5 research outputs found
Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter
Climate change and human pressures are changing the global distribution and the exâ
tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the
global river network area. IRES are characterized by periods of flow cessation, during
which channel substrates accumulate and undergo physicoâchemical changes (preconâ
ditioning), and periods of flow resumption, when these substrates are rewetted and
release pulses of dissolved nutrients and organic matter (OM). However, there are no
estimates of the amounts and quality of leached substances, nor is there information
on the underlying environmental constraints operating at the global scale. We experiâ
mentally simulated, under standard laboratory conditions, rewetting of leaves, riverâ
bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES
from five major climate zones. We determined the amounts and qualitative characterâ
istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds.
In addition, we evaluated the variance in leachate characteristics in relation to selected
environmental variables and substrate characteristics. We found that sediments, due
to their large quantities within riverbeds, contribute most to the overall flux of disâ
solved substances during rewetting events (56%â98%), and that flux rates distinctly
differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contribâ
uted most to the areal fluxes. The largest amounts of leached substances were found
in the continental climate zone, coinciding with the lowest potential bioavailability of
the leached OM. The opposite pattern was found in the arid zone. Environmental variâ
ables expected to be modified under climate change (i.e. potential evapotranspiration,
aridity, dry period duration, land use) were correlated with the amount of leached subâ
stances, with the strongest relationship found for sediments. These results show that
the role of IRES should be accounted for in global biogeochemical cycles, especially
because prevalence of IRES will increase due to increasing severity of drying event
FörÀldraskap och neuropsykiatriskt funktionshinder : upplevelse och pÄverkan av diagnos
The aim in the study is to search for a deeper understanding of how parents experience a neurological diagnose of the child and how this affects the parenthood. Parenthood was seen in a systemtheoretical perspective as a social construction. The narrative method was used in two lifestory parentinterviews. The analysis was made from parenthood. The result formed stories about parenthood with children having neuropsyciatric functional disability who even came to be a womanâs struggle. Two stories became central, one about righteousness and commonship and one against diagnosis and network. The struggle for support and understanding from the surrounding network was central. There was also a fight between the network and the parent of the authority to decide the childâs normality. The parent and child early experience a segregation in society based on diagnose. Parents experienced insecurity and difficulties regarding dose and sideeffects in medication the child. The networks reception was central for the acceptance of diagnosis and for keeping the parentcompetence. The public debate of inherent or environment created doubt and insecurity. In the stories there was a tendency that the struggle went beside the child and parenthood and instead became a struggle for righteousness against society
Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter
Climate change and human pressures are changing the global distribution and the exâ
tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the
global river network area. IRES are characterized by periods of flow cessation, during
which channel substrates accumulate and undergo physicoâchemical changes (preconâ
ditioning), and periods of flow resumption, when these substrates are rewetted and
release pulses of dissolved nutrients and organic matter (OM). However, there are no
estimates of the amounts and quality of leached substances, nor is there information
on the underlying environmental constraints operating at the global scale. We experiâ
mentally simulated, under standard laboratory conditions, rewetting of leaves, riverâ
bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES
from five major climate zones. We determined the amounts and qualitative characterâ
istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds.
In addition, we evaluated the variance in leachate characteristics in relation to selected
environmental variables and substrate characteristics. We found that sediments, due
to their large quantities within riverbeds, contribute most to the overall flux of disâ
solved substances during rewetting events (56%â98%), and that flux rates distinctly
differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contribâ
uted most to the areal fluxes. The largest amounts of leached substances were found
in the continental climate zone, coinciding with the lowest potential bioavailability of
the leached OM. The opposite pattern was found in the arid zone. Environmental variâ
ables expected to be modified under climate change (i.e. potential evapotranspiration,
aridity, dry period duration, land use) were correlated with the amount of leached subâ
stances, with the strongest relationship found for sediments. These results show that
the role of IRES should be accounted for in global biogeochemical cycles, especially
because prevalence of IRES will increase due to increasing severity of drying event
First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data
International audienceWe report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100Â Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7ââ[1/Hz]. At the frequency of best strain sensitivity, near 100Â Hz, we set 90% confidence upper limits of 1.8Ă10-25. At the low end of our frequency range, 20Â Hz, we achieve upper limits of 3.9Ă10-24. At 55Â Hz we can exclude sources with ellipticities greater than 10-5 within 100Â pc of Earth with fiducial value of the principal moment of inertia of 1038ââkgâm2
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100ââMâ, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93ââGpcâ3âyrâ1 in comoving units at the 90%Â confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits