Abstract
The formation of stars above about 20 M⊙ and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity ...spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (>82 per cent) with masses above 16 M⊙ form close binary systems while this fraction rapidly drops to 20 per cent for stars of 3 M⊙. The binary fractions of O-type stars among different environment classes are: clusters (72 ± 13 per cent), associations (73 ± 8 per cent), field (43 ± 13 per cent) and runaways (69 ± 11 per cent). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69 per cent compared to 19-26 per cent in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.
•First experimental test of Kandori reputation labeling mechanism.•Theory suggests that a Kandori reputation mechanism can be used to sustain cooperation in the random pairwise matching prisoners’ ...dilemma.•Experiment data support this suggestion provided the mechanism is sufficiently transparent.•There is evidence that the participants used five behavioral strategies and learned to cooperate.
The evolution of cooperation has been the focus of intense research in the social sciences, natural sciences (especially biology), and even computer science. It has long been recognized that the possibility of future consequences is crucial to the emergence of rational cooperation. It was thought that random matching was isomorphic to one-shot play, but Kandori (1992) showed that a reputation labeling mechanism can be used to support cooperation in the random matching Prisoner Dilemma. We designed an experiment to test this result. We found that while the level of cooperation steadily declined without a reputation mechanism, with our color-coded reputation mechanism the level of cooperation steadily increased with experience. An econometric mixture model consisting of four reputation-conditioned strategies as well as a Level-0 type was fitted to the data. We cannot reject the hypothesis that the majority of subjects used one of these strategies and learned with experience.
The survival rates for testicular cancer are excellent; still, there is a lack of knowledge regarding important survivorship issues, such as sexual dysfunction and reproductive concerns.
The aim of ...this study was to investigate the prevalence and predictors of sexual dysfunction and reproductive concerns and the potential association between these issues in young men ∼2 years after a diagnosis of testicular cancer.
Data were collected from 111 men (response rate = 50%) diagnosed with testicular cancer at age 16–39. Patients were identified via the Swedish National Quality Registry for Testicular Cancer and approached with a survey, including standardized measures of sexual function, reproductive concerns, body image, and health-related quality of life. The survey was sent to participants approximately 2 years after their cancer diagnosis. Clinical variables were collected from the registry. Predictors were identified by multivariable linear regression analyses.
The main outcomes were sexual function, assessed with the Patient-Reported Outcomes Measurement Information System Sexual Function and Satisfaction measure version 2.0, and reproductive concerns, assessed with the Reproductive Concerns After Cancer scale.
Sexual dysfunction was reported by 26% of men, and a high level of reproductive concerns was reported by 28%. Lower satisfaction with sex life was associated with older age (β = −0.41), negative body image (β = −0.42), not having a partner (β = 4.8), and dissatisfaction with sex life before cancer (β = 8.31). Negative body image was associated with reproductive concerns in the dimensions of fertility potential (β = 0.06), partner disclosure (β = 0.08), and child’s health (β = 0.07), whereas having had fertility preservation predicted higher levels of concerns with regard to personal health (β = 0.52) and achieving pregnancy (β = 0.53). Clinical variables did not predict either sexual function or reproductive concerns.
Our results show that the majority of young men diagnosed with testicular cancer do not report sexual dysfunction or reproductive concerns 2 years after diagnosis. A sizeable minority, however, does report dysfunction or reproductive concerns, which should be recognized in the follow-up care of this population.
A strength of the study is the use of high-quality registry data and validated instruments. The lack of Swedish norms for sexual function and reproductive concerns is a possible limitation.
A subgroup of young men treated for testicular cancer report sexual dysfunction or reproductive concerns approximately 2 years after diagnosis. Factors associated with these issues seem to mainly be psychological, rather than medical, nature.
Ljungman L, Eriksson LE, Flynn KE, et al. Sexual Dysfunction and Reproductive Concerns in Young Men Diagnosed With Testicular Cancer: An Observational Study. J Sex Med 2019;16:1049–1059.
Summary
Objective
Cancer and its treatment in childhood and young adulthood can cause hypogonadism, leading to increased risk of long‐term morbidity and mortality. The aim of this study was to ...evaluate the risk of presenting with biochemical signs of hypogonadism in testicular cancer survivors (TCS) and male childhood cancer survivors (CCS) in relation to the type of treatment given.
Design
Case‐control study.
Patients
Ninety‐two TCS, 125 CCS (mean age 40 and median age 34 years, respectively; mean follow‐up time 9.2 and 24 years, respectively) and a corresponding number of age‐matched controls.
Measurements
Fasting morning blood samples were analysed for total testosterone (TT), follicle‐stimulating hormone (FSH) and luteinizing hormone (LH). The odds ratios (OR) for hypogonadism, defined as primary, secondary, compensated or ongoing androgen replacement, were calculated for TCS and CCS and for subgroups defined by diagnosis and treatment.
Results
Hypogonadism was found in 26% of CCS and 36% of TCS, respectively (OR: 2.1, P = .025 and OR = 2.3, P = .021). Among CCS, the OR was further increased in those given testicular irradiation (OR = 28, P = .004). Radiotherapy other than cranial or testicular irradiation plus chemotherapy, or cranial irradiation without chemotherapy, associated also with increased ORs (OR = 3.7, P = .013, and OR = 4.4, P = .038, respectively). Among TCS, those receiving >4 cycles of cisplatin‐based chemotherapy had OR = 17, P = .015.
Conclusions
Biochemical signs of testosterone deficiency are recognized as markers of decreased life expectancy. Thus, the risk of hypogonadism in TCS and CCS should be recognized and emphasizes the need of long‐term follow‐up for these men.
Many aquifers that are highly contaminated by arsenic in South and Southeast Asia are in the floodplains of large river networks. Under natural conditions, these aquifers would discharge into nearby ...rivers; however, large‐scale groundwater pumping has reversed the flow in some areas so that rivers now recharge aquifers. At a field site near Hanoi Vietnam, we find river water recharging the aquifer becomes high in arsenic, reaching concentrations above 1000 µg/L, within the upper meter of recently (< ∼10 years) deposited riverbed sediments as it is drawn into a heavily pumped aquifer along the Red River. Groundwater arsenic concentrations in aquifers adjacent to the river are largely controlled by river geomorphology. High (>50 µg/L) aqueous arsenic concentrations are found in aquifer regions adjacent to zones where the river has recently deposited sediment and low arsenic concentrations are found in aquifer regions adjacent to erosional zones. High arsenic concentrations are even found adjacent to a depositional river reach in a Pleistocene aquifer, a type of aquifer sediment which generally hosts low arsenic water. Using geochemical and isotopic data, we estimate the in situ rate of arsenic release from riverbed sediments to be up to 1000 times the rates calculated on inland aquifer sediments in Vietnam. Geochemical data for riverbed porewater conditions indicate that the reduction of reactive, poorly crystalline iron oxides controls arsenic release. We suggest that aquifers in these regions may be susceptible to further arsenic contamination where riverine recharge drawn into aquifers by extensive groundwater pumping flows through recently deposited river sediments before entering the aquifer.
Key Points:
Rates of arsenic release from young riverbed sediments are up to 1000 times the release rates from aquifer sediment
River recharge induced by groundwater pumping may contaminate previously safe aquifers with arsenic
Riverbank geomorphology can influence groundwater arsenic concentrations in aquifers adjacent to rivers
Little is known regarding sperm production following adjuvant treatment in testicular cancer (TC) clinical stage I (CS I) patients.
A total of 182 TC patients aged 18–50 years were prospectively ...included during 2001–2006 at any given time within 5 years of orchiectomy. Semen samples were delivered postorchiectomy but before further treatment, 6, 12, 24, 36 and 60 months (T0–T60) after completed therapy. Total sperm number (TSN) and sperm concentration (SC) were used as measurements of testicular function. Four groups according to treatment modality were identified; Radiotherapy; To a total dose of 25.2 Gy to the infradiaphragmal paraaortic and ipsilateral iliac lymph nodes (RT, N = 70), one cycle of adjuvant BEP (bleomycin, etoposide, cisplatin, 5 day regimen) (BEP, N = 62), one cycle of adjuvant carboplatin AUC 7 (Carbo, N = 22), and patients managed by surveillance (SURV, N = 28).
In the cross-sectional analysis, a significant but transient drop in mean TSN and mean SC (T0–T60) was seen at T6 after radiotherapy. Apart from a significant increase in mean SC at T12 compared with baseline, no significant differences were observed in the other treatment groups. In 119 patients delivering 3 or more samples, values in TSN and SC were rather stable over time. Azoospermic patients (N = 11) were observed in most treatment groups except for in the BEP group. During follow-up, one azoospermic patient belonging to the Carbo group became normospermic.
No clinically significant long-term effect on TSN or SC associated with adjuvant treatment in TC CSI patients was found. However, as patients may have low sperm counts before orchiectomy as well as after adjuvant treatment, we offer sperm banking before orchiectomy as assisted reproductive measures may be necessary regardless of treatment given.
Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of south and southeast Asia exposes an estimated population of over a hundred million people to toxic levels ...of arsenic. Holocene aquifers are the source of widespread arsenic poisoning across the region. In contrast, Pleistocene sands deposited in this region more than 12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination more than 120 metres from a Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16-20-fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in south and southeast Asia as a consequence of increasing levels of groundwater pumping may have been delayed by the retardation of arsenic transport.
Human activity has led to excess phosphorus (P) concentrations and the continued eutrophication of coastal and freshwaters across the United States (US). Developing more effective P management policy ...requires a comprehensive understanding of P sources in the environment. Public water systems across the United States widely dose water with phosphate (PO4) in order to control the corrosion of lead and copper within their distribution networks. Using public water system PO4 dosing facility data and target PO4‐P dosing concentrations, we estimate that PO4 dosing added 4–14.9 kt PO4‐P yr−1 into the US water distribution network in 2015. Using estimates of public water supply inputs and domestic water deliveries, we estimate that 0.7–2.6, and 0.8–3.1 kt PO4‐P yr−1 were then lost from the network due to watermains leakage and outdoor water use, respectively. After accounting for these fluxes, we estimate that 9.3 kt PO4‐P yr−1 was then returned to wastewater treatment plants (WWTPs) and accounted for up to 2.7% of the national WWTP influent P load. As sources of P to the environment, lower and upper estimates of combined watermains leakage and outdoor water use PO4‐P fluxes exceeded P loads to surface waterbodies from documented point sources across 461–541 counties. The exceedance of these fluxes above other major components of the US P‐budget emphasizes the need to include them in P source apportionment studies, both across the US and in other countries where public water supplies are dosed with PO4.
Key Points
Leakage and outdoor water use release up to 17% and 21% of the 14.9 kt PO4‐P yr−1 added to US public water supply for corrosion control
Combined leakage and outdoor water use PO4‐P fluxes exceed point source P inputs to freshwaters across 541 counties
These fluxes should be considered in P source apportionment studies and could inform localized P management practices
A stylized fact from laboratory experiments is that there is much heterogeneity in human behavior. We present and demonstrate a computationally practical non-parametric Bayesian method for ...characterizing this heterogeneity. In addition, we define the concept of behaviorally distinguishable parameter vectors, and use the Bayesian posterior to say what proportion of the population lies in meaningful regions. These methods are then demonstrated using laboratory data on lottery choices and the rank-dependent expected utility model. In contrast to other analyses, we find that 79% of the subject population is not behaviorally distinguishable from the ordinary expected utility model.
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