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Papers by Peter Klint K Jensen

Biological Psychiatry, 2015

An adverse response to acute and pronounced changes in sex-hormone levels during, for example, th... more An adverse response to acute and pronounced changes in sex-hormone levels during, for example, the perimenopausal or postpartum period appears to heighten risk for major depression in women. The underlying risk mechanisms remain elusive but may include transiently compromised serotonergic brain signaling. Here, we modeled a biphasic ovarian sex hormone fluctuation using a gonadotropin-releasing hormone agonist (GnRHa) and evaluated if emergence of depressive symptoms was associated with change in cerebral serotonin transporter (SERT) binding following intervention. A double-blind, randomized, placebo-controlled study included 63 healthy female volunteers (mean age 24.3 ± 4.9 years) with regular menstrual cycles between 23 and 35 days. Participants were randomized to active (goserelin [GnRHa] 3.6 mg implant) or placebo intervention. Sixty women completed follow-up and entered the analyses. Primary outcome measures were changes from baseline in depressive symptoms assessed on the 17-item Hamilton Depression Rating Scale and SERT binding as imaged by [(11)C]DASB positron emission tomography. Outcome measures were acquired at baseline in the follicular phase (cycle day 6.6 ± 2.2) and at follow-up (16.2 ± 2.6 days after intervention start). Sex hormone manipulation with GnRHa significantly triggered subclinical depressive symptoms within-group (p = .003) and relative to placebo (p = .02), which were positively associated with net decreases in estradiol levels (p = .02) from baseline within the GnRHa group. Depressive symptoms were associated with increases in neocortical SERT binding in the GnRHa group relative to placebo (p = .003). Our data imply both serotonergic signaling and estradiol in the mechanisms by which sex-steroid hormone fluctuations provoke depressive symptoms and thus provide a rationale for future preventive strategies in high-risk groups.

Canadian Journal of …, 2011

Many workers continue to model Nares Strait between Greenland and Ellesmere Island, Canada, as a ... more Many workers continue to model Nares Strait between Greenland and Ellesmere Island, Canada, as a plate boundary and locus of major Cenozoic compression and strike-slip, marked by the postulated Wegener (transform) Fault. This, despite continuity of Precambrian–Paleozoic provinces across the seaway including an undeformed Neoproterozoic mafic dyke swarm that crosses at a high angle. As a test of the speculative plate kinematic modelling, apatite fission track (AFT) dating was undertaken along a transect across the ...

Atmospheric Environment, 1995

Reactive below-cloud scavenging is simulated using general chemical reaction simulation. Modellin... more Reactive below-cloud scavenging is simulated using general chemical reaction simulation. Modelling of mass transfer is mathematically equivalent to modelling of chemical reactions. The computer mode1 is flexible as regards input of chemical reactions and transport of species, which means that changes in the components, reactions, and transport of species can be made without reprogramming. The numbers of species, reactions, and compartments between which mass transfer takes place may be large and they are only limited by computing time and memory capacity. The set-up of the matrix equation necessary for general simulation of chemical reactions and transport of species is applied for scavenging of a NH, plume.

Computerized Basin …, 1993

Abstract Forward modeling of fission track annealing of apatites is used together with basin mode... more Abstract Forward modeling of fission track annealing of apatites is used together with basin modeling to estimate past heat flow and amount of erosion. For a known uranium concentration the track length histogram and the surface track density, hold information on the thermal history of the minerals. An equation is developed which is used to determine the number of horizontal (relative to prismatic faces) tracks in the histogram that has been generated after deposition. The post-sedimentary thermal history of the sample is ...

International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 1992

A numerical model for determination of the thermal history of rocks is presented. It is shown tha... more A numerical model for determination of the thermal history of rocks is presented. It is shown that the thermal history may be uniquely determined as a piece-by-piece linear function on the basis of etched confined, horizontal fission track length distributions, their surface densities, and the uranium content. The initial track length distribution is taken into account. A relation between the measured track length distribution and age is given which includes correlation for partial annealing. The annealing model used is the fanning Arrhenius plot. It is shown that track length distributions measured in transmitted light are biased favouring short tracks compared with measurements in reflected light. Testing of the model is performed on apatites from a tuffaceous sandstone from Bornholm (Denmark) yielding an estimate of the thermal history for the period of about 280 Ma back in time.

Abstract The temperature field around salt diapirs has been calculated with a finite-element meth... more Abstract The temperature field around salt diapirs has been calculated with a finite-element method, whose accuracy is estimated by comparing simulation results with analytical solutions. Temperature, anomaly, and heat flux are calculated in cross-sections through two-dimensional (2D) and axisymmetric (3D) structures. The anomalous temperature field extends to a lateral distance of about 3 diapir radii from the diapir center. At depth the anomaly disappears at about 2.5 times the depth to the base of the diapir.

Geophysical Transactions, 1997

… in Exploration of the Norwegian Shelf, 1986

Abstract A model that simulates burial history, temperature and maturation is described. The subs... more Abstract A model that simulates burial history, temperature and maturation is described. The subsidence of a surface layer, including compaction, is determined as a function of time by an analytical expression. Compaction of underlying layers and erosion are also considered. Formation temperatures are calculated analytically, with conductivity being a function of porosity. Maturity modelling is based on an empirical expression relating vitrinite reflectance, temperature and time.

Geophysical Prospecting, 1983

Temperature modeling around the Vejrum salt structure in Denmark shows that the heat flow near th... more Temperature modeling around the Vejrum salt structure in Denmark shows that the heat flow near the top is twice the regional heat flow. The temperature in the vicinity of the top of the diapir is thus anomalously high. Overlying permeable formations could therefore be attractive for geothermal energy exploitation. A negative temperature anomaly of −20°C is calculated around the root of the salt body. Comparisons between calculated and measured temperatures are used to test the model. It is shown that measurements of heat flow (or temperature gradients) in wells penetrating the region of groundwater circulation could be used in identification of salt diapirs.

Tectonophysics, 1988

Granitic intrusions older than 1200 Ma, from an area west of lake Vänern, south Sweden, show fiss... more Granitic intrusions older than 1200 Ma, from an area west of lake Vänern, south Sweden, show fission track ages of 680 ± 50 Ma (2 σ) (Late Precambrian) for sphene and 220 ± 10 Ma (Late Triassic) for apatite. The samples were taken at the present post-glacial erosion surface which is close to the sub-Cambrian peneplain. The c. 680 Ma sphene fission track ages are thought to be related to the uplift of the area which led to the establishment of this erosion surface at c. 600 Ma ago. The much younger apatite fission track ages and the confined spontaneous track length distributions along with regional stratigraphic constraints suggest that the basement was subsequently buried under 3–4 km of Paleozoic supracrustals. This induced in the basement a rise in temperature which obliterated the older apatite fission tracks, but not those in sphene which has a higher closure temperature. At the beginning of the Mesozoic, the area was uplifted again, the cover rocks were removed, and the basement rocks cooled slowly below the temperature range of fission track annealing in apatite.

Abstract Methods, parameterisations and models have been developed, which give insight in process... more Abstract Methods, parameterisations and models have been developed, which give insight in processes that are important for deposition of nitrogen compounds to the sea. This knowledge has been applied to the Kattegat Strait for which a nitrogen deposition of 960 kg N km-2 yr-1 was calculated with an atmospheric transport model.