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We consider $f(R)$ gravity and Born-Infeld-Einstein (BIE) gravity in formulations where the metric and connection are treated independently and integrate out the metric to find the corresponding models solely in terms of the connection, the archetypical treatment being that of Eddington-Schr\"odinger (ES) duality between cosmological Einstein and Eddington theories. For dimensions $D\ne2$, we find that this requires $f(R)$ to have a specific form which makes the model Weyl invariant, and that its Eddington reduction is then equivalent to that of BIE with certain parameters. For $D=2$ dimensions, where ES duality is not applicable, we find that both models are Weyl invariant and equivalent to a first order formulation of the bosonic string. We also discuss the form of the boundary terms needed for the variational principle to be well defined on manifolds with non-null boundaries. This requires a modification of the Gibbons-Hawking-York (GHY) boundary term for gravity. This modification also means that the dualities between metric and connection formulations are consistent and include the boundary terms., Comment: 15 pages, one figure; Ver. 2: 16 pages, one figure, various clarifying remarks added, accepted for publication in CQG

Background The population growth rate is an important characteristic of any cell culture. During sustained experiments, the growth rate may vary due to competition or adaptation. For instance, in presence of a toxin or a drug, an increasing growth rate indicates that the cells adapt and become resistant. Consequently, time-dependent growth rates are fundamental to follow on the adaptation of cells to a changing evolutionary landscape. However, as there are no tools to calculate the time-dependent growth rate directly by cell counting, it is common to use only end point measurements of growth rather than tracking the growth rate continuously. Results We present a computer program for inferring the growth rate over time in suspension cells using nothing but cell counts, which can be measured non-destructively. The program was tested on simulated and experimental data. Changes were observed in the initial and absolute growth rates, betraying resistance and adaptation. Conclusions For experiments where adaptation is expected to occur over a longer time, our method provides a means of tracking growth rates using data that is normally collected anyhow for monitoring purposes. The program and its documentation are freely available at https://github.com/Sandalmoth/ratrack under the permissive zlib license.

Targeted therapies for chronic myeloid leukaemia (CML) are effective, but rarely curative. Patients typically require treatment indefinitely, which gives ample time for drug resistance to evolve. Drug resistance issues are one of the main causes of death owing to CML, thus any means of preventing resistance are of importance. Drug rotations, wherein treatment is switched periodically between different drugs are one such option, and have been theorized to delay the onset of resistance. In vitro testing of drug rotation therapy is a first step towards applying it in animal or human trials. We developed a method for testing drug rotation protocols in CML cell lines based around culturing cells with a moderate amount of inhibitors interspersed with washing procedures and drug swaps. Drug rotations of imatinib and ponatinib were evaluated in a CML specific cell line, KCL-22. The growth of KCL-22 cells was initially reduced by a drug rotation, but the cells eventually adapted to the protocol. Our results show that ponatinib in a drug rotation temporarily sensitizes the cells to imatinib, but the effect is short-lived and is eventually lost after a few treatment cycles. Possible explanations for this observation are discussed. Is included in the dissertation as a manuscript titled: Rotating between ponatinib and imatinib temporarily increases the efficacy of imatinib in a cell line model

We discuss conserved currents constructed from the Cotton tensor and (conformal) Killing-Yano tensors (KYTs). We consider the corresponding charges generally and then exemplify with the four-dimensional Pleba\'nski-Demia\'nski metric where they are proportional to the sum of the squares of the electric and the magnetic charges. As part of the derivation, we also find the two conformal Killing-Yano tensors of the Pleba\'nski-Demia\'nski metric in the recently introduced coordinates of Podolsky and Vratny. The construction of asymptotic charges for the Cotton current is elucidated and compared to the three-dimensional construction in Topologically Massive Gravity. For the three-dimensional case, we also give a conformal superspace multiplet that contains the Cotton current in the bosonic sector. In a mathematical section, we derive potentials for the currents, find identities for conformal KYTs and for KYTs in torsionful backgrounds., Comment: 20 pages; ver. 2: to appear in JHEP

We construct invariants for bosonic and spinning tensionless (null) strings in backgrounds that carry Killing tensors or Killing-Yano tensors of mixed type. This is facilitated by the close relation of these strings to point particles. We apply the construction to the Minkowski and to the Kerr-Newman backgrounds., Comment: 16 pages

Background Acute myeloid leukaemia (AML) is an aggressive blood cancer. In approximately 30% of the cases, driver mutations in the FLT3 gene are identified. FLT3 inhibitors are used in treatment of such patients together with cytotoxic drugs or (in refractory AML) as single agents. Unfortunately, resistance to FLT3 inhibitors limits their efficacy. Resistance is often due to secondary mutations in the gene encoding the molecular target. The gatekeeper mutation F691L confers resistance to specific FLT3 inhibitors such as quizartinib, but pexidartinib is much less resistance to this mutation. Pexidartinib alone is however sensitive to many other resistance mutations. In chronic myeloid leukaemia (CML), it has been suggested that rotation between drugs with a different landscape of resistance mutations might postpone the emergence of resistance. Methods We studied the effect of quizartinib and pexidartinib in AML cell lines that express FLT3 (MOLM-14 and MV4-11). Using a rotation protocol, we further examined whether the emergence of resistance could be postponed. Computational modelling was used to analyse the onset of resistance and suggest which mutations are most likely to occur in a quantitative fashion. Results The cells were sensitive to both inhibitors but quickly developed resistance that could be inherited, suggesting a genetic origin. Rotation protocols were not useful to postpone the emergence of resistance, which implies that such protocols, or changing from pexidartinib to quizartinib (or vice-versa) should not be used in patients. The computational modelling led to similar conclusions and suggested that F691L is the most common mutation to occur with quizartinib, and also when both drugs are used in rotation. Conclusions AML patients are not likely to benefit from a quizartinib/pexidartinib rotation protocol. A combination of tyrosine kinase inhibitors (with different molecular targets) might be more useful in the future. Development of specific FLT3 inhibitors that are less sensitive to resistance mutations might also lead to a better outcome.

Background: The aim of this paper is to present the development of the Feel4Diabetes Healthy Diet Score and to evaluate its clinical validity. Methods: Study population consisted of 3268 adults (63% women) from high diabetes risk families living in 6 European countries. Participants filled in questionnaires at baseline and after 1 year, reflecting the dietary goals of the Feel4Diabetes intervention. Based on these questions the Healthy Diet Score was constructed, consisting of the following components: breakfast, vegetables, fruit and berries, sugary drinks, whole-grain cereals, nuts and seeds, low-fat dairy products, oils and fats, red meat, sweet snacks, salty snacks, and family meals. Maximum score for each component was set based on its estimated relative importance regarding T2DM risk, higher score indicating better quality of diet. Clinical measurements included height, weight, waist circumference, heart rate, blood pressure, and fasting blood sampling, with analyses of glucose, total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides. Analysis of (co) variance was used to compare the Healthy Diet Score and its components between countries and sexes using baseline data, and to test differences in clinical characteristics between score categories, adjusted for age, sex and country. Pearson's correlations were used to study the association between changes from baseline to year 1 in the Healthy Diet Score and clinical markers. To estimate reproducibility, Pearson's correlations were studied between baseline and 1 year score, within the control group only. Results: The mean total score was 52.8 ± 12.8 among women and 46.6 ± 12.8 among men (p < 0.001). The total score and its components differed between countries. The change in the Healthy Diet Score was significantly correlated with changes in BMI, waist circumference, and total and LDL cholesterol. The Healthy Diet Score as well as its components at baseline were significantly correlated with the values at year 1, in the control group participants. Conclusion: The Feel4Diabetes Healthy Diet Score is a reproducible method to capture the dietary information collected with the Feel4Diabetes questionnaire and measure the level of and changes in the adherence to the dietary goals of the intervention. It gives a simple parameter that associates with clinical risk factors in a meaningful manner. Trial registration: Clinicaltrials.gov NCT02393872. Registered March 20, 2015. © 2020 The Author(s).

Background: The implementation of population screening and early prevention strategies targeting individuals at high-risk for type 2 diabetes (T2D) seems to be a public health priority. The current work aimed to describe the screening procedure applied in the Feel4Diabetes-study and examine its effectiveness in identifying individuals and families at high risk, primarily for T2D and secondarily for hypertension, among vulnerable populations in low to middle-income countries (LMICs) and high-income countries (HICs) across Europe. Methods: A two-stage screening procedure, using primary schools as the entry-point to the community, was applied in low socioeconomic status (SES) regions in LMICs (Bulgaria-Hungary), HICs (Belgium-Finland) and HICs under austerity measures (Greece-Spain). During the first-stage screening via the school-setting, a total of 20,501 parents (mothers and/or fathers) of schoolchildren from 11,396 families completed the Finnish Diabetes Risk Score (FINDRISC) questionnaire, while their children underwent anthropometric measurements in the school setting. Parents from the identified "high-risk families" (n = 4484) were invited to participate in the second-stage screening, including the measurement of fasting plasma glucose (FPG) and blood pressure (BP). In total, 3153 parents participated in the second-stage screening (mean age 41.1 ± 5.6 years, 65.8% females). Results: Among parents who attended the second-stage screening, the prevalence of prediabetes (as defined by impaired fasting glucose; FPG 100-125 mg/dl) and T2D (FPG > 126 mg/dl) was 23.2 and 3.0% respectively, and it was found to be higher in the higher FINDRISC categories. The percentage of undiagnosed T2D among the participants identified with T2D was 53.5%. The prevalence of high normal BP (systolic BP 130-139 mmHg and/or diastolic BP 85-89 mmHg) and hypertension (systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg) was 14 and 18.6% respectively, which was also higher in the higher FINDRISC categories. The percentage of cases not receiving antihypertensive treatment among the participants identified with hypertension was 80.3%. Conclusion: The findings of the current study indicate that the two-stage school and community-based screening procedure followed, effectively identified high-risk individuals and families in vulnerable populations across Europe. This approach could be potentially scalable and sustainable and support initiatives for the early prevention of T2D and hypertension. Trial registration: The Feel4Diabetes-intervention is registered at http://clinicaltrials.gov/(NCT02393872; date of trial registration: March 20, 2015). © 2020 The Author(s).

Additional file 1: Figure S1. Cell count timelines collected from K562 cells.

Background: Although there are many interventions targeting childhood obesity prevention, only few have demonstrated positive results. The current review aimed to gather and evaluate available school-based intervention studies with family involvement targeting dietary, physical activity and sedentary behaviors among primary schoolchildren and their families, in order to identify the most effective strategies. Methods: Studies published between 2000 and January 2015 were retrieved from scientific electronic databases and grey literature. The databases used included MEDLINE/PubMed, Web-of-Science, CINAHL and Scopus. Included studies had to be experimental controlled studies and had duration over 1 school year, had family involvement, combined PA and dietary behaviors and were implemented in school setting. A complementary search was executed to update the review to cover the period from February 2015 to January 2019. Results: From the studies examined (n = 425), 27 intervention programs (33 publications) fulfilled the inclusion criteria. Among these, 15 presented significant effect on weight status and/ or overweight/ obesity or clinical indices, 3 presented significant effect on most energy balance-related behaviors (EBRBs) while 9 presented significant effect on some/few EBRBs or determinants. Strategies implemented in effective interventions were: teachers acting as role-models and being actively involved in the delivery of the intervention, school policies supporting the availability of healthy food and beverage choices and limiting unhealthy snacks, changes in the schoolyard, in the recess rules and in the physical education classes to increase physical activity, and involving parents in the intervention via assignments, meetings, informative material and encouraging them to improve the home environment. Use of incentives for children, social marketing techniques, collaboration with local stakeholders were found to increase effectiveness. Programs that focused only on educational sessions and material for parents, without promoting relevant environmental and policy changes, were found to be less effective. Cultural adaptations have been suggested to increase the intervention's acceptance in specific or vulnerable population groups. Conclusions: Several effective strategies were identified in the reviewed programs. Outcomes of the current review were taken into account in developing the Feel4Diabetes-intervention and summed up as recommendations in the current work in order to facilitate other researchers designing similar childhood obesity prevention initiatives. © 2020 The Author(s).

Additional file 1 Figure S1–S8 depicting simulation results under a wider range of circumstances, dose response curves and derivations of mathematical formulae.

Background Chronic myeloid leukaemia is in principle a treatable malignancy but drug resistance is lowering survival. Recent drug discoveries have opened up new options for drug combinations, which is a concept used in other areas for preventing drug resistance. Two of these are (I) Axitinib, which inhibits the T315I mutation of BCR-ABL1, a main source of drug resistance, and (II) Asciminib, which has been developed as an allosteric BCR-ABL1 inhibitor, targeting an entirely different binding site, and as such does not compete for binding with other drugs. These drugs offer new treatment options. Methods We measured the proliferation of KCL-22 cells exposed to imatinib–dasatinib, imatinib–asciminib and dasatinib–asciminib combinations and calculated combination index graphs for each case. Moreover, using the median–effect equation we calculated how much axitinib can reduce the growth advantage of T315I mutant clones in combination with available drugs. In addition, we calculated how much the total drug burden could be reduced by combinations using asciminib and other drugs, and evaluated which mutations such combinations might be sensitive to. Results Asciminib had synergistic interactions with imatinib or dasatinib in KCL-22 cells at high degrees of inhibition. Interestingly, some antagonism between asciminib and the other drugs was present at lower degrees on inhibition. Simulations revealed that asciminib may allow for dose reductions, and its complementary resistance profile could reduce the risk of mutation based resistance. Axitinib, however, had only a minor effect on T315I growth advantage. Conclusions Given how asciminib combinations were synergistic in vitro, our modelling suggests that drug combinations involving asciminib should allow for lower total drug doses, and may result in a reduced spectrum of observed resistance mutations. On the other hand, a combination involving axitinib was not shown to be useful in countering drug resistance.

During the Comstock mining era of the late 1800s, forested lands in the North American Great Basin were used for charcoal production to fuel mining smelters and related industries. Archaeological studies within or near mining districts include assessments of charcoal-production sites when such remnant features are present. Minimal historical documentation exists for individual production sites, and so the science of dendrochronology (tree-ring dating) is used to provide calendar dates and other information on the nature of historical activity within forests and woodlands. A synthesis of the dendrochronological approach to historical charcoal-production investigation is presented in the context of four recent studies, including a comprehensive strategy, new processing techniques, and unique results. This approach provides charcoal-production archaeologists with precise temporal and spatial data that are applied to questions such as patterns and timing of deforestation, or differences in technology and practices among immigrant laborers.

The first worldwide interlaboratory assesment on persistent organic pollutants (POPs) under the Stockholm Convention was organized in the Asian/Pacific, Latin American and African regions during 2009-11.A relatively large number of laboratories reported data for the PCDDs/PCDFs and dioxin-like PCBs, especially in the Asian region. Within the Asian region, several participants used high-resolution GC/high-resolution MS systems optimized for dioxin analysis. The availibility of High-resolution mass spectrometer instrumentation is limited in the Latin America and African regions, although recently several new laboratories for dioxins have started in the Latin American region. © 2012.

Proton-irradiated epitaxial pad diodes of 75, 100 and 150 μ m thickness and different oxygen concentrations were studied as an option to withstand the extreme radiation environment in the innermost tracking region of the future Super-LHC. With a new TCT setup using red laser light, time-resolved current signals could be measured in 150 μ m thin diodes. Thus the charge correction method (CCM) could be used to extract the effective trapping times. Similar results compared to previously investigated materials were obtained if the standard model of trapping is assumed, which is based on a constant trapping time at each fluence and neglects detrapping and charge multiplication. Charge collection efficiency (CCE) measured with 5.8 MeV α -particles showed an increase for decreasing thickness, but no dependence on impurity concentration was seen. CCE simulations based on the effective trapping time constants determined with the CCM resulted in systematically lower values than the measurements. This is the case for the CCE of both α -particles , red and infrared laser light. To account for this, possible modifications of the trapping model including voltage- or field-dependent trapping times will be discussed. Moreover, at high fluences and voltages anomalously high CCE > 1 was observed, which indicates charge multiplication effects.

Charge multiplication (CM) in p$^+$n epitaxial silicon pad diodes of 75, 100 and 150 $\upmu$m thickness at high voltages after proton irradiation with 1 MeV neutron equivalent fluences in the order of $10^{16}$ cm$^{-2}$ was studied as an option to overcome the strong trapping of charge carriers in the innermost tracking region of future Super-LHC detectors. Charge collection efficiency (CCE) measurements using the Transient Current Technique (TCT) with radiation of different penetration (670, 830, 1060 nm laser light and $\alpha$-particles with optional absorbers) were used to locate the CM region close to the p$^+$-implantation. The dependence of CM on material, thickness of the epitaxial layer, annealing and temperature was studied. The collected charge in the CM regime was found to be proportional to the deposited charge, uniform over the diode area and stable over a period of several days. Randomly occurring micro discharges at high voltages turned out to be the largest challenge for operation of the diodes in the CM regime. Although at high voltages an increase of the TCT baseline noise was observed, the signal-to-noise ratio was found to improve due to CM for laser light. Possible effects on the charge spectra measured with laser light due to statistical fluctuations in the CM process were not observed. In contrast, the relative width of the spectra increased in the case of $\alpha$-particles, probably due to varying charge deposited in the CM region., Comment: 11 pages, accepted by NIMA

N-type epitaxial layers of 72 μm thickness and a resistivity of 150 Ω cm have been grown on highly Sb-doped Cz-substrates at ITME (Warsaw). The diode processing was performed at CiS-Erfurt. For comparison a batch of 280 μm thick n-type MCz wafers with a resistivity of >600 Ω cm from Okmetic (Finland) was added to the process run. Depth profiles of the oxygen and carbon concentration were measured via the SIMS-method on as grown epi-layers and after different device-process steps at CiS including an oxygen enrichment at 1100 °C for 24 h. For the MCz material the profiles were measured on untreated samples and after the full device process. Irradiation runs were performed with neutrons at the TRIGA reactor of Ljubljana up to a fluence value of 1016 cm−2. The development of the macroscopic device parameters (effective doping concentration and charge collection for α-particles) as function of fluence is presented for the standard and oxygenated epi-devices and compared with the MCz-diodes. The results are discussed in the frame of defect studies resulting from TSC-measurements.

n-Type epitaxial silicon layers of different thickness and resistivity, grown on highly Sb doped CZ-substrate by ITME (Warsaw), and n-type MCz silicon supplied by Okmetic (Finland) were used for the processing of planar diodes at CiS (Erfurt). For the epi-diodes a standard as well as a diffusion oxygenation process was employed. Irradiations had been performed with 26 MeV protons at the cyclotron of the Karlsruhe University and with neutrons at the TRIGA reactor of the Ljubljana University. Microscopic investigations using the DLTS method were done. The correlation of the IO 2 i -defect and the oxygen concentration was studied by a depth-profile measurement. The annealing behavior of the IO 2 i -defect at different temperatures was investigated and the activation energy extracted.

The objective of this chapter is to let a representative cross-section of practitioners, drawn from several regions of the world, reflect on their experiences through short illustrations of the approaches they have adopted to address a PUB problem. The chosen case studies cover the full range of runoff predictions in ungauged basins, using a wide range of methods, in places across broad climatic and geographic gradients. We then undertook a limited assessment of PUB practice seen in the case studies from two perspectives: (i) what lessons can be learned from the experiences of the case studies towards strengthening the outcomes of the synthesis?, and (ii) how can the outcomes of the synthesis help advance the practice of PUB globally?

Diodes processed on n-type epitaxial silicon with a thickness of 25, 50 and 75 μm had been irradiated with reactor neutrons and high-energy protons (24 GeV/ c ) up to integrated fluences of Φ eq =10 16 cm −2 . Systematic experiments on radiation-induced damage effects revealed the following results: in contrast to standard and oxygen-enriched float zone (FZ) silicon devices no space charge sign inversion was observed after irradiation. It is shown that the radiation-generated concentration of deep acceptors, dominating the behavior of n-type FZ diodes, is compensated by creation of shallow donors. Thus a positive space charge is maintained throughout the irradiation up to the highest fluence and even during prolonged elevated-temperature annealing cycles. Defect analysis studies using thermally stimulated current measurements attribute the effect to a damage-induced shallow donor at E C −0.23 eV. It is argued that, as in the case of thermal donors, oxygen dimers, out diffusing from the Cz substrate during the diode processing, are responsible precursers. Results from extensive annealing experiments at elevated temperatures are verified by comparison with prolonged room-temperature annealing. These results showed that in contrast to FZ detectors, which always have to be cooled, room-temperature storage during beam off periods of future elementary particle physics experiments would even be beneficial for n-type epi-silicon detectors. A dedicated experiment at CERN-PS had successfully proven this expectation. It was verified, that in such a scenario the depletion voltage for the epi-detector could always be kept at a moderate level throughout the full S-LHC operation (foreseen upgrade of the large hadron collider). Practically no difference with respect to FZ-silicon devices was found in the damage-induced bulk generation current. The charge trapping measured with 90 Sr electrons (mip's) is also almost identical to what was expected. A charge collection efficiency of 60% (2500 e) in 50 μm n-type epi-diodes after 24 GeV/ c proton irradiation with Φ eq =6.2×10 15 cm −2 was reported recently, independent of the operating temperature down to −20 °C.

Detectors processed on epitaxial silicon are a promising solution for the extreme radiation levels in the innermost tracking layers at future particle physics experiments as in the upgraded (S-LHC). In order to systematically investigate their radiation tolerance, sets of 25 and 50-μm-thick diodes had been irradiated with 24 GeV/ c protons up to fluences of Φ eq =10 16 cm −2 . The full depletion voltage was measured during full isothermal annealing cycles at both 60 and 80 °C. A voltage of only 290 V was measured for the 50 μm diodes after Φ eq =10 16 cm −2 . In contrast to likewise thin float zone (FZ) diodes, the depletion voltage in epi-devices decreases with annealing during foreseen operational and storage periods. Low-temperature storage during beam-off periods as inevitable for FZ devices could be avoided. The reverse annealing components reveal an overall similar functional time dependence as observed in FZ diodes. However, the most important stable component is drastically different. In contrast to the well-known negative space charge build up observed in FZ diodes, the behavior in epi-diodes can only be explained by an additional formation of positive space charge. The immense improvement of the radiation tolerance of epi-detectors is thus attributed to a compensation effect between acceptor generation and donor creation unique for the epi-material. Charge collection efficiency drops only to about 80% after Φ eq =6×10 15 cm −2 proving that epi-detectors are indeed adequate candidates for the tracking area at extremely large radiation levels.

Four different kinds of silicon materials (standard float zone—FZ, oxygen enriched FZ—DOFZ, Czochralski—Cz and thin epitaxial layers grown on Cz substrates—Epi/Cz) have been investigated in this work. They have been irradiated with 60Co-γ-radiation and 24 GeV/c protons. The differences in the changes observed in the effective doping concentration (Neff) after proton irradiation of Cz and Epi silicon can be explained by the balance between the formation of two types of defects—a deep acceptor (the I center, referred to as Ip in this paper in order to avoid any confusion with interstitials) and a shallow donor (the bistable donor (BD) complex). While the formation of the Ip center depends on the concentration of interstitial oxygen, the BD is generated in materials with high concentration of oxygen dimers. Following the generation of the IO2i defect—detected after low irradiation fluences only in Epi and Cz material—the average dimer concentration in 50 μm Epi/Cz was estimated to be of only 2.7 times lower than in Cz diodes. A value of ∼2.7×10−12 cm2 for the electron capture cross-section of the Thermal Double Donors (TDDs), present in the Cz material, was also measured for the first time. The positive space charge introduced by ionization of the BD centers in Epi diodes was directly determined from TSC experiments for two irradiation fluences. The determined values show a linear fluence dependence for the formation of BD centers. By taking into account the BD and the Ip center generation as well as the donor removal, the change of the effective doping concentration Neff at 20 °C in Epi/Cz and Cz diodes after an annealing time of 120 min at 60 °C can be explained up to a negative space charge introduction rate of ∼2.2×10−2 cm−1 thought to be determined by negatively charged clusters. Long-time annealing experiments at 80 °C have shown that the generation of BDs represents a stable damage.

Detectors processed on epitaxial silicon seem to be a viable solution for the extreme radiation levels in the innermost layers of tracking detectors at upgraded LHC (SLHC). A set of epitaxial pad detectors of 50 and 75 μ m thicknesses ( ρ = 50 Ω cm ) was irradiated with 24 GeV / c protons and reactor neutrons up to equivalent fluences of 10 16 cm - 2 . Charge collection for minimum ionizing electrons from a 90 Sr source was measured using a charge sensitive preamplifier and a 25 ns shaping circuit. The dependence of collected charge on annealing time and operation temperature was studied. Results were used to predict the performance of fine pitch pixel detectors proposed for SLHC.

The influence of preliminary treatment in hydrogen plasma on elimination of radiation defects and formation of thermal donors has been studied in detector structures made of standard and oxygenated float zone silicon has been studied. A new type of thermal donors has been found in as-treated diodes. These thermal donors are unstable and can be eliminated by heat-treatment at 200-250°C. After irradiation with 3.5 MeV electrons the detectors had been annealed at temperatures of 50-350 °C. It has been found that preliminary hydrogenation at 300 °C leads to disappearance of main vacancy-type radiation defects at lower annealing temperatures. The annealing of hydrogenated and irradiated crystals is accompanied by hydrogen redistribution and formation of hydrogen-related donors. Preliminary irradiation influences on both these processes.

The influence of preliminary treatment in hydrogen plasma on elimination of radiation defects and formation of thermal donors has been studied in detector structures made of standard float zone silicon. The detectors were irradiated with 3.5 MeV electrons and annealed at temperatures of 50–350 °C. It has been found that preliminary hydrogenation at 300 °C leads to disappearance of divacancies and vacancy–oxygen complexes at lower annealing temperatures. The annealing of hydrogenated and irradiated crystals is accompanied by hydrogen redistribution and formation of hydrogen-related donors.

Thin epitaxial layers grown on Cz substrates (Epi) and high resistivity Cz diodes have been irradiated with fluences of 2×10 14 cm −2 24 GeV protons. It is shown that the differences in the changes observed in the effective doping concentration ( N eff ) after irradiation of Epi silicon can be explained by the balance between the formation of two type of defects—a deep acceptor (the I center) and a shallow donor (the BD complex). The BD concentration in Epi material is evaluated to be ∼1.3×10 12 cm −3 .

Silicon test structures manufactured on different substrate materials (standard and oxygenated float-zone, magnetic and non-magnetic Czochralski, epitaxial silicon) have been irradiated with 900 MeV electrons up to a fluence of 6.1 × 10 15 e / cm 2 . Results are reported on the variation of the effective dopant concentration and of the leakage current density as a function of the electron fluence. The time evolution of the effective dopant concentration is also reported after thermal annealing cycles at 80 ∘ C .

Diodes manufactured on a thin and highly doped epitaxial silicon layer grown on a Czochralski silicon substrate have been irradiated by high energy lithium ions in order to investigate the effects of high bulk damage levels. This information is useful for possible developments of pixel detectors in future very high luminosity colliders because these new devices present superior radiation hardness than nowadays silicon detectors. The reverse current increase, the variation of the depletion voltage, and their annealing characteristics, as well as the charge collection properties, are presented and discussed.

Radiation-induced defects in silicon diodes were investigated after exposure to high doses of 60 Co gamma irradiation, using Deep Level Transient Fourier Spectroscopy and Thermally Stimulated Current methods. The main focus was on differences between standard and oxygen-enriched material and the impact of the observed defect generation on the diode properties. Two close to mid gap trapping levels and a bi-stable donor level have been found to be responsible for the main macroscopic changes both in standard and oxygen-enriched float zone diodes.

Radiation damage effects in silicon detectors under severe hadron and gamma-irradiation are surveyed, focusing on bulk effects. Both macroscopic detector properties (reverse current, depletion voltage and charge collection) as also the underlying microscopic defect generation are covered. Basic results are taken from the work done in the CERN-RD48 (ROSE) collaboration updated by results of recent work. Preliminary studies on the use of dimerized float zone and Czochralski silicon as detector material show possible benefits. An essential progress in the understanding of the radiation-induced detector deterioration had recently been achieved in gamma irradiation, directly correlating defect analysis data with the macroscopic detector performance.

Capacitance Deep Level Transient Spectroscopy (C-DLTS) measurements have been performed on standard and oxygen-doped silicon detectors manufactured from high-resistivity n-type float zone material with 〈1 1 1〉 and 〈1 0 0〉 orientation. Three different oxygen concentrations were achieved by the so-called diffusion oxygenated float zone (DOFZ) process initiated by the CERN-RD48 (ROSE) collaboration. Before the irradiation a material characterization has been performed. In contrast to radiation damage by neutrons or high-energy charged hadrons, were the bulk damage is dominated by a mixture of clusters and point defects, the bulk damage caused by 60 Co-γ-radiation is only due to the introduction of point defects. The dominant electrically active defects which have been detected after 60 Co-γ-irradiation by C-DLTS are the electron traps VO i , C i C s , V 2 (=/−), V 2 (−/0) and the hole trap C i O i . The main difference between standard and oxygenated silicon at low dose values can be seen in the introduction rate of C i C s compared to C i O i . For highly oxygenated silicon the introduction of C i C s is fully suppressed, while the sum of the introduction rates g (C i C s )+ g (C i O i ) is independent on the oxygen concentration.

Silicon detectors produced from materials with different resistivities and oxygen concentrations have been irradiated with energetic neutrons, protons and pions. Isothermal annealing studies have shown correlation between microscopic defect evolution and the macroscopic detector performance. It was found that the annealing behavior of the electron traps attributed to the single and double charged divacancy is strongly related to the current related damage parameter α. In both cases the isothermal evolution is independent of the oxygen and doping concentration in the material under investigation ( 2×10 14 O ] 18 cm −3 and 10 12 P ] 13 cm −3 ) and the absolute values do not depend on the particles used for the irradiation provided the fluence is properly normalized by the nonionizing energy loss (NIEL). In contrast to this result the introduction rates of the observed point defects VOi and CiCs were however found to depend on the particle type. Thus clear indication is given that the generation of point defects does not scale with NIEL. Compared to neutron irradiated samples the introduction rate after irradiation with charged hadrons was found to be higher by a factor around 2.

There is an on-going discussion whether floods are more frequent nowadays than in the past and whether they will increase in a future climate. To explore this for Sweden we merged observed time-series from 69 sites across the country (450 000 km2) for the past century with high-resolution dynamic scenario modeling of the up-coming century. The results show that the changes of daily annual high flows in Sweden oscillate between decades, but there is no significant trend for the past 100 years. A small tendency for high flows to decrease by 0.3–0.4% per decade in magnitude and 10-year flood frequency was noted, but not statistically significant. Temperature was found to be the strongest climate driver for river high-flows, as these are mainly related to snow melt in Sweden. Also in the future there will be oscillations between decades, but these were difficult to estimate as climate projections were not in phase with observations. However, in the long term, the daily annual high-flows may decrease by on average 1% per decade, mainly due to lower peaks from snow melt in the spring (–2% per decade) caused by higher temperatures and shorter snow season. On the contrary, autumn flows may increase by 3% per decade due to more intensive rainfall. This indicates a shift in flood generating processes in the future, with more influence of rain generated floods. This should be considered in reference data for design variables when adapting to climate change. Uncertainties related to the study are discussed in the paper, both for observed data and for the complex model chain of climate impact assessments in hydrology.

Hydrological forecasting is one of the most essential tasks in operational hydrology; however, predictions are usually subject to several sources of uncertainty (both epistemic and aleatory). Theseuncertainties can be due to, for example, inadequacies in the model structure and/or parameters, forcing data, initial conditions and updating procedures. Here, we analyse medium-scale (10 days) hydrological forecasts across 71 selected indicator stations in Sweden and aim to identify typical uncertainties in the forecasting production chain and ways to reduce them, and analyse different performance characteristics. In particular, the analysis is based on two operational systems using the HBV and S-HYPE hydrological models. We investigate the effect of autoregressive updating of the forecasted discharge, and of usingensemble instead of deterministic forecasts. The recently proposed Kling-Gupta Efficiency and its decomposed terms are used to identify the remaining uncertainty in different characteristics of the flow signal.Results show that uncertainty in operational hydrological forecasting can be significantly reduced by updating using an autoregressive method for discharge. This is particularly significant in the short lead time, due to the emphasis towards improving the volume error in the system. However, in this study, the use of the median ensemble forecast could not reduce the remaining epistemic uncertainty in terms of an improved model performance.

We present an investigation on the influence of the oxygen concentration on radiation-induced changes in the effective doping concentration of silicon detectors. Diodes fabricated from silicon with interstitial oxygen content ranging from below 2×10 14 to 9×10 17 cm −3 have been irradiated with fast neutrons up to a fluence of 2×10 15 cm −2 . Our main interest focused on the so-called stable damage component in the change of the effective doping concentration being of prime importance for the application of silicon detectors in high-energy physics experiments. We demonstrate, that with a high oxygen enrichment the donor removal is appreciably reduced, reaching a value of only 10% of the initial doping concentration for [O i ]=9×10 17 cm −3 , while for normal detector grade material with [O i ] below 5×10 16 cm −3 that value is 60–90%. Furthermore, we show that the fluence proportional introduction of stable acceptors is independent of the oxygen concentration with an averaged introduction rate of (1.49±0.03)×10 −2 cm −1 . Only one material was found exhibiting a significantly smaller value of about 0.6×10 −2 cm −1 and thus indicating the possibility to suppress the radiation-induced acceptor creation by material modification. Finally, we show that the experimental findings disagree in several important aspects with predictions made by microscopic defect kinetics models, leaving the physical background of some of the measured data as an open question.

An overview of the radiation-damage-induced problems connected with the application of silicon particle detectors in future high-energy physics experiments is given. Problems arising from the expected hadron fluences are summarized and the use of the nonionizing energy loss for normalization of bulk damage is explained. The present knowledge on the deterioration effects caused by irradiation is described leading to an appropriate modeling. Examples are given for a correlation between the change in the macroscopic performance parameters and effects to be seen on the microscopic level by defect analysis. Finally possible ways are out-lined for improving the radiation tolerance of silicon detectors either by operational conditions, process technology or defect engineering.

The leakage current increase of silicon detectors irradiated with fast neutrons was measured in the fluence range from 10 11 to 10 15 cm −2 for a wide range of different starting material. The oxygen concentration in the investigated silicon varied from 9×10 17 cm −3 to below 2×10 14 cm −3 and the carbon concentration from 2×10 16 cm −3 to below 5×10 15 cm −3 . Furthermore the resistivity differed from 100 Ω cm to 20 kΩ cm for the used n-type and from 400 Ω cm to 2 kΩ cm for the p-type silicon. It is found that up to the highest fluence the current-related damage parameter alpha is almost independent of the initial resistivity and impurity concentration. After irradiation a universal annealing behavior for all material is observed which unmistakably indicates that the microscopic defects underlying the generation of leakage current are of intrinsic origin. Furthermore it is shown that the parameterization of the annealing behavior at an elevated temperature (here 60°C) provides an excellent tool for comparing the so-called hardness factors of different irradiation sources. As an example the hardness factors for the 24 GeV/ c CERN proton synchrotron and the TRIGA research reactor in Ljubljana were determined to be 0.51 and 0.90, respectively.

We report on a correlation between a deep hole trap observed by TSC (Thermally Stimulated Current) and the so-called reverse annealing effect of the effective doping concentration in neutron-irradiated silicon detectors.

We present thermally stimulated current (TSC) spectra measured on asymmetric p-n-junctions fabricated from detector grade silicon. A multitude of characteristic deep levels generated by fast neutron-induced damage with fluences ranging from 10 12 to 10 14 cm −2 were observed. The TSC spectra were found to depend strongly on both the filling conditions and the electric field strength in the device. The filling of the deep levels has been investigated in detail by varying the current, temperature, and duration of the free carrier injection pulse. The corresponding observations in conjunction with a delayed heating analysis allow a tentative identification of the complex defects VO i , C i O i , C i C s , and the divacancy VV.