Magnetoconductance Anisotropies and Aharonov-Casher Phases.

The spin-orbit interaction (SOI) is a key tool for manipulating and functionalizing spin-dependent electron transport. The desired function often depends on the SOI-generated phase that is accumulated by the wave function of an electron as it passes through the device. This phase, known as the Aharonov-Casher phase, therefore depends on both the device geometry and the SOI strength. Here, we propose a method for directly measuring the Aharonov-Casher phase generated in an SOI-active weak link, based on the Aharonov-Casher-phase dependent anisotropy of its magnetoconductance. Specifically, we consider weak links in which the Rashba interaction is caused by an external electric field, but our method is expected to apply also for other forms of the spin-orbit coupling. Measuring this magnetoconductance anisotropy thus allows calibrating Rashba spintronic devices by an external electric field that tunes the spin-orbit interaction and hence the Aharonov-Casher phase.

Epidemiology of suicidal feelings in an ageing Swedish population: from old to very old age in the Gothenburg H70 Birth Cohort Studies.

AIMS: The first aim of this study was to provide prevalence suicidal feelings over time (past week, past month, past year and lifetime) in a population-based sample of old to very old adults without dementia. Does prevalence change with rising age? The second aim was to examine the fluctuation of suicidal feelings over time. How does this coincide with depression status? METHODS: Data were derived from the Gothenburg H70 Birth Cohort Studies (the H70 studies) which are multidisciplinary longitudinal studies on ageing. A representative sample of adults in Gothenburg, Sweden with birth years 1901-1944 were invited to take part in a longitudinal health study on ageing and participated at one or more occasions during 1986-2014. The sample consisted of 6668 observations originating from 3972 participants without dementia between the ages of 70 and 108, including 1604 participants with multiple examination times. Suicidal feelings were examined during a psychiatric interview using the Paykel questions (life not worth living, death wishes, thoughts of taking own life, seriously considered taking life, attempted suicide). RESULTS: Prevalence figures for suicidal feelings of any severity were as follows: past week 4.8%, past month 6.7%, past year 11.2% and lifetime 25.2%. Prevalence rates increased with age in the total group and in women but not in men. Suicidal feelings were common in participants with concurrent major or minor depression, but over a third of the participants who reported suicidal feelings did not fulfil criteria for these diagnoses nor did they present elevated mean depressive symptom scores. The majority of participants consistently reported no experience of suicidal feelings over multiple examination times, but fluctuation was more common in women compared with men. CONCLUSION: Suicidal feelings in late-life are uncommon in individuals without depression indicating that such behaviour is not a widespread, normative phenomenon. However, such feelings may occur outside the context of depression.

Spin-mediated Photomechanical Coupling of a Nanoelectromechanical Shuttle.

We show that nanomechanical vibrations in a magnetic shuttle device can be strongly affected by external microwave irradiation through photo-assisted electronic spin-flip transitions. Mechanical consequences of these spin flips are due to a spin-dependent magnetic force, which may lead to a nanomechanical instability in the device. We derive a criterion for the instability to occur and analyze different regimes of nanomechanical oscillations. Possible experimental realizations of the spin-mediated photomechanical instability and detection of the device backaction are discussed.

Rashba Splitting of Cooper Pairs.

We investigate theoretically the properties of a weak link between two superconducting leads, which has the form of a nonsuperconducting nanowire with a strong Rashba spin-orbit coupling caused by an electric field. In the Coulomb-blockade regime of single-electron tunneling, we find that such a weak link acts as a "spin splitter" of the spin states of Cooper pairs tunneling through the link, to an extent that depends on the direction of the electric field. We show that the Josephson current is sensitive to interference between the resulting two transmission channels, one where the spins of both members of a Cooper pair are preserved and one where they are both flipped. As a result, the current is a periodic function of the strength of the spin-orbit interaction and of the bending angle of the nanowire (when mechanically bent); an identical effect appears due to strain-induced spin-orbit coupling. In contrast, no spin-orbit induced interference effect can influence the current through a single weak link connecting two normal metals.

Single-electron shuttle based on electron spin.

A nanoelectromechanical device based on magnetic exchange forces and electron spin flips induced by a weak external magnetic field is suggested. It is shown that this device can operate as a new type of single-electron "shuttle" in the Coulomb blockade regime of electron transport.

Spin-controlled nanomechanics induced by single-electron tunneling.

We consider dc-electronic transport through a nanowire suspended between normal- and spin-polarized metal leads in the presence of an external magnetic field. We show that magnetomotive coupling between the electrical current through the nanowire and vibrations of the wire may result in self-excitation of mechanical vibrations. The self-excitation mechanism is based on correlations between the occupancy of the quantized electronic energy levels inside the nanowire and the velocity of the nanowire. We derive conditions for the occurrence of the instability and find stable regimes of mechanical oscillations.

Self-reported attachment style, trauma exposure and dissociative symptoms among adolescents.

The aim of this study was to analyze whether self-reported attachment style (measuring avoidance and anxiety) among adolescents was associated with dissociative symptoms, in addition to self-reported potentially traumatic experiences. A group consisting of 462 adolescents completed three self-assessment questionnaires: Linkoping Youth Life Experience Scale (LYLES), Experiences in Close Relationships, modified version (ECR) and Dissociation Questionnaire Sweden (Dis-Q-Sweden). Self-reported attachment style had a stronger association with dissociative symptoms than self reported traumas. It was also found that scores on a dissociation questionnaire correlated strongly with scores on self-reported attachment style in adolescence. Discussion concerns reasons why self-reported attachment style is an important factor that may influence dissociative symptoms during adolescence.

Cooling of nanomechanical resonators by thermally activated single-electron transport.

We show that the vibrations of a nanomechanical resonator can be cooled to near its quantum ground state by tunneling injection of electrons from a scanning tunneling microscope tip. The interplay between two mechanisms for coupling the electronic and mechanical degrees of freedom results in a bias-voltage-dependent difference between the probability amplitudes for vibron emission and absorption during tunneling. For a bias voltage just below the Coulomb blockade threshold, we find that absorption dominates, which leads to cooling corresponding to an average vibron population of the fundamental bending mode of 0.2.

Differential effects of polymers PVP90 and Ficoll400 on storage stability and viability of Lactobacillus coryniformis Si3 freeze-dried in sucrose.

AIMS: To investigate the effect of freeze-dried Lactobacillus coryniformis Si3 on storage stability by adding polymers to sucrose-based formulations and to examine the relationship between amorphous matrix stability and cell viability. METHODS AND RESULTS: The resistance to moisture-induced sucrose crystallization and effects on the glass transition temperature (Tg) by the addition of polymers to the formulation were determined by different calorimetric techniques. Both polymers increased the amorphous matrix stability compared to the control, and poly(vinyl)pyrrolidone K90 was more effective in increasing amorphous stability than Ficoll 400. The viability of Lact. coryniformis Si3 after storage was investigated by plate counts following exposure to different moisture levels and temperatures for up to 3 months. The polymers enhanced the cellular viability to different degrees, dependent upon polymer and storage condition. CONCLUSIONS: Polymers can be used to enhance the stability of freeze-dried Lact. coryniformis Si3 products, but cell viability and matrix stability do not always correlate. The general rule of thumb to keep a highly amorphous product 50 degrees below its Tg for overall stability seemed to apply for this type of bacterial products. We showed that by combining thermal analysis with plate counts, it was possible to determine storage conditions where cell viability and matrix stability were kept high. SIGNIFICANCE AND IMPACT OF THE STUDY: The results will aid in the rational formulation design and proper determination of storage conditions for freeze-dried and highly amorphous lactic acid bacteria formulations. We propose a hypothesis of reason for different stabilizing effects on the cells by the different polymers based on our findings and previous findings.

Self-organization of irregular nanoelectromechanical vibrations in multimode shuttle structures.

We investigate theoretically multimode electromechanical "shuttle" instabilities in dc voltage-biased nanoelectromechanical single-electron tunneling devices. We show that initially irregular (quasiperiodic) oscillations that occur as a result of the simultaneous self-excitation of several mechanical modes with incommensurable frequencies self-organize into periodic oscillations with a frequency corresponding to the eigenfrequency of one of the unstable modes. This effect demonstrates that a local probe can selectively excite global vibrations of extended objects.

Electronic Aharonov-Bohm effect induced by quantum vibrations.

Mechanical displacements of a nanoelectromechanical system shift the electron trajectories and hence perturb phase coherent charge transport through the device. We show theoretically that in the presence of a magnetic field such quantum-coherent displacements may give rise to an Aharonov-Bohm-type of effect. In particular, we demonstrate that quantum vibrations of a suspended carbon nanotube result in a positive nanotube magnetoresistance, which decreases slowly with the increase of temperature. This effect may enable one to detect quantum displacement fluctuations of a nanomechanical device.

Factores asociados al pronóstico de los pacientes pediátricos ventilados mecánicamente. Un estudio internacional / Factors associated with the prognosis of mechanically ventilated infants and children. An international study

Objetivo. Identificar los factores asociados con la supervivencia de los pacientes pediátricos que reciben, durante el ingreso en la Unidad de Cuidados Intensivos Pediátricos (UCIP), asistencia ventilatoria mecánica (AVM) por un tiempo superior a 12 horas. Diseño. Estudio prospectivo de cohorte, realizado entre el 1 de abril y el 31 de mayo de 1999 y con seguimiento de los pacientes durante 28 días o hasta el alta de UCIP si ocurría antes. Ámbito. Treinta y seis UCIP de 7 países. Pacientes. Se incluyeron en el estudio 659 pacientes ventilados y 15 fueron excluidos del análisis por desconocer su estado vital al alta. Resultados. La mortalidad al alta de la UCIP fue de 15,6%. Mediante particiones recursivas y regresión logística se construyó un árbol de decisión en relación con la supervivencia. Las variables asociadas a mortalidad fueron: presión inspiratoria pico (PIP), fallo renal agudo (FRA), puntuación en el score PRISM , PaO2/FiO2 100 y PRISM 27 incrementaban la mortalidad a 26% (OR: 4,4; IC 95 % 2-9,4) y a 43% (OR: 9,6; IC 95 % 4,2-25,8) respectivamente. El desarrollo de FRA la incrementaba al 50% (OR: 12,7; IC 95 % 6,3-25,7) y el uso de PIP * 35 cmH2O al 58% (OR 17,3; IC 95 % 8,5-36,3). Conclusión. En una gran cohorte de pacientes pediátricos ventilados mecánicamente, encontramos que la gravedad de la enfermedad al ingreso en la UCIP, un alto valor de PIP, el desarrollo de FRA e hipoxemia severa están asociadas con una menor supervivencia

Objetive. Identify factors associated with the survival of pediatric patients who are submitted to mechanical ventilation (MV) for more than 12 hours. Design. International prospective cohort study. It was performed between April 1 and May 31 1999. All patients were followed-up during 28 days or discharge to pediatric intensive care unit (PICU). Setting. 36 PICUs from 7 countries. Patients. A total of 659 ventilated patients were enrolled but 15 patients were excluded because their vital status was unknown on discharge. Results. Overall in-UCIP mortality rate was 15,6%. Recursive partitioning and logistic regression were used and an outcome model was constructed. The variables significantly associated with mortality were: peak inspiratory pressure (PIP), acute renal failure (ARF), PRISM score and severe hypoxemia (PaO2/FiO2 100 and PRISM 27 on admission to PICU had a mortality of 43% (OR: 9.6; 95% CI 4,2 to 25,8). Development of acute renal failure was associated with a mortality of 50% (OR: 12.7; 95% CI 6.3 to 25.7). Finally, the worst outcome (mortality 58%) was for patients with a mean PIP * 35 cmH2O (OR 17.3; 95% CI 8.5 to 36.3). Conclusion. In a large cohort of mechanically ventilated pediatric patients we found that severity of illness at admission, high mean PIP, development of acute renal failure and severe hypoxemia over the course of MV were the factors associated with lower survival rate

Coulomb promotion of spin-dependent tunneling.

We study transport of spin-polarized electrons through a magnetic single-electron transistor (SET) in the presence of an external magnetic field. Assuming the SET to have a nanometer size central island with a single-electron level we find that the interplay on the island between coherent spin-flip dynamics and Coulomb interactions can make the Coulomb correlations promote rather than suppress the current through the device. We find the criteria for this new phenomenon--Coulomb promotion of spin-dependent tunneling--to occur.

Spintronics of a nanoelectromechanical shuttle.

We consider effects of the spin degree of freedom on the nanomechanics of a single-electron transistor (SET) containing a nanometer-sized metallic cluster suspended between two magnetic leads. It is shown that in such a nanoelectromechanical SET (NEM-SET) the onset of an electromechanical instability leading to cluster vibrations and shuttle transport of electrons between the leads can be controlled by an external magnetic field. Different stable regimes of this spintronic NEM-SET operation are analyzed. Two different scenarios for the onset of shuttle vibrations are found.

Electronic transduction in model enzyme sensors assisted by a photoisomerizable azo-polymer.

We develop a stochastic model of electronic transduction by means of a rod-like azo-polymer (single peptide molecule doped with a given amount of azo-benzene structural units) in polymer-redox enzyme biosensor. We propose a configuration where the azo-polymer is anchored next to the enzyme reaction center and functions as a light-driven micromechanical actuator shuttling electrons toward the electrode. We show that the output catalytic current is exponentially sensitive to variations in geometrical size of the polymer (a 'switch off' effect) and suggest a scheme where the switching effect is triggered by polymer photoisomerization, resulting in its overall length change.

Quantum shuttle phenomena in a nanoelectromechanical single-electron transistor.

An analytical analysis of quantum shuttle phenomena in a nanoelectromechanical single-electron transistor has been performed in the realistic case, when the electron tunneling length is much greater than the amplitude of the zero point oscillations of the central island. It is shown that when the dissipation is below a certain threshold value, the vibrational ground state of the central island is unstable. The steady state into which this instability develops is studied. It is found that if the electric field E between the leads is much greater than a characteristic value E(q), the quasiclassical shuttle picture is recovered, while if E<0) shuttle vibrations.

Electrical manipulation of nanomagnets.

We demonstrate that it is possible to manipulate the magnetic coupling between two nanomagnets by means of an ac electric field. In the scheme suggested, the magnetic coupling is mediated by a magnetic particle that is in contact with both nanomagnets via tunnel barriers. The time-dependent electric field is applied so that the height of first one barrier then the other is suppressed in an alternating fashion. We show that the result is a pumping of magnetization from one nanomagnet to the other through the mediating particle. The dynamics of the magnetization of the mediating particle allows the coupling to be switched between being ferromagnetic and being antiferromagnetic.

Missing mass effect in biosensor's QCM applications.

Nowadays, liquid applications of quartz crystal microbalance (QCM) opened a way for in situ studies of proteins, vesicles and cells adsorbed from the solution onto the QCM surface. The sensitivity of QCM to the viscoelasticity of the adsorbed biomaterial can be a reason of the experimentally observed deviation from a linear dependence of QCM resonant frequency on mass deposition (the so-called Sauerbrey relation) and can limit its application for biosensoring. Presented here rigorous theoretical analysis explains the deviation from ideal mass response of soft overlayers in the contact with liquid. The fundamental result of the theory is the analog of Sauerbrey relation for layered viscous/viscoelastic medium which can be exploited for the correct physical interpretation of QCM experimental data in biofluids, in particular for measurements of the 'true' surface mass of adsorbed biomolecular films. We predict a new physical effect 'missing mass' of the sample in liquid phase measurements and compare the results given by our theory with QCM measurements on supported membranes.

Mechanical Cooper pair transportation as a source of long-distance superconducting phase coherence.

Transportation of Cooper pairs by a movable single Cooper-pair box placed between two remote superconductors is shown to establish coherent coupling between them. This coupling is due to entanglement of the movable box with the leads and is manifested in the suppression of quantum fluctuations of the relative phase of the order parameters of the leads. It can be probed by attaching a high resistance Josephson junction between the leads and measuring the current through this junction. The current is suppressed with increasing temperature.

Coherent transfer of Cooper pairs by a movable grain.

Superconducting circuits that incorporate Josephson junctions are of considerable experimental and theoretical interest, particularly in the context of quantum computing. A nanometre-sized superconducting grain (commonly referred to as a Cooper-pair box) connected to a reservoir by a Josephson junction is an important example of such a system. Although the grain contains a large number of electrons, it has been experimentally demonstrated that its states are given by a superposition of only two charge states (differing by 2e, where e is the electronic charge). Coupling between charge transfer and mechanical motion in nanometre-sized structures has also received considerable attention. Here we demonstrate theoretically that a movable Cooper-pair box oscillating periodically between two remote superconducting electrodes can serve as a mediator of Josephson coupling, leading to coherent transfer of Cooper pairs between the electrodes. Both the magnitude and the direction of the resulting Josephson current can be controlled by externally applied electrostatic fields.