De zin van het economische opnieuw beschouwd

In 1950 heb ik het hoogleraarschap in de economie aan de juridische faculteit der Vrije Universiteit te Amsterdam aanvaard m et een rede over de zin van het economische. Sinds- dien heeft dit centiaal m elhodologisch vraagstuk van de we- tenschap der economie mij ook verder bezig gehouden. Het is voor een economist een m oeilijk vraagstuk, om dat het tevens een wijsgerig vraagstuk is. Over het algemeen vindt de econo­ m ist daarover weinig in de filosofische liLeratuur. Dit is zeer begrijpelijk, w ant wijsgeren kunnen op zijn best m aar heel sum m ier kennis nem en van wat er in de vakw etenschappen omgaat, terw ijl zij, voor zover mij bekend, in den regel slechts weinig belangstelling voor de economie aan den dag leggen. Omgekeerd zijn econom islen m eestal niet bijzonder filosofisch aangelegd, en hebben zij de handen vol om de storm achtige ontwikkeling van liun eigen literatuur enigzins bij te houden afgezien nog van het l'eit dat zij in den regel vele praktischc beslom m eringen hebben, ten gevolge waarvan zij zich niet ongestoord aan de studie kunnen wijden. Van een behoorlijk sam enspel tussen filosolen en economislen komt over het ge- heel ook niet veel terecht. Wat de wijsgerige kant van m ijn overpeizingen betreft, ben ik dus door de nood gedwongen slechts am ateur. Ik kom daar gaarne voor uit, en ik ben steeds bereid te zwichten voor het beter oordeel der wijsgeren, m its ik dat kan vatten, en in m ijn eigen w erk daar iets mee uit kan richten. Men behoeft nog geen door de wol geverfd prag­ m atist of operationalist te zijn om te weten dat ieder werk zijn eigen eisen stelt

Magnetoresistance, Micromagnetism and Domain Wall Effects in Epitaxial Fe and Co Structures with Stripe Domains

We review our recent magnetotransport and micromagnetic studies of lithographically defined epitaxial thin film structures of bcc Fe and hcp Co with stripe domains. Micromagnetic structure and resistivity anisotropy are shown to be the predominant sources of low field magnetoresistance (MR) in these microstructures, with domain wall (DW) effects smaller but observable (DW-MR $\lesssim 1$). In Fe, at low temperature, in a regime in which fields have a significant effect on electron trajectories, a novel negative DW contribution to the resistivity is observed. In hcp Co microstructures, temperature dependent transport measurements for current perpendicular and parallel to walls show that any additional resistivity due to DW scattering is very small.Comment: 7 pages, 8 figures, to appear in Journal of Applied Physics 199

Self-tracking of physical activity in people with type 2 diabetes:a randomized controlled trial

The purpose of this study was to determine the efficacy of an online self-tracking program on physical activity, glycated hemoglobin, and other health measures in patients with type 2 diabetes. Seventy-two patients with type 2 diabetes were randomly assigned to an intervention or control group. All participants received usual care. The intervention group received an activity tracker (Fitbit Zip) connected to an online lifestyle program. Physical activity was analyzed in average steps per day from week 0 until 12. Health outcome measurements occurred in both groups at baseline and after 13 weeks. Results indicated that the intervention group significantly increased physical activity with 1.5 +/- 3 days per week of engagement in 30 minutes of moderate-vigorous physical activity versus no increase in the control group (P = .047). Intervention participants increased activity with 1255 +/- 1500 steps per day compared to their baseline (P <.010). No significant differences were found in glycated hemoglobin A1c, with the intervention group decreasing -0.28% +/- 1.03% and the control group showing -0.0% +/- 0.69% (P = .206). Responders (56%, increasing minimally 1000 steps/d) had significantly decreased glycated hemoglobin compared with nonresponders (-0.69% +/- 1.18% vs 0.22% +/- 0.47%, respectively; P = .007). To improve effectiveness of eHealth programs, additional strategies are needed

Very large dielectric response of thin ferroelectric films with the dead layers

We study the dielectric response of ferroelectric (FE) thin films with "dead" dielectric layer at the interface with electrodes. The domain structure inevitably forms in the FE film in presence of the dead layer. As a result, the effective dielectric constant of the capacitor $\epsilon_{eff}$ increases abruptly when the dead layer is thin and, consequently, the pattern of 180-degree domains becomes "soft". We compare the exact results for this problem with the description in terms of a popular "capacitor" model, which is shown to give qualitatively incorrect results. We relate the present results to fatigue observed in thin ferroelectric films.Comment: 5 pages, REVTeX 3.1 with one eps-figure. A note added that the linear response is not changed by electromechanical effect. To appear in Phys. Rev.

Simultaneous existence of two spin-wave modes in ultrathin Fe/GaAs(001) films studied by Brillouin Light Scattering: experiment and theory

A double-peaked structure was observed in the {\it in-situ} Brillouin Light Scattering (BLS) spectra of a 6 \AA$$ thick epitaxial Fe/GaAs(001) film for values of an external magnetic field $H$, applied along the hard in plane direction, lower than a critical value $H_c\simeq 0.9$ kOe. This experimental finding is theoretically interpreted in terms of a model which assumes a non-homogeneous magnetic ground state characterized by the presence of perperpendicular up/down stripe domains. For such a ground state, two spin-wave modes, namely an acoustic and an optic mode, can exist. Upon increasing the field the magnetization tilts in the film plane, and for $H \ge H_{c}$ the ground state is homogeneous, thus allowing the existence of just a single spin-wave mode. The frequencies of the two spin-wave modes were calculated and successfully compared with the experimental data. The field dependence of the intensities of the corresponding two peaks that are present in the BLS spectra was also estimated, providing further support to the above-mentioned interpretation.Comment: Shortened version (7 pages). Accepted for publication in Physical Review

The Role of Self-Regulation in the Effect of Self-Tracking of Physical Activity and Weight on BMI

Self-tracking of health may have positive effects on lifestyle behavior and weight loss; however, not much is known about the role of psychological processes in this effect. The purpose of this study was to assess to what extent a change in self-regulation capabilities can explain weight loss after 4 and 12 months of self-tracking physical activity and weight. An explorative cohort study was conducted with measurements at baseline (T0), 4 months (T1), and 12 months (T2). Healthy adult volunteers (N = 80) were included and provided with a digital weight scale and an activity tracker. Personal characteristics as well as the intention to change weight and physical activity were measured at T0. Self-regulation capabilities (goal orientation, self-direction, decision making, and impulse control) were measured with the Self-Regulation Questionnaire at T0, T1, and T2, together with body weight. At T0, all four dimensions of self-regulation were negatively related to BMI (p <.01). At T1, weight significantly declined compared to T0 (− 2.0 kg/− 0.64 kg/m2, p <.001). At T2, this weight loss was maintained (− 1.8 kg/− 0.57 kg/m2, p <.01). At T1, intention to lose weight, self-weighing frequency, and an increase in goal orientation explained weight loss. At T2, an increase in decision making explained weight loss. Incremental self-regulation capabilities may explain weight loss after engaging in self-tracking of physical activity and weight. Future research should focus on exploring effective ways to further enhance self-regulation when using self-tracking technology and to assess the impact of different types of self-regulation stimuli on weight loss

Single-cell and neuronal network alterations in an in vitro model of Fragile X syndrome

The Fragile X mental retardation protein (FMRP) is involved in many cellular processes and it regulates synaptic and network development in neurons. Its absence is known to lead to intellectual disability, with a wide range of comorbidities including autism. Over the past decades, FMRP research focused on abnormalities both in glutamatergic and GABAergic signaling, and an altered balance between excitation and inhibition has been hypothesized to underlie the clinical consequences of absence of the protein. Using Fmrp knockout mice, we studied an in vitro model of cortical microcircuitry and observed that the loss of FMRP largely affected the electrophysiological correlates of network development and maturation but caused less alterations in single-cell phenotypes. The loss of FMRP also caused a structural increase in the number of excitatory synaptic terminals. Using a mathematical model, we demonstrated that the combination of an increased excitation and reduced inhibition describes best our experimental observations during the ex vivo formation of the network connections

Ionospheric quasi-static electric field anomalies during seismic activity in August–September 1981

The paper proposes new results, analyses and information for the plate tectonic situation in the processing of INTERCOSMOS-BULGARIA-1300 satellite data about anomalies of the quasi-static electric field in the upper ionosphere over activated earthquake source regions at different latitudes. The earthquake catalogue is made on the basis of information from the United State Geological Survey (USGS) website. The disturbances in ionospheric quasi-static electric fields are recorded by IESP-1 instrument aboard the INTERCOSMOS-BULGARIA-1300 satellite and they are compared with significant seismic events from the period 14 August–20 September 1981 in magnetically very quiet, quiet and medium quiet days. The main tectonic characteristics of the seismically activated territories are also taken in account. The main goal of the above research work is to enlarge the research of possible connections between anomalous vertical electric field penetrations into the ionosphere and the earthquake manifestations, also to propose tectonic arguments for the observed phenomena. The studies are represented in four main blocks: (i) previous studies of similar problems, (ii) selection of satellite, seismic and plate tectonic data, (iii) data processing with new specialized software and observations of the quasi-static electric field and (iiii) summary, comparison of new with previous results in our studies and conclusion. We establish the high informativity of the vertical component &lt;i&gt;Ez&lt;/i&gt; of the quasi-static electric field in the upper ionosphere according observations by INTERCOSMOS-BULGARIA-1300 that are placed above considerably activated earthquake sources. This component shows an increase of about 2–10 mV/m above sources, situated on mobile structures of the plates. The paper discusses the observed effects. It is represented also a statistical study of ionospheric effects 5–15 days before and 5–15 days after the earthquakes with magnitude M 4.8–7.9

Fetal alcohol exposure leads to abnormal olfactory bulb development and impaired odor discrimination in adult mice

Background: Children whose mothers consumed alcohol during pregnancy exhibit widespread brain abnormalities and a complex array of behavioral disturbances. Here, we used a mouse model of fetal alcohol exposure to investigate relationships between brain abnormalities and specific behavioral alterations during adulthood. Results: Mice drank a 10% ethanol so