Environmental drivers of increased ecosystem respiration in a warming tundra.

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5-7. This hampers the accuracy of global land carbon-climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9-2.0 °C] in air and 0.4 °C [CI 0.2-0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22-38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Progesterone supplementation in natural cycles improves live birth rates after embryo transfer of frozen-thawed embryos-a randomized controlled trial.

STUDY QUESTION: Does supplementation with vaginal tablets of progesterone after frozen-thawed embryo transfer in natural cycles improve the live birth rate? SUMMARY ANSWER: Supplementation with vaginal tablets of progesterone after frozen-thawed embryo transfer in natural cycles significantly improves the number of live births. WHAT IS KNOWN ALREADY: Progesterone supplementation during luteal phase and early pregnancy may improve the number of live births after frozen-thawed embryo transfer. However, due to the limited number of previous studies, being mainly retrospective, evidence is still limited. STUDY DESIGN, SIZE, DURATION: This is a prospective randomized controlled trial, performed at two university clinics. In total, 500 subjects were randomized with a 1:1 allocation into two groups, during the period February 2013 to March 2018. Randomization was performed after a frozen embryo transfer in a natural cycle by use of opaque sealed envelopes. The primary outcome was live birth rate; secondary outcomes were pregnancy, biochemical pregnancy, clinical pregnancy and miscarriage rate, and if there was a possible association between the serum progesterone concentration on the day of embryo transfer and live birth rate. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women, receiving embryo transfer in natural cycles participated in the study. The embryos were frozen on Day 2, 3, 5 or 6. In total, 672 women having regular menstrual cycles were invited to participate in the study; of those, 500 agreed to participate and 488 were finally included in the study. Half of the study subjects received progesterone supplementation with progesterone vaginal tablets, 100 mg twice daily, starting from the day of embryo transfer. The other half of the subjects were not given any treatment. Blood samples for serum progesterone measurements were collected from all subjects on the day of embryo transfer. MAIN RESULTS AND THE ROLE OF CHANCE: There were no differences in background characteristics between the study groups. In the progesterone supplemented group, 83 of 243 patients (34.2%) had a live birth, compared to 59 of 245 patients (24.1%) in the control group (odds ratio 1.635, 95% CI 1.102-2.428, P = 0.017*). The number of pregnancies was 104 of 243 (42.8%) and 83 of 245 (33.9%), respectively (odds ratio 1.465, 95% CI 1.012-2.108, P = 0.049*) and the number of clinical pregnancies was 91 of 243 (37.4%) and 70 of 245 (28.6%), respectively (odds ratio 1.497, 95% CI 1.024-2.188, P = 0.043*). There were no significant differences in biochemical pregnancy rate or miscarriage rate. There was no correlation between outcome and serum progesterone concentration. LIMITATIONS, REASONS FOR CAUTION: The study was not blinded because placebo tablets were not available. Supplementation started on embryo transfer day, regardless of the age of the embryos, which resulted in a shorter supplementation time for Day 5/6 embryos compared to Day 2/3 embryos. WIDER IMPLICATIONS OF THE FINDINGS: Supplementation with progesterone in natural cycles improved the number of live births after frozen-thawed embryo transfer and should therefore be considered for introduction in clinical routine. STUDY FUNDING/COMPETING INTEREST(S): The study was funded by Uppsala University, the Uppsala-Family Planning Foundation, and Ferring Pharmaceuticals AB, Malmö, Sweden. The authors have no personal conflicting interests to declare. TRIAL REGISTRATION NUMBER: NL4152. TRIAL REGISTRATION DATE: 5 December 2013. DATE OF FIRST PATIENT'S ENROLMENT: 18 February 2013.

Efficacy of annealing and fabrication parameters on photo-response of SiGe in TiO2 matrix.

SiGe nanoparticles dispersed in a dielectric matrix exhibit properties different from those of bulk and have shown great potential in devices for application in advanced optoelectronics. Annealing is a common fabrication step used to increase crystallinity and to form nanoparticles in such a system. A frequent downside of such annealing treatment is the formation of insulating SiO2 layer at the matrix/SiGe interface, degrading the optical properties of the structure. An annealing process that could bypass this downside would therefore be of great interest. In this work, a short-time furnace annealing of a SiGe/TiO2 system is applied to obtain SiGe nanoparticles without formation of the undesired SiO2 layer between the dielectric matrix (TiO2) and SiGe. The structures were prepared by depositing alternate layers of TiO2 and SiGe films, using direct-current magnetron sputtering technique. A wide range spectral response with a response-threshold up to ∼1300 nm was obtained, accompanied with an increase in photo-response of more than two-orders of magnitude. Scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy and grazing incidence x-ray diffraction were used to analyze the morphological changes in respective structures. Photoconductive properties were studied by measuring photocurrent spectra using applied dc-voltages at various temperatures.

Comparing resonant photon tunneling via cavity modes and Tamm plasmon polariton modes in metal-coated Bragg mirrors.

Resonant photon tunneling was investigated experimentally in multilayer structures containing a high-contrast (TiO(2)/SiO(2)) Bragg mirror capped with a semitransparent gold film. Transmission via a fundamental cavity resonance was compared with transmission via the Tamm plasmon polariton resonance that appears at the interface between a metal film and a one-dimensional photonic bandgap structure. The Tamm-plasmon-mediated transmission exhibits a smaller dependence on the angle and polarization of the incident light for similar values of peak transmission, resonance wavelength, and finesse. Implications for transparent electrical contacts based on resonant tunneling structures are discussed.

Who becomes a sperm donor: personality characteristics in a national sample of identifiable donors.

OBJECTIVE: To study the personality characteristics of identifiable sperm donors in a national sample in comparison with the same characteristics of a control group. DESIGN: Descriptive study. SETTING: All clinics (n=7) performing gamete donation in Sweden. POPULATION: All Swedish sperm donors recruited during 2005-08. An age-matched group of Swedish men served as controls. METHODS: Standardised questionnaires were used to measure personality. MAIN OUTCOME MEASURES: Demographics and the Temperament and Character Inventory (TCI). RESULTS: The mean age of the donors was 33.8±7.8 years (18-56 years). About one-third (36.5%) of the donors had biological children of their own. With regard to personality, significant differences were present on harm avoidance, with lower means for sperm donors (P=0.002, 95% CI -3.74 to -0.85), and on self-directedness and cooperativeness, with higher means for donors (P=0.002, 95% CI 0.97-4.19; P=0.001; 95% CI 0.75-2.95, respectively), compared with controls. This indicates that the donors in general feel less worried and suffer less from uncertainty, shyness and fatigability than controls. They also perceive themselves as being autonomous, with a capacity to take responsibility, to behave in a goal-directed manner, to be resourceful and self-acceptant, and to behave in a manner guided by meaningful values and goals. Furthermore, they describe themselves as being well integrated in humanity or society, and having a good capacity for identification with and acceptance of other people. CONCLUSIONS: The screening process at the clinics seems to generate a group of stable, mature and well-integrated donors, and this is a promising result for the future.

Ar+ and Xe+ velocities near the presheath-sheath boundary in an Ar/Xe discharge.

The velocities of Ar+ and Xe+ ions near the presheath-sheath boundary in an Ar/Xe discharge are studied by particle-in-cell Monte Carlo simulation. For a pure argon discharge the argon ion has almost the same velocity profile as it does in the mixture of argon and xenon. Similarly, for a xenon discharge the xenon ion has almost the same velocity profile as it does in the mixture of argon and xenon. The ion speed at the sheath-presheath boundary is the same for an ion in a pure argon or xenon discharge and for the same ion in a mixture of argon and xenon. We conclude that, in our simulation, each ion reaches its own Bohm speed at the presheath-sheath interface.

Personality characteristics in a Swedish national sample of identifiable oocyte donors.

OBJECTIVE: To study the personality characteristics of identifiable oocyte donors in a national sample in comparison with normal values. DESIGN: Descriptive study. SETTING: All Swedish donation programmes. SAMPLE: In total, 181 women out of 221 donors recruited during 2005-2008. METHODS: Standardised questionnaires were used to measure personality characteristics. MAIN OUTCOME MEASURE: Demographics, temperament and character inventory (TCI). RESULTS: The majority (69%) of the donors had biological children of their own. The results from the TCI indicate that the oocyte donors were all within the normal range of character. With regard to personality, a significant difference was evident between the two groups: oocyte donors showed lower means for harm avoidance and higher scores for persistence than the controls. This indicates that the donors felt less worried, and displayed a lower level of fear of uncertainty, shyness and fatiguability, and a higher level of persistence, than the controls. In the present sample, 29 (16%) of the donors were so-called 'known donors', that is the recipient couples and the donors were known to each other. 'Known donors' displayed a mature and stable character. CONCLUSION: We found that the women who had been accepted for inclusion in this nationwide oocyte donor programme were all well adjusted and mature.

Digital smoothing of the Langmuir probe I-V characteristic.

Electrostatic probes or Langmuir probes are the most common diagnostic tools in plasma discharges. The second derivative of the Langmuir probe I-V characteristic is proportional to the electron energy distribution function. Determining the second derivative accurately requires some method of noise suppression. We compare the Savitzky-Golay filter, the Gaussian filter, and polynomial fitting to the Blackman filter for digitally smoothing simulated and measured I-V characteristics. We find that the Blackman filter achieves the most smoothing with minimal distortion for noisy data.

A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements.

We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks.

Characterizing discrete subsets of polycystic ovary syndrome as defined by the Rotterdam criteria: the impact of weight on phenotype and metabolic features.

CONTEXT: The Rotterdam criteria for polycystic ovary syndrome (PCOS) defines discrete subgroups whose phenotypes are not yet clear. OBJECTIVE: The phenotypic characteristics of women in the PCOS subgroups defined by the Rotterdam criteria were compared. DESIGN: The study was observational. SETTING: Subjects were studied in an outpatient setting in Boston and Reykjavik. PATIENTS: Four subgroups of subjects with PCOS defined by 1) irregular menses (IM), hyperandrogenism (HA), and polycystic ovary morphology (PCOM, n = 298); 2) IM/HA (n = 7); 3) HA/PCOM (n = 77); and 4) IM/PCOM (n = 36) and a group of controls (n = 64), aged 18-45 yr, were examined. INTERVENTION: Subjects underwent a physical exam; fasting blood samples for androgens, gonadotropins, and metabolic parameters; and a transvaginal ultrasound. MAIN OUTCOME MEASURES: The phenotype was compared between groups. RESULTS: Ninety-seven percent of women with IM/HA had PCOM. Therefore, the groups with and without PCOM were combined. The Ferriman-Gallwey score and androgen levels were highest in the hyperandrogenic groups (IM/HA and HA/PCOM), whereas ovarian volume was higher in all PCOS subgroups compared with controls, as expected based on the definitions of the PCOS subgroups. Body mass index and insulin levels were highest in the IM/HA subgroup. CONCLUSIONS: Subjects with PCOS defined by IM/HA are the most severely affected women on the basis of androgen levels, ovarian volumes, and insulin levels. Their higher body mass index partially accounts for the increased insulin levels, suggesting that weight gain exacerbates the symptoms of PCOS.

Defining constant versus variable phenotypic features of women with polycystic ovary syndrome using different ethnic groups and populations.

CONTEXT: The phenotype of women with polycystic ovary syndrome (PCOS) is variable, depending on the ethnic background. OBJECTIVE: The phenotypes of women with PCOS in Iceland and Boston were compared. DESIGN: The study was observational with a parallel design. SETTING: Subjects were studied in an outpatient setting. PATIENTS: Women, aged 18-45 yr, with PCOS defined by hyperandrogenism and fewer than nine menses per year, were examined in Iceland (n = 105) and Boston (n = 262). INTERVENTION: PCOS subjects underwent a physical exam, fasting blood samples for androgens, gonadotropins, metabolic parameters, and a transvaginal ultrasound. MAIN OUTCOME MEASURES: The phenotype of women with PCOS was compared between Caucasian women in Iceland and Boston and among Caucasian, African-American, Hispanic, and Asian women in Boston. RESULTS: Androstenedione (4.0 +/- 1.3 vs. 3.5 +/- 1.2 ng/ml; P < 0.01) was higher and testosterone (54.0 +/- 25.7 vs. 66.2 +/- 35.6 ng/dl; P < 0.01), LH (23.1 +/- 15.8 vs. 27.6 +/- 16.2 IU/liter; P < 0.05), and Ferriman Gallwey score were lower (7.1 +/- 6.0 vs. 15.4 +/- 8.5; P < 0.001) in Caucasian Icelandic compared with Boston women with PCOS. There were no differences in fasting blood glucose, insulin, or homeostasis model assessment in body mass index-matched Caucasian subjects from Iceland or Boston or in different ethnic groups in Boston. Polycystic ovary morphology was demonstrated in 93-100% of women with PCOS in all ethnic groups. CONCLUSIONS: The data demonstrate differences in the reproductive features of PCOS without differences in glucose and insulin in body mass index-matched populations. These studies also suggest that measuring androstenedione is important for the documentation of hyperandrogenism in Icelandic women. Finally, polycystic ovary morphology by ultrasound is an almost universal finding in women with PCOS as defined by hyperandrogenism and irregular menses.

Symbiotic and saprophytic survival of three unmarked Rhizobium leguminosarum biovar trifolii strains introduced into the field.

The symbiotic and saprophytic persistence of three unmarked Rhizobium leguminosarum biovar trifolii (Rlt) strains introduced into a field site in Iceland were followed. This site was free of clover cultivation and initially devoid of clover-nodulating rhizobia as tested by nodulation studies. Nodule occupancy by strains was identified based on their distinct ERIC-polymerase chain reaction (PCR) DNA fingerprint patterns. The survival and persistence of the individual strains in soil were monitored by the quantitative real-time PCR (qRT-PCR) assay, targeting the host-specific nodE gene. The most dominant strain in the nodule population, Rlt 20-15, showed relatively less saprophytic survival ability and maintained high numbers only in the presence of the appropriate host plant. Conversely, the minor nodule occupant, Rlt 32-28, persisted in soil at a relatively higher abundance both in the presence of its host legumes and in the presence of a non-host grass. The qRT-PCR assay was successfully applied to quantify rhizobial strains directly in soil without culturing or nodulation. However, the assay demonstrated less sensitivity compared with the plant infection most-probable-number (MPN) method for estimating the population size of rhizobia in soil. The quantitative detection limit of our qRT-PCR assays was 1 x 10(3) cells per gram of soil, as opposed to the MPN test which has a detection limit of 10 cells per gram of soil.

Respiration as the main determinant of carbon balance in European forests.

Carbon exchange between the terrestrial biosphere and the atmosphere is one of the key processes that need to be assessed in the context of the Kyoto Protocol. Several studies suggest that the terrestrial biosphere is gaining carbon, but these estimates are obtained primarily by indirect methods, and the factors that control terrestrial carbon exchange, its magnitude and primary locations, are under debate. Here we present data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, which confirm that many European forest ecosystems act as carbon sinks. The annual carbon balances range from an uptake of 6.6 tonnes of carbon per hectare per year to a release of nearly 1 t C ha(-1) yr(-1), with a large variability between forests. The data show a significant increase of carbon uptake with decreasing latitude, whereas the gross primary production seems to be largely independent of latitude. Our observations indicate that, in general, ecosystem respiration determines net ecosystem carbon exchange. Also, for an accurate assessment of the carbon balance in a particular forest ecosystem, remote sensing of the normalized difference vegetation index or estimates based on forest inventories may not be sufficient.

European multicenter study on LOH of APOC3 at 11q23 in 766 breast cancer patients: relation to clinical variables. Breast Cancer Somatic Genetics Consortium.

High frequencies of loss of heterozygosity (LOH) in chromosome 11q22-qter have been observed in various malignancies, including breast cancer. Previous studies on breast carcinomas by Winqvist et al (Cancer Res 55: 2660-2664) have indicated that a survival factor gene is located in band 11q23, and that the highly informative microsatellite polymorphism at the APOC3 locus would be a suitable tool to perform more extensive LOH studies. In this European multicentre study, we have examined the occurrence of APOC3 LOH and evaluated the effect of LOH of this chromosomal subregion on the clinical behaviour of the disease in a cohort of 766 breast cancer patients in more detail. LOH for APOC3 was found in 42% of the studied tumours, but it was not found to be significantly associated with any of the studied clinical variables, including cancer-specific survival time or survival time after recurrent/metastatic disease. According to the present findings, the putative survival factor gene on 11q23 is not located close enough to the APOC3 gene, but apparently at a more proximal location.

[Bilateral oophorectomy before menopause. Late effects on quality of life, lipid metabolism and bone mass.].

OBJECTIVE: Oophorectomy in premenopausal women may profoundly affect health. This study was done to investigate whether it had influenced the quality of life, lipid metabolism and bone mass if removal of the ovaries in premenopausal women was performed more than 15 years ago. MATERIAL AND METHODS: Operation records from the Department of Obstetrics and Gynecology at the National University Hospital, Reykjvík, were scruti-nized to find all women who during 1977-1984 had a bilateral oophorectomy performed at less than 47 years of age at the time of operation. A control group of age-matched women, who during the same period had undergone a hysterectomy with preservation of the ovaries, was chosen. Women with malignant and chronic disabling diseases were excluded. The participants answered 36 standardized questions relating to menopausal symptoms, hormonal use and smo-king. Mesurements of total serum cholesterol, HDL (high density lipoprotein) and LDL (low density lipoprotein) cholesterol, triglycerides and calcium and fasting urine calcium and creatinine, were performed. Bone mineral density was assessed by dual energy X-ray absorptiometry in the lumbar spine, left hip and femoral neck. RESULTS: Thirty-four patients and equally many controls were identified. Fifty women agreed to participate, but two did not attend for the investigation, giving a total of 26 cases and 22 controls. Mean age at the time of operation was 43.3 years for cases and 43.5 and controls. The difference in the duration of hormone use (11.6 and 8.9 years) was not significant. Of the 36 questions on climacteric symptoms there was a significant difference between the groups in only one. Cases and controls were not different with regard to serum lipids and bone mineral density. Mean values of bone mineral density in both groups were within the normal limits for an age-matched general population. CONCLUSIONS: Women who underwent removal of the ovaries before 47 years of age, more than 15 years later, were not shown to have suffered more from longterm effects of estrogen deficiency than age-matched women who had undergone hysterectomy with preservation of the ovaries. A relatively long duration of estrogen use may be the main reason for this outcome.

High incidence of loss of heterozygosity in breast tumors from carriers of the BRCA2 999del5 mutation.

Germ-line mutation in the BRCA2 gene confers an increased risk of breast cancer. An elevation of additional genetic defects in tumors of patients with germ-line mutation in the BRCA2 gene compared with sporadic breast tumors has been reported. To evaluate the nature of the difference, we did detailed mapping of chromosomes 1p, 3p, 6q, 11, 13q, 16q, 17, and 20q, using microsatellite markers. We found that the frequency of loss of heterozygosity was similar at some chromosomal regions in the BRCA2 999del5 and sporadic tumors but significantly different at others. These others include chromosomal arms 3p, 6q, 11p, 11q, 13q, and 17p. Loss of heterozygosity mapping suggests that the same chromosome regions are involved in both tumor groups but at elevated frequencies in BRCA2 999del5 tumors. This higher frequency of genetic aberrations could pinpoint genes that selectively promote tumor progression in individuals predisposed to breast cancer due to the BRCA2 999del5 germ-line mutation. Accumulation of somatic genetic changes during tumor progression may follow a specific and more aggressive pathway of chromosome damage in these individuals.

Mapping loss of heterozygosity at chromosome 13q: loss at 13q12-q13 is associated with breast tumour progression and poor prognosis.

Several chromosome regions exhibit loss of heterozygosity (LOH) in human breast carcinoma and are thought to harbour tumour suppressor genes (TSG). At chromosome 13q, two TSGs have been identified, RB1 at 13q14 and BRCA2 at 13q12-q13. In this study, 139 sporadic breast tumours were analysed with 18 polymorphic microsatellite markers for detailed mapping of LOH at chromosome 13q and evaluation of an association with known progression factors. LOH with at least one marker was observed in 71 (51%) of the tumours analysed. The deletion mapping indicated three LOH target regions, 13q12-q13, 13q14 and 13q31-q34. LOH at chromosome 13q12-q13 was associated with low progesterone receptor content, a high S phase fraction and aneuploidy. Multivariate analysis adjusting for lymph node involvement and S phase fraction showed that patients with tumours exhibiting LOH at 13q12-q13 have a 3-4-fold increased risk of recurrence and death compared with other patients. Our results suggest there are at least three separate LOH target regions at chromosome 13q and inactivation of one or more genes at chromosome 13q12-q13 results in poor prognosis for breast cancer patients.