Tumoren behandelt, die eine Infiltration der V. cava aufwiesen. Ein alloplastischer Ersatz wurde in 14 Fallen durchgefuhrt. Die ublichen Ergebnisparameter wurden statistisch untersucht. Das mediane Uberleben, ausgenommen der perioperativen Mortalitat von 7% war 28 Monate mit einer 1-, 3- und 5-Jahres-Uberlebensrate von 76%, 33% bzw. 21%. Minorkomplikationen traten bei 13 Patienten auf. Prothesenassoziierte Komplikationen wurden nicht beobachtet. Die Offenheitsrate der Prothesen lag bei 86%. Die Radikalitat der Resektion und das Fehlen kardiopulmonaler Risikofaktoren hatten einen signifikant positiven Einfluss auf das Langzeituberleben. Die Resektion von V.-cava-infiltrierenden Tumoren ist eine mit akzeptierbarem Risiko durchfuhrbare Therapieoption fur ein gut selektioniertes Patientenkollektiv. Besonders Patienten mit Sarkomen, Nieren- oder Nebennierentumoren mit niedrigem Grading und mikroskopisch radikaler Resektion profitieren von einer Operation.

Although advantages of laparoscopic appendectomy (LA) have not yet been proved, there is increasing evidence that LA provides diagnostic and therapeutic advantages as compared to conventional surgery. This article reports the introduction of LA in a university hospital where LA now represents the standard operative procedure in patients with suspected appendicitis.Consecutive patients with appendectomy were prospectively included in the surgical database from 5/1991 to 10/2005. Operating time skin-to-skin in minutes, conversion from laparoscopy to open appendectomy, and complications requiring reoperation as well as surgical expertise were recorded.After initial performance of LA by four experienced specialists in laparoscopic surgery between 1991 and 1994, LA was routinely implemented from 1995 to 2005. Laparoscopic appendectomy was performed in 1,012 patients, and conventional appendectomy in 449 patients, with a LA rate of about 90% in recent years. Intraoperative conversion was deemed necessary in 62 patients (6.2 %) by 40 surgeons among the 103 surgeons who performed LA over 14 years with a mean operative time of 57 +/- 2 min. Between 1995 and 2005 about 25%-30% of LAs were performed as the first LA for the respective surgeon. Laparoscopic appendectomy was associated overall with a reduced length of stay in the hospital compared to open appendectomy (LA: 4.4 +/- 0.1 days versus 6.6 +/- 0.2 in open appendectomy; p0.001).This analysis provides evidence that LA can be introduced in an university hospital with acceptable results despite low operation numbers per surgeon and a liberal teaching policy. The LA procedure, which is associated with a 2%-4% rate of reoperation, may serve as laparoscopy training for young surgeons.

Objective Invasion of the vena cava by malignant tumors is generally considered an absolute contraindication for surgery as a result of high surgical risk. Surgical treatment with resection of the vena cava may be beneficial for selected patients. This study was performed to evaluate our experiences with resection of the vena cava for malignant tumors, with a special focus on secondary tumors involving the inferior caval vein. Methods A total of 35 patients underwent extended resection of malignant tumors invading the vena cava. Prosthetic repair was performed in 13 patients by using a ringed polytetrafluoroethylene graft. Preoperative risk factors, mortality and morbidity, and long-term follow-up and graft patency rates were examined. Results The operative mortality rate was 6%. Minor complications occurred in 12 patients (34%). The graft patency rate was 85%, and there was no graft-related perioperative morbidity. The 1-, 3-, and 5-year survival rates were 76%, 32%, and 21%, respectively, with a median survival of 29 months. Incomplete resection and cardiopulmonary risk have a significant negative effect on survival. Conclusions Radical resection of the vena cava is a feasible procedure in highly selected patients, with low morbidity and mortality and acceptable survival rates, especially in patients with complete resection of the tumor.

Background: In addition to carcino-embryonic antigen (CEA), several oncological biomarkers have been described to be of prognostic relevance in colorectal cancer. Currently, it is still unclear which of these markers are able to provide additive information to established prognostic factors in non-metastatic colorectal cancer. Methods: We investigated whether tumor markers have additive prognostic value to tumor stage in 458 patients with non-metastatic colorectal cancer. Preoperative serum levels of CEA, cancer antigen (CA) 19-9, CA 242, CA 72-4, CYFRA 21-1 and human chorionic gonadotropin (hCGβ) were analyzed. Results: For evaluating disease-free survival (DFS) and overall tumor-related survival (OTS), based on recommendations for adjuvant treatment, patients were divided into the good prognosis group (GPG: colon cancer stage I-II or rectal cancer stage I) and the bad prognosis group (BPG) consisting of the remaining patients with indication for adjuvant treatment. Evaluating tumor markers, linearity was tested. In case of non-linearity a cut-off value was determined. Log (CEA) showed linearity in the GPG and BPG. In the GPG, CEA was the only significant tumor marker, whereas in the BPG, CEA, CA 19-9, CA 242 and CA 72-4 were significant predictors. In multivariate Cox regression analysis, T stage (T3 or T4) and CEA proved independent relevance in the GPG, whereas T4, N2, site, CEA and CA 19-9 were independent predictors in the BPG. Conclusions: CEA and possibly CA 19-9 have additional prognostic value besides tumor stage and, therefore, should be included in the decision for adjuvant treatment.

5 W average output power was achieved with a diode-end-pumped Nd:YVO/sub 4/ regenerative amplifier at a repetition rate of 35 kHz. A commercial 10-psoscillator was used as seed pulse source. Stable TEM/sub 00/ operation was obtained.

Die Diagnose akute Extremitatenischamie kann durch Anamnese, Inspektion und Palpation der Extremitat gestellt werden. Die initiale Therapie besteht in der Bolus-Gabe und anschliesenden kontinuierlichen Behandlung mit unfraktioniertem Heparin. Bei Patienten mit fortgeschrittener Ischamie und vitaler Bedrohung der Extremitat (TASC IIb/III) und wahrscheinlicher arterieller Embolie besteht die Notfalltherapie in der Embolektomie mit dem Fogarty-Katheter als etabliertes Standardverfahren mit anschliesender intraoperativer Angiographie. Patienten mit fehlenden Leistenpulsen und wahrscheinlicher arterieller Thrombose, bekannter pAVK-Symptomatik, vorbestehenden Gefaseingriffen und relevanter Ischamie sollten zunachst durch eine Notfall-Angiographie abgeklart und anschliesend ohne Zeitverzogerung thrombektomiert werden. Nach erneuter intraoperativer Angiographie sind ggf. weitere endovaskulare oder operative Gefaseingriffe erforderlich. Bei akuter Ischamie ohne vitale Bedrohung der Extremitat (TASC IIa) sollte u.E. nach angiographischer Abklarung des Gefasstatus weiterhin die primare Thrombektomie mit intraoperativer Re-Angiographie durchgefuhrt werden mit evtl. gegebener Indikation zum direkt anschliesenden Gefasrekonstruierenden Eingriff oder zur intraoperativen endovaskularen Therapie. Als alternative Therapieoption kann in Einzelfallen die Angiographie-kontrollierte Katheter-gesteuerte lokale Thrombolyse mit dem Ziel der Revaskularisation bzw. der moglichen Demaskierung ursachlicher Gefasstenosen mit anschliesender interventioneller oder sekundar operativer Therapie versucht werden. Im weiteren Verlauf muss die mogliche Entwicklung eines Kompartmentsyndroms beachtet und ggf. eine Fasziotomie vorgenommen werden. Bei Patienten mit schwerster Extremitatenischamie, Muskelnekrosen und begleitendem Organversagen kann im Einzelfall nach einem Thrombektomieversuch die primare Amputation indiziert sein.

Measurements of the performance of a Resistive Gate CCD will be shown and discussed. A short description of structure and layout will be followed by X-ray spectra, linearity, noise, SNR and energy resolution. A charge transfer efficiency of calculated with the classical method of 0.99958±0.00002 was reached. Simulation and layout of a newly designed X-ray Schottky CCD will be presented.

The Simple Mass Balance (SMB) equationis commonly used throughout Europe for thecalculation of acidity critical loads for forestsoils. Different criteria can be set in themodel depending on whether the receptor (e.g. treeroots) is more sensitive to the toxic effects ofaluminium or to unfavourable pH conditions. Thispaper examines the effects on critical loadscalculations of using different criteria andcritical limits, and demonstrates the importanceof selecting the most appropriate and justifiablecriteria for the chosen receptor, since they caneffect the critical loads values obtained. Abrief review of the range of different criteriaand limits used throughout Europe is included. In addition, the gibbsite equilibrium constant,used in the SMB equation to represent therelationship between dissolved aluminium andhydrogen ions in soil solution, is discussed. This relationship is not generally described inthe literature as a criterion in the equation,but this work highlights the effects differentgibbsite values have on critical loadcalculations and the importance of applying themost appropriate value for the soil in therooting zone of the receptor.

Background and aims: During recent years, a discussion about cost-effectiveness and importance of follow-up evaluation after curative resection of large-bowel cancer has developed. It is not known whether the determination of carcinoembryonic antigen (CEA) plays a crucial role in the early detection of recurrent disease. Patients/methods: We conducted an analysis of the prospective follow-up database of 1321 patients after curative resection of colorectal cancer in our institution between 1990 and 1998 to evaluate the role of CEA in the early detection of recurrent disease. Results: Of the 1321 patients included in our study, 306 developed recurrent disease following curative resection (23.2%). These patients with recurrent disease were divided into: Group I. No pre-operative CEA determination/insufficient follow-up (n=47; 15.4%). Group II. No elevation of CEA with primary cancer (n=156; 51.0%): (IIa) elevation with recurrent disease (n=62); (IIb) no elevation at any time point (n=53); and (IIc) role of CEA not completely elucidated (n=41). Thirteen patients of group II underwent curative relapse surgery (8.3%). Group III. Elevated CEA with primary cancer (n=103; 33.7%): (IIIa) no increase with recurrent disease (n=21); (IIIb) increase with other symptoms of recurrent disease (n=45); and (IIIc) increased values as an early symptom of recurrent disease (n=37). Sixteen patients of group III underwent curative relapse surgery (15.5%). In patients after relapse surgery, recurrent disease developed again after a median time of 12 months (mean 17.9±3.8 months). Conclusions: Our findings indicate that 2.8% of all patients (12.1% of patients with recurrent disease) who underwent curative resection of colorectal cancer profit from follow-up CEA determinations. With careful observation of CEA kinetics, 6.2% (n=82) of all patients or 26.8% of patients with recurrent disease could profit from routine follow-up CEA determinations. In 9.5% of patients with recurrent disease, curative resection of relapse was achieved and these patients remained disease free for a median time of 12 months. Regular CEA measurements remain an important part of routine patient care after curative resection of colorectal cancer.

The chemistry of throughfall, from intact canopies and felling debris, and soil waters beneath four tree species, alder (Alnus glutinosa), Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and oak (Quercus petraea), and an unplanted control plot, was monitored before and after felling at a site on humic gley soils in the north of England. The results show clear differences in solute concentrations below the four species both before and after felling. Before felling the concentrations of the mainly atmospherically derived ions (Na+, Mg2+, SO42−, Cl−) were larger in both throughfall and soil waters below the conifers than the hardwoods. There were smaller inter species differences in the concentrations of solutes mainly controlled by within system processes (K+, NO3−, PO4−, DOC); NO3− concentrations were largest below the alder. Following felling, concentrations of the mainly atmospherically derived solutes declined below all four species and the inter-species differences reduced sharply so that in the second year after felling there was little difference between species. Concentrations of the solutes controlled by within system processes mainly increased after felling. The largest increase in K+ concentrations was below the conifers, which had foliage at the time of felling; most of the K was retained in the upper soil except below spruce. Nitrate concentrations declined below alder after felling while increasing below the other species. The largest increase was below spruce and the increased concentrations were seen in the lower horizons below both conifer species, suggesting that there would probably be leakage to ground- or surface waters. The factors leading to the reduction in nitrate concentrations below alder merit further research. PO43− released from the felling debris and litter layer was retained in the upper soil.

Two organometallic complex fragments with 5d6 configurated metal centres of different character, electrophilic [IrIIICp*Cl]+ and π-donating [ReI(CO)3Cl], were used as probes in compounds containing 1,3-dimethyllumazine (DML), 1,3-dimethylalloxazine (DMA), 2-pivaloylpterin (PP) and 6-methyl-2-pivaloylpterin (MPP) as biochemically relevant ligands. Evidence from spectroscopy (NMR, IR, UV–vis) in aprotic solvents points in most cases to the O4 and N5 atoms as chelate donors for metal binding. For [(DMA)IrIIICp*Cl](PF6) this was substantiated by a crystal structure analysis. With PP, however, an iridium(III) compound with pivaloyl-coordinated metal was obtained. Whereas both the IrIII and ReI complexes of the good π acceptor ligand DMA can be reduced reversibly and thus studied by (spectro)electrochemistry (IR, UV–vis, EPR: ligand-centred one-electron reduction), the DML system exhibits such behaviour only for the IrIII species. The complexes of the 2-pivaloylpterins showed only irreversible reduction.

2-Ammoniobutenynyl Ru-complexes trans-[Cl(dppm)2Ru−CC−C(NR2R‘)CH2]+PF6- (3a−g) have been prepared in a one-pot procedure from cis-[RuCl2(dppm)2], excess butadiyne, and various tertairy amines, whereas 4-(dimethylamino)pyridine binds to the unsaturated carbon ligand via the pyridine nitrogen to give 3h. These results may be rationalized by envoking the butatrienylidene complex trans-[Cl(dppm)2RuCCCCH2]+ as the reactive intermediate. Amine complexes cis-[Ru(dppm)2Cl(NR2R‘)]+ are frequently formed as side products and the 4-dimethylaminopyridine derivative cis-[Ru(dppm)2Cl(4-DMAP)]+ was obtained in high yield in the absence of butadiyne but under otherwise identical reaction conditions. Complexes 3 have been characterized by various spectroscopic and electrochemical techniques including cyclic and square wave voltammetry and, in the case of the NEt3 derivative 3a, also by X-ray crystallography. Most complexes 3 undergo a fully reversible one-electron oxidation at half-wave potentials that depend on the amine substituent. This provides evidence for delocalization over the conjugated C3 bridge. EPR spectroscopic investigations of the oxidized forms of the NEt3 and PhCH2NMe2 derived complexes 3a and 3f point to Ru-centered radical dications. The irreversible reduction of complexes 3 occurs in two closely spaced, poorly defined waves and ultimately releases the respective free amine, which itself is reactive toward the Ru(III) oxidation product. Following the oxidation of 3a and 3f by UV/vis and IR spectroelectrochemistry revealed a blue shift of the prominent absorption band and a bleaching of the CC stretch.

Summary To test the hypothesis that canopy thinning might result from phosphorus limitations induced by acidic pollutant deposition, paired stands with ‘thin’ and ‘good’ canopies were compared by examining (1) the phosphorus nutrition of the trees using a root bioassay and (2) availability of phosphorus in surface soil using a resin-extraction procedure. Three pairs of stands of each of Sitka spruce, Scots pine and beech on a range of comparable soils were investigated. A higher level of phosphorus stress in stands with the thinner canopy compared with their corresponding ‘partners’ with the better canopy was demonstrated for eight out of the nine pairs; only the pair of beech stands on gley soils did not comply with this finding. A similar pattern was demonstrated with the soil available phosphorus measurements, namely that surface soils had lower amounts of resin-extractable phosphorus under trees with the thinner canopy compared with their respective ‘partner’ stand with the better canopy; again the beech stands on gley soils did not comply. Analysis of variance indicated that there were significant and complex interactions between tree canopy condition, tree species and soils, in phosphorus stress and surface soil available phosphorus. These results derived from stands distributed over a wide area of northern Britain suggest that there may be a general link between canopy condition and phosphorus stress in trees. However, no link was found between phosphorus stress and estimates of net acidic deposition inputs derived from broad-scale modelling. The critical load for acidic deposition appeared, from these estimates, to be exceeded for all the stands, irrespective of canopy condition. The demonstration of a possible link between tree canopy condition and phosphorus stress suggests that there is a need for a wider investigation, possibly as an integrated part of the UK Tree Health monitoring programme. The hypothesized induction by acidic deposition of phosphorus stress in trees, if true, will require actual monitoring, rather than prediction, of that deposition at each study site.

The pteridine and (iso)alloxazine π systems are the underlying heterocyclic structures of coenzymatic constituents (pterins, lumazines, flavins) of oxidoreductase enzymes. These molecules are potential ligands for metal centers which, in the absence of additional coordination sites, bind predominantly through O(4) and N(5) to form five-membered, redox-active α -iminoketo chelate rings. Recent results from spectroscopic and electrochemical studies and structural data are summarized in this article.

Gallium Arsenide layers grown using low pressure Vapour-Phase Epitaxy (LP-VPE) were studied with CV, Hall-measurements and Photoluminescence. The results have been analysed for the general investigation of the influence of material properties on particle detector performance for X-ray applications. This p-type material exhibits a free carrier concentration of 1.3 × 10 11 cm −3 at room temperature and was compensated by the presence of shallow donors and deep acceptors. Because of this, the detector performance was restricted by the space-charge density of the order of 10 14 cm −3 .

The mobility lifetime product of holes and electrons under low electric field conditions was determined by alpha spectroscopy using SI-GaAs as a photo conductivity detector. The lifetime in high electric field (≥ 10 4 V/cm) of electrons was investigated with Schottky diodes. Both results were analyzed as a function of substrate resistivity and trap concentrations. We identified the ionized arsenic antisite defect (EL2 + ) as the dominant electron trap in the high field region and determined the capture cross-section as being (8.0 ± 0.6) × 10 −14 cm 2 .

Patent foramen ovale (PFO) is a common anatomical variant occurring in 20-25% of the population. In most cases, a PFO remains asymptomatic. However it allows for any venous particle such as thrombus, air or vasoactive substances to bypass the lung and enter the arterial circulation. Accordingly, PFO's have been linked to cryptogenic stroke, migraine and decompression illness. While the number of device closures have been increasing the therapy remains controversial as ‑ until recently ‑ data supporting PFO closure came from non randomized studies only. In this review we will discuss the existing data on PFO closure including results of the three randomized controlled trials comparing device closure with medical therapy in patients with cryptogenic stroke. We will also focus on the implantation technique, the complications and the different devices that are used for this procedure.

Two hydrido ruthenium complexes could be isolated from the reaction between RuCl2(DMSO)4 (DMSO = dimethyl sulfoxide) and the chelating 1,2-bis(dicyclohexylphosphino)ethane (dcpe) and [BPh4]-. These...

This work reports on the fabrication, characterization, and encapsulation of micromachined membrane resonators for ultrasound generation and detection. Based on the encapsulated 1/spl times/1-mm membrane resonators, an ultrasound barrier microsystem for short-distance object detection including the necessary driving circuitry has been developed. Using the ultrasound principle, the barrier microsystem is able to detect, e.g., optically transparent objects. The membrane resonators are fabricated using an industrial silicon technology compatible with bipolar integrated circuit (IC) technology in combination with a postprocessing etching step. Because of the compatibility with IC fabrication technology, the membranes feature electrothermal excitation and piezoresistive detection of transverse vibrations. For the generation of ultrasound, membranes, which exhibit a slight initial buckling due to fabrication-induced compressive stresses, are best suited. At the fundamental resonance frequency f=87 kHz, maximum sound-pressure amplitudes up to 0.25 Pa can be achieved at 50-mm distance. With the piezoresistors arranged in a Wheatstone bridge, a sensitivity for the detection of sound at the resonance S/sub sound/=2 /spl mu/V/mPa (for an applied bias voltage of 5 V) is obtained. To protect the membranes from the environment, they are covered by a metal cap with a periodic grid of holes and a thin, porous membrane. With this encapsulation approach, the generated sound pressure in forward direction is only slightly lowered, while the total beam angle (/spl ap/80/spl deg/) of the generated sound field is distinctly reduced.

Evidence for the functioning of macropores and the presence of preferential flow in forest soils is equivocal. This is partly because many workers use only one diagnostic technique to indicate whether or not macropore flow occurs. In this paper three lines of evidence are used to suggest that preferential flow does not occur in the percolating waters of a coniferous forest soil under the range of hydrological conditions that prevail in the field. To simulate field conditions, realistic rainfall intensities were used in conservative solute transport experiments on four undisturbed soil columns. A method is described in which breakthrough data can be used to calculate the percentage of antecedent water displaced from a soil column during frontal-type breakthrough experiments. Calculations based on this method using the experimental data show that as little as five percent of the antecedent water was immobile. The simple form of the functional advection-dispersion equation, based on a single value for linear velocity and the dispersion coefficient was fitted to two of the breakthrough curves with reasonable accuracy, further suggesting that preferential flow did not occur in the experiments. Finally, soil moisture characteristic curves were determined for replicate soil samples from the forest soil. The operational water contents of the columns during the breakthrough experiments were compared with the soil moisture characteristics and it was found that pores exerting pressure heads greater than -0.5 kPa did not appear to contribute to flow through the columns, again suggesting an absence of preferential flow.

Two methods for the determination of silicon in biological tissue by electrothermal atomic absorption spectrometry using the slurry sampling technique are described. In one of them, a slurry of the tissue and, in the second, a slurry of the ash obtained by separate thermal pre-treatment in an ashing furnace was introduced into the graphite furnace. The second method proved to be superior regarding the elimination of matrix interferences. Optimum sensitivity was obtained by using a mixture of palladium nitrate and magnesium nitrate as modifier. The silicon contents determined were between about 3 and 14 µg g–1 and they were compared with results obtained by other methods and laboratories. The limits of detection of the direct method and the method involving pre-ashing were found to be 0.2 and 0.03 µg g–1, respectively.

In an attempt to model possible metal–pterin or metal–flavin ligand interactions the title compounds have been prepared and their structure, spectroscopy and spectroelectrochemistry (EPR, IR, UV–VIS) compared with results for the corresponding rhodium analogues. The X-ray crystal structure of [(C5Me5)IrCl(DML)](PF6), DML = 1,3-dimethyllumazine, shows O4/N5 chelate coordination of iridium with a shorter bond to the nitrogen centre [2.103(4)vs. 2.186(3)A], a slightly more unsymmetrical situation than that found in the rhodium analogue. Electrochemical studies (cyclic voltammetry, polarography) showed largely reversible one-electron reduction processes to radical species [(C5Me5)IrCl(L)]˙ which allowed us to investigate the EPR, IR and UV–VIS response to the reduction. Although the EPR spectra of the iridium compounds remained unresolved, the low g factors (g < 2) and particular line shapes revealed small but significant contributions from the heavy-metal centre. Long-wavelength absorptions at ca. 600 nm and low-energy shifts of the carbonyl stretching bands confirm the formulation [(C5Me5)IrIIICl(L–1)]˙ for the electronic situation.

Carotid stenting has become a commonly used procedure for the treatment of carotid artery stenosis. Though equipment and techniques have improved tremendously over the recent 3 decades, complications do occur. It is important for carotid operators to be familiar with potential complications and adverse events. In this article complications and adverse events of carotid stenting including those that are related to the vascular access site, vessel spasm, dissection, perforation, thrombotic occlusion and hemodynamic instability and arrhythmias are reviewed. In addition, management strategies are discussed.

Crystals of the semiconductor Cu0.85In1.05Se2 were grown from the melt. The crystals were characterized by scanning electron microscopy as well as transmission electron microscopy. A coexistence of two phases was found in the entire boules which was detected by energy dispersive spectroscopy and by electron diffraction. High resolution electron microscopy showed a direct intergrowth of both phases.

The effects of conventional, bole only harvesting (CH) and whole-tree harvesting (WTH) on major inorganic nutrient concentrations (K, NO3-N, NH4-N, PO4-P and Ca) in soil water are described from Beddgelert forest in North Wales. Monitoring of nutrient leaching losses, and the timing thereof, from brash through the soil and into streams draining the CH areas allowed assessments to be made of the value of brash as a nutrient source for second rotation crops. Most of the K (around 100 kg ha-1) and one-third of the P (10 out of 30 kg ha-1) leached out of the brash lying on the CH plots within one year of felling. A pulse of K passed through the soil profile, but less than half this K reached the streams. In contrast, the P was immobilized in the soil. The lack of brash resulted in the absence of K and P pulses on the WTH plots. On the CH plots, brash was a net sink for inorganic-N for 3 years after felling. However, in both CH and WTH, a pulse of nitrate was observed in the soil and also in streams draining CH areas. The source of this nitrate may have been death of fine tree roots, followed by rapid mineralization and nitrification. Calculation of a nutrient budget for a complete crop rotation indicates that P and Ca losses in harvested material are likely to result in long-term depletion of these elements, and that the effects will be significantly more severe if WTH is practised.