Impact of disturbance on common scoter carrying capacity based on an energetic model.

Shallow coastal zones are intensely used by humans but simultaneously are biodiversity hotspots, with a crucial role in the life cycle of many marine species. The competition for food or space between humans and protected wildlife intensifies under pressure of an increased need for marine resources for human consumption. For successful management it is important to establish the key components driving such conflicts of interest. Here we focus on the protected common scoter (Melanitta nigra), a sea duck wintering in coastal habitats that are rich in food, but also among the most disturbed marine systems worldwide. Due to the scoters' shyness disturbance impacts the birds' ability to forage and poses a conflict for balancing bird conservation and economics, including a fishery on its main bivalve prey Spisula subtruncata. In this study, we use an energy budget model to quantify the consequences of depth, currents and disturbance on scoter energetics and carrying capacity. Energetics were described using physical parameters and field data on food availability and disturbance. Results reveal non-linear relationships and a threshold value for when a scoter can no longer maintain its energy balance. This is caused by limited foraging time, rather than food availability. From a conservation perspective, this implies that a precautionary principle should be used, because there will be no warning when an area becomes unsuitable. In addition, the model was applied to study the effects of disturbance from different kinds of shipping in a coastal area of the North Sea, north of The Netherlands. Cargo shipping has the largest impact on the carrying capacity, where there is spatial overlap of prey and an intensively used shipping lane. In other prey distribution situations shrimp vessels may cause most disturbance. Spisula-Ensis fisheries did not limit the potential carrying capacity due to the limited catches and number of fishing trips. Scoter protection should be aimed at flexible spatial management and on only those vessel types above a Spisula bed with a large number of trips, and above all should work from a precautionary principle given the critical thresholds for scoter presence.

Quantum oscillations in an optically-illuminated two-dimensional electron system at the LaAlO3/SrTiO3interface.

We have investigated the illumination effect on the magnetotransport properties of a two-dimensional electron system at the LaAlO3/SrTiO3interface. The illumination significantly reduces the zero-field sheet resistance, eliminates the Kondo effect at low-temperature, and switches the negative magnetoresistance into the positive one. A large increase in the density of high-mobility carriers after illumination leads to quantum oscillations in the magnetoresistance originating from the Landau quantization. The carrier density (∼2 × 1012 cm-2) and effective mass (∼1.7me) estimated from the oscillations suggest that the high-mobility electrons occupy thedxz/yzsubbands of Ti:t2gorbital extending deep within the conducting sheet of SrTiO3. Our results demonstrate that the illumination which induces additional carriers at the interface can pave the way to control the Kondo-like scattering and study the quantum transport in the complex oxide heterostructures.

Phase interference for probing topological fractional charge in a BiSbTeSe2-based Josephson junction array.

Fractional charges can be induced by magnetic fluxes at the interface between a topological insulator (TI) and a type-II superconductor due to axion electrodynamics. In a Josephson junction array with a hole in the middle, these electronic states can have phase interference in an applied magnetic field with4×2πperiod, in addition to the 2πinterference of the Cooper pairs. Here, we test an experimental configuration for probing the fractional charge and report the observation of phase interference effect in superconducting arrays with a hole in the middle in both Au- and TI-based devices. Our numerical simulations based on resistive shunted capacitive junction model are in good agreement with the experimental results. However, no clear sign of an axion charge-related interference effect was observed. We will discuss possible reasons and perspectives for future experiments.

Gate-tuned anomalous Hall effect driven by Rashba splitting in intermixed LaAlO3/GdTiO3/SrTiO3.

The Anomalous Hall Effect (AHE) is an important quantity in determining the properties and understanding the behaviour of the two-dimensional electron system forming at the interface of SrTiO3-based oxide heterostructures. The occurrence of AHE is often interpreted as a signature of ferromagnetism, but it is becoming more and more clear that also paramagnets may contribute to AHE. We studied the influence of magnetic ions by measuring intermixed LaAlO3/GdTiO3/SrTiO3 at temperatures below 10 K. We find that, as function of gate voltage, the system undergoes a Lifshitz transition while at the same time an onset of AHE is observed. However, we do not observe clear signs of ferromagnetism. We argue the AHE to be due to the change in Rashba spin-orbit coupling at the Lifshitz transition and conclude that also paramagnetic moments which are easily polarizable at low temperatures and high magnetic fields lead to the presence of AHE, which needs to be taken into account when extracting carrier densities and mobilities.

Inhomogeneous superconductivity and quasilinear magnetoresistance at amorphous LaTiO3/SrTiO3 interfaces.

We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures. In spite of 2D growth observed in reflection high energy electron diffraction, transmission electron microscopy images revealed that the samples tend to amorphize. Still, we observe that the structures are conducting, and some of them exhibit high conductance and/or superconductivity. We established that conductivity arises mainly on the STO side of the interface, and shows all the signs of the two-dimensional electron gas usually observed at interfaces between STO and LTO or LaAlO3, including the presence of two electron bands and tunability with a gate voltage. Analysis of magnetoresistance (MR) and superconductivity indicates the presence of spatial fluctuations of the electronic properties in our samples. That can explain the observed quasilinear out-of-plane MR, as well as various features of the in-plane MR and the observed superconductivity.

Gate-Tunable Band Structure of the LaAlO_{3}-SrTiO_{3} Interface.

The two-dimensional electron system at the interface between LaAlO_{3} and SrTiO_{3} has several unique properties that can be tuned by an externally applied gate voltage. In this work, we show that this gate tunability extends to the effective band structure of the system. We combine a magnetotransport study on top-gated Hall bars with self-consistent Schrödinger-Poisson calculations and observe a Lifshitz transition at a density of 2.9×10^{13}cm^{-2}. Above the transition, the carrier density of one of the conducting bands decreases with increasing gate voltage. This surprising decrease is accurately reproduced in the calculations if electronic correlations are included. These results provide a clear, intuitive picture of the physics governing the electronic structure at complex-oxide interfaces.

Andreev Reflection in an s-Type Superconductor Proximized 3D Topological Insulator.

We investigate transport and shot noise in lateral normal-metal-3D topological-insulator-superconductor contacts, where the 3D topological insulator (TI) is based on Bi. In the normal state, the devices are in the elastic diffusive transport regime, as demonstrated by a nearly universal value of the shot noise Fano factor F_{N}≈1/3 in magnetic field and in a reference normal-metal contact. In the absence of magnetic field, we identify the Andreev reflection (AR) regime, which gives rise to the effective charge doubling in shot noise measurements. Surprisingly, the Fano factor F_{AR}≈0.22±0.02 is considerably reduced in the AR regime compared to F_{N}, in contrast to previous AR experiments in normal metals and semiconductors. We suggest that this effect is related to a finite thermal conduction of the proximized, superconducting TI owing to a residual density of states at low energies.

Observability of surface Andreev bound states in a topological insulator in proximity to an s-wave superconductor.

To guide experimental work on the search for Majorana zero-energy modes, we calculate the superconducting pairing symmetry of a three-dimensional topological insulator in combination with an s-wave superconductor. We show how the pairing symmetry changes across different topological regimes. We demonstrate that a dominant p-wave pairing relation is not sufficient to realise a Majorana zero-energy mode useful for quantum computation. Our main result is the relation between odd-frequency pairing and Majorana zero energy modes by using Green functions techniques in three-dimensional topological insulators in the so-called Majorana regime. We discuss thereafter how the pairing relations in the different regimes can be observed in the tunneling conductance of an s-wave proximised three-dimensional topological insulator. We discuss the necessity to incorporate a ferromagnetic insulator to localise the zero-energy bound state to the interface as a Majorana mode.

Minimal effects on ex vivo coagulation during mild therapeutic hypothermia in post cardiac arrest patients.

OBJECTIVES: Mild therapeutic hypothermia (MTH) is being used to improve neurological outcome and survival in patients successfully resuscitated after cardiac arrest. The impact on coagulation may be difficult to assess since most coagulation parameters are measured at 37°C and not at actual body core temperature. Therefore we investigated the effects of MTH both at body core (target) temperature of 32°C and at 37°C. METHODS: Patients admitted at the ICU after cardiac arrest treated with MTH. Baseline blood samples, measured at 37°C were taken directly at arrival. The second and third samples were drawn within 1h and 24h after reaching target temperature and were measured at 32°C and 37°C. A final sample was drawn when the patient returned to normotemperature (measured at 37°C). Clotting time (CT) and maximum clotting formation (MCF) were measured with thromboelastometry. RESULTS: Upon reaching target temperature (32°C) Extem and Intem CT were increased compared to baseline with 57s (49-75) to 65s (59-72) and 165s (144-183) to 193s (167-212) respectively (median with IQR; P<0.05), with a further significant increase after 24h of hypothermia with 68s (57-80) and 221s (196-266). Samples analyzed at 32°C showed a significant longer CT of 12s in Extem and 33s in Intem compared to 37°C. MCF was not affected by MTH or adjustment of temperature. CONCLUSION: The mild effect of MTH on coagulation parameters remains unidentified when measured at 37°C. Although measurements at 32°C differ from those at 37°C, this does not appear to be of clinical relevance as all values were still within the reference range.

Josephson supercurrent through a topological insulator surface state.

The long-sought yet elusive Majorana fermion is predicted to arise from a combination of a superconductor and a topological insulator. An essential step in the hunt for this emergent particle is the unequivocal observation of supercurrent in a topological phase. Here, direct evidence for Josephson supercurrents in superconductor (Nb)-topological insulator (Bi(2)Te(3))-superconductor electron-beam fabricated junctions is provided by the observation of clear Shapiro steps under microwave irradiation, and a Fraunhofer-type dependence of the critical current on magnetic field. Shubnikov-de Haas oscillations in magnetic fields up to 30 T reveal a topologically non-trivial two-dimensional surface state. This surface state is attributed to mediate the ballistic Josephson current despite the fact that the normal state transport is dominated by diffusive bulk conductivity. The lateral Nb-Bi(2)Te(3)-Nb junctions hence provide prospects for the realization of devices supporting Majorana fermions.

Upper limit to magnetism in LaAlO3/SrTiO3 heterostructures.

Using polarized neutron reflectometry we measured the neutron spin-dependent reflectivity from four LaAlO(3)/SrTiO(3) superlattices. Our results imply that the upper limit for the magnetization averaged over the lateral dimensions of the sample induced by an 11 T magnetic field at 1.7 K is less than 2 G. SQUID magnetometry of the neutron superlattice samples sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO(3) and SrTiO(3).

Conductance anisotropy and linear magnetoresistance in La(2 - x)Sr(x)CuO4 thin films.

We have performed a detailed study of conductance anisotropy and magnetoresistance (MR) of La(2 - x)Sr(x)CuO(4) (LSCO) thin films (0.10 < x < 0.25). These two observables are promising for the detection of stripes. Subtle features of the conductance anisotropy are revealed by measuring the transverse resistance R(xy) in zero magnetic field. It is demonstrated that the sign of R(xy) depends on the orientation of the LSCO Hall bar with respect to the terrace structure of the substrate. Unit-cell-high substrate step edges must therefore be a dominant nucleation source for antiphase boundaries during film growth. We show that the measurement of R(xy) is sensitive enough to detect the cubic-tetragonal phase transition of the SrTiO(3)(100) (STO) substrate at 105 K. The MR of LSCO thin films shows for 0.10 < x < 0.25 a non-monotonic temperature dependence, resulting from the onset of a linear term in the MR above 90 K. We show that the linear MR scales with the Hall resistivity as [Formula: see text], with the constant of proportionality independent of temperature. Such scaling suggests that the linear MR originates from current distortions induced by structural or electronic inhomogeneities. The possible role of stripes for both the MR and the conductance anisotropy is discussed throughout the paper.

Nonlocal Cooper pair splitting in a pSn junction.

Perfect Cooper pair splitting is proposed, based on crossed Andreev reflection (CAR) in a p-type semiconductor-superconductor-n-type semiconductor (pSn) junction. The ideal splitting is caused by the energy filtering that is enforced by the band structure of the electrodes. The pSn junction is modeled by the Bogoliubov-de Gennes equations and an extension of the Blonder-Tinkham-Klapwijk theory beyond the Andreev approximation. Despite a large momentum mismatch, the CAR current is predicted to be large. The proposed straightforward experimental design and the 100% degree of pureness of the nonlocal current open the way to pSn structures as high quality sources of entanglement.

Parallel electron-hole bilayer conductivity from electronic interface reconstruction.

The perovskite SrTiO3-LaAlO3 structure has advanced to a model system to investigate the rich electronic phenomena arising at polar oxide interfaces. Using first principles calculations and transport measurements we demonstrate that an additional SrTiO3 capping layer prevents atomic reconstruction at the LaAlO3 surface and triggers the electronic reconstruction at a significantly lower LaAlO3 film thickness than for the uncapped systems. Combined theoretical and experimental evidence (from magnetotransport and ultraviolet photoelectron spectroscopy) suggests two spatially separated sheets with electron and hole carriers, that are as close as 1 nm.

CITED2 and NCOR2 in anti-oestrogen resistance and progression of breast cancer.

BACKGROUND: Endocrine therapies of breast cancer are effective but ultimately fail because of the development of treatment resistance. We have previously revealed several genes leading to tamoxifen resistance in vitro by retroviral insertion mutagenesis. To understand the manner in which these genes yield tamoxifen resistance, their effects on global gene expression were studied and those genes resulting in a distinct gene expression profile were further investigated for their clinical relevance. METHODS: Gene expression profiles of 69 human breast cancer cell lines that were made tamoxifen resistant through retroviral insertion mutagenesis were obtained using oligonucleotide arrays and analysed with bioinformatic tools. mRNA levels of NCOR2 and CITED2 in oestrogen receptor-positive breast tumours were determined by quantitative RT-PCR. mRNA levels were evaluated for association with metastasis-free survival (MFS) in 620 patients with lymph node-negative primary breast cancer who did not receive systemic adjuvant therapy, and with clinical benefit in 296 patients receiving tamoxifen therapy for recurrent breast cancer. RESULTS: mRNA expression profiles of most tamoxifen-resistant cell lines were strikingly similar, except for the subgroups of cell lines in which NCOR2 or CITED2 were targeted by the retrovirus. Both NCOR2 and CITED2 mRNA levels were associated with MFS, that is, tumour aggressiveness, independently of traditional prognostic factors. In addition, high CITED2 mRNA levels were predictive for a clinical benefit from first-line tamoxifen treatment in patients with advanced disease. CONCLUSIONS: Most retrovirally targeted genes yielding tamoxifen resistance in our cell lines do not impose a distinctive expression profile, suggesting that their causative role in cell growth may be accomplished by post-transcriptional processes. The associations of NCOR2 and CITED2 with outcome in oestrogen receptor-positive breast cancer patients underscore the clinical relevance of functional genetic screens to better understand disease progression, which may ultimately lead to the development of improved treatment options.

Andreev spectra and subgap bound states in multiband superconductors.

A theory of Andreev conductance is formulated for junctions involving normal metals (N) and multiband superconductors (S) and applied to the case of superconductors with nodeless extended s(+/-)-wave order parameter symmetry, as possibly realized in the recently discovered ferropnictides. We find qualitative differences from tunneling into s-wave or d-wave superconductors that may help to identify such a state. First, interband interference leads to a suppression of Andreev reflection in the case of a highly transparent N/S interface and to a current deficit in the tunneling regime. Second, surface bound states may appear, both at zero and at nonzero energies.

Prehospital endotracheal intubation in patients with severe traumatic brain injury: guidelines versus reality.

The international Brain Trauma Foundation guidelines recommend prehospital endotracheal intubation in all patients with traumatic brain injury (TBI) and a Glasgow Coma Scale (GCS)< or =8. Close adherence to these guidelines is associated with improved outcome, but not all severely injured TBI patients receive adequate prehospital airway support. Here we hypothesized that guideline adherence varies when skills are involved that rely on training and expertise, such as endotracheal intubation. We retrospectively studied the medical records of CT-confirmed TBI patients with a GCS< or =8 who were referred to a level 1 trauma centre in Amsterdam (n=127). Records were analyzed for demographic parameters, prehospital treatment modalities, involvement of an emergency medical service (EMS) and respiratory and metabolic parameters upon arrival at the hospital. Patients were mostly male, aged 45+/-21 years with a median injury severity score (ISS) of 26. Of all patients for whom guidelines recommend endotracheal intubation, only 56% were intubated. In 21 out of 106 severe cases an EMS was not called for, suggesting low guideline adherence. Especially those TBI patients treated by paramedics tended to develop higher levels of stress markers like glucose and lactate. We observed a low degree of adherence to intubation guidelines in a Dutch urban area. Main reasons for low adherence were the unavailability of specialized care, scoop and run strategies and absence of a specialist physician in cases where intubation was recommended. The discrepancy between guidelines and reality warrants changing practice to improve guideline compliance and optimize outcome in TBI patients.

Orbital reconstruction and the two-dimensional electron gas at the LaAlO3/SrTiO3 interface.

In 2004, Ohtomo and Hwang discovered that an electron gas is created at the interface between insulating LaAlO3 and SrTiO3 compounds. Here we show that the generation of a conducting electron gas is related to an orbital reconstruction occurring at the LaAlO3/SrTiO3 interface. Our results are based on extensive investigations of the electronic properties and of the orbital structure of the interface using x-ray absorption spectroscopy. In particular, we find that the degeneracy of the Ti 3d states is fully removed and that the Ti 3d xy levels become the first available states for conducting electrons.

High-T(c) superconducting thin films with composition control on a sub-unit cell level; the effect of the polar nature of the cuprates.

Inspired by the work of Ohtomo and Hwang in 2004, we shed new light on thin films of layered cuprate high-T(c) superconductors (HTS). In principle all HTS materials consist of charged perovskite-like layers which in thin films can lead to polar discontinuities at the interfaces of different materials. The resulting charge redistribution has to occur but we expect it to be far more complex than in the LaAlO(3)/SrTiO(3) system since copper can be multivalent. This makes it hard to predict what will happen in terms of transport or even magnetic properties compared to the 'simple' insulator LaAlO(3). Nevertheless, we point out that the picture of systems of charged layers is important and necessary to fully understand heterostructures of these complex materials.