Statistical downscaling of a climate simulation of the last glacial cycle : Temperature and precipitation over Europe

Peer reviewe

Advanced Concepts in Josephson Junction Reflection Amplifiers

Low-noise amplification atmicrowave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature $T_{q} = \hbar {\omega}/2k_{B}$. Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at $2\omega$ pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at $\omega$.Comment: 9 pages, 6 figure

Evidence of Cooper pair pumping with combined flux and voltage control

We have experimentally demonstrated pumping of Cooper pairs in a single-island mesoscopic structure. The island was connected to leads through SQUID (Superconducting Quantum Interference Device) loops. Synchronized flux and voltage signals were applied whereby the Josephson energies of the SQUIDs and the gate charge were tuned adiabatically. From the current-voltage characteristics one can see that the pumped current increases in 1e steps which is due to quasiparticle poisoning on the measurement time scale, but we argue that the transport of charge is due to Cooper pairs.Comment: 4 page

Limited dispersal and an unexpected aggression pattern in a native supercolonial ant

Abstract Understanding how social groups function requires studies on how individuals move across the landscape and interact with each other. Ant supercolonies are extreme cooperative units that may consist of thousands of interconnected nests, and their individuals cooperate over large spatial scales. However, the inner structure of suggested supercolonial (or unicolonial) societies has rarely been extensively studied using both genetic and behavioral analyses. We describe a dense supercolony-like aggregation of more than 1,300 nests of the ant Formica (Coptoformica) pressilabris. We performed aggression assays and found that, while aggression levels were generally low, there was some aggression within the assumed supercolony. The occurrence of aggression increased with distance from the focal nest, in accordance with the genetically viscous population structure we observe by using 10 DNA microsatellite markers. However, the aggressive interactions do not follow any clear pattern that would allow specifying colony borders within the area. The genetic data indicate limited gene flow within and away from the supercolony. Our results show that a Formica supercolony is not necessarily a single unit but can be a more fluid mosaic of aggressive and amicable interactions instead, highlighting the need to study internest interactions in detail when describing supercolonies.Peer reviewe

Effects of melting ice sheets and orbital forcing on the early Holocene warming in the extratropical Northern Hemisphere

Peer reviewe

Human population dynamics in Europe over the Last Glacial Maximum

The severe cooling and the expansion of the ice sheets during the Last Glacial Maximum (LGM), 27,000-19,000 y ago (27-19 ky ago) had a major impact on plant and animal populations, including humans. Changes in human population size and range have affected our genetic evolution, and recent modeling efforts have reaffirmed the importance of population dynamics in cultural and linguistic evolution, as well. However, in the absence of historical records, estimating past population levels has remained difficult. Here we show that it is possible to model spatially explicit human population dynamics from the pre-LGM at 30 ky ago through the LGM to the Late Glacial in Europe by using climate envelope modeling tools and modern ethnographic datasets to construct a population calibration model. The simulated range and size of the human population correspond significantly with spatiotemporal patterns in the archaeological data, suggesting that climate was a major driver of population dynamics 30-13 ky ago. The simulated population size declined from about 330,000 people at 30 ky ago to a minimum of 130,000 people at 23 ky ago. The Late Glacial population growth was fastest during Greenland interstadial 1, and by 13 ky ago, therewere almost 410,000 people in Europe. Even during the coldest part of the LGM, the climatically suitable area for human habitation remained unfragmented and covered 36% of Europe.Peer reviewe

Evolution of dispersal in ants (Hymenoptera: Formicidae) : a review on the dispersal strategies of sessile superorganisms

The extreme diversity of dispersal strategies in ants is unique among terrestrial animals. The nature of ant colonies as social, perennial, and sessile superorganisms is the basis for understanding this diversity, together with the inclusive-fitness framework for social evolution. We review ant dispersal strategies, with the aim of identifying future research directions on ant dispersal and its evolution. We list ultimate and proximate determinants of dispersal traits and the ecological and evolutionary consequences of dispersal for population structures and dynamics, as well as species communities. We outline the eco-evolutionary feedbacks between the multitude of traits affecting dispersal evolution and the likely evolutionary routes and ecological drivers in transitions among the diverse ant dispersal strategies. We conclude by presenting a research framework to fill the gaps in current knowledge, including comparative studies of colony life histories and population structures and theoretical models of the eco-evolutionary dynamics affecting dispersal, in an inclusive-fitness framework.Peer reviewe

Survival and mortality of elderly men with localized prostate cancer managed with primary androgen deprivation therapy or by primary observation

Background Androgen deprivation therapy (ADT) remains a primary treatment for localized prostate cancer (PCa) even though there is no evidence that its use is beneficial in the absence of curative treatment. Methods Men aged >= 70 years (n = 16,534) diagnosed with localized PCa from 1985 to 2014 and managed either with primary observation or ADT in the absence of curative treatment were included. The cases were identified from the population-based Finnish Cancer Registry. We estimated the standardized mortality ratios (SMR) for overall mortality by treatment group. We determined the relative risk (RR) of PCa-specific mortality (PCSM) and other-cause mortality between the two treatment groups. Survival was determined using the life table method. Two age groups (70-79 years and >= 80 years) and three calendar time cohorts (1985-1994, 1995-2004, and 2005-2014) were compared following adjustment of propensity score matching between the treatment groups with four covariates (age, year of diagnosis, educational level, and hospital district). Follow-up continued until death or until December 31, 2015. Results Patients in the observation group had lower overall SMRs than those in the ADT group in both age cohorts over the entire study period. PCSM was higher in men aged 70-79 years undergoing primary ADT compared to those managed by observation only (RR: 1.70, 95% confidence interval [CI]: 1.29-2.23 [1985-1994]; RR 1.55, 95% CI: 1.35-1.84 [1995-2004]; and RR 2.71, 95% CI: 2.08-3.53 [2005-2014]); p = 0.005 for periodic trend. A similar trend over time was also observed in men aged > 80 years; (p for age-period interaction = 0.237). Overall survival was also higher among men in their 70's managed by observation compared to those undergoing ADT. Conclusions Primary ADT within four months period from diagnosis is not associated with improved long-term overall survival or decreased PCSM compared to primary conservative management for men with localized PCa. However, this observational study's conclusions should be weighted with confounding factors related to cancer aggressiveness and comorbidities.Peer reviewe