On the sources of the Great Moderation

The remarkable decline in macroeconomic volatility experienced by the U.S. economy since the mid-80s (the so-called Great Moderation) has been accompanied by large changes in the patterns of comovements among output, hours and labor productivity. Those changes are reflected in both conditional and unconditional second moments as well as in the impulse responses to identified shocks. That evidencepoints to structural change, as opposed to just good luck, as an explanation for the Great Moderation. We use a simple macro model to suggest some of the immediate sources which are likely to be behindthe observed changes.

Previous microvascular decompression decreases the chances of pain free in patients treated with Gamma Knife radiosurgery for TIC

Object: The authors sought to establish whether the safety-efficacy of Gamma Knife radiosurgery (GKRS) as a second treatment for intractable trigeminal neuralgia (ITN) are influenced by prior microvascular decompression (MVD) which remains, for some of the authors, the reference technique. Methods: Between July 1992 and November 2010, 737 patients have been operated with GKRS for ITN and prospectively evaluated in Timone University Hospital in Marseille, France. Among these, 54 patients had a previous MVD history. Radiosurgery using a Gamma Knife (model B or C or Perfexion) was performed relying on both MR and CT targeting. A single 4 mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range 3.9- 11.9) anteriorly to the emergence of the nerve (retrogasserian target). A median maximum dose of 85 Gy (range 70-90) was delivered. Are further analyzed only 45 patients with previous MVD and a follow-up longer than one year (the patients with megadolichobasilar artery compression and multiple sclerosis were excluded). Results: The median age in this series was 56.75 years (range 28.09-82.39). The median follow-up period was 39.48 months (range 14.10-144.65). All the patients had a past history of surgery, with at least one previous failed MVD, but also a radiofrequency lesion (RFL) in 16 (35.6%) patients, balloon microcompression in 7 (15.6%) patients and glycerol rhizotomy in 1 case (2.2%). Thirty-five patients (77.8%) were initially pain free in a median time of 14 days (range 0, 180). Patients from this group had less probability of being pain free compared to our global population of essential trigeminal neuralgia without previous MVD history (p=0.010, hazard ratio of 0.64). Their probability of remaining pain free at 3, 5, 7 and 10 years was 66.5%, 59.1%, 59.1% and 44.3%, respectively. Twelve patients (34.3%) initially pain free experienced a recurrence with a median delay of 31.21 months (range 3.40-89.93). The hypoesthesia actuarial rate at 1 year was 9.1% and remained stable till 12 years with a median delay of onset of 8 months (range 8-8). Conclusions: Retrogasserian GKRS proofed to be safe and effective on the long-term basis even after failed previous MVD. Even if the initial result of pain free was of only 77.8%, the toxicity was low with only 9.1% hypoesthesia. No patient reported a bothersome hypoesthesia. The probability of maintaining pain relief in long-term was of 44.3% at 10 years.

External technology sources: Embodied or disembodied technology acquisition

This paper analyzes the choice between different innovationactivities of a firm. In particular, we study the technologyacquisition decision of the firm, i.e. its technology BUYdecision as part of the firm's innovation strategy. We take a closer look at the different types of external technologyacquisition where we distinguish two broad types of technologybuy decisions. On the one hand, the firm can acquire new technology which is embodied in an asset that is acquired suchas new personnel or (parts of) other firms or equipment. On the other hand, the firm can obtain new technology disembodiedthrough a licensing agreement or by outsourcing the technologydevelopment from an R&D contractor or consulting agency. Through a series of Probit regressions, we discuss variables that might affect external technology acquisition choices of the firm andpay special attention to the firm's abilities to scan the market for technology and to absorb the technology acquired. Furthermore, we analyze the effect of different appropriationregimes on the decision of the firm to source technology.

A neuronal gamma oscillatory signature during morphological unification in the left occipitotemporal junction.

Morphology is the aspect of language concerned with the internal structure of words. In the past decades, a large body of masked priming (behavioral and neuroimaging) data has suggested that the visual word recognition system automatically decomposes any morphologically complex word into a stem and its constituent morphemes. Yet the reliance of morphology on other reading processes (e.g., orthography and semantics), as well as its underlying neuronal mechanisms are yet to be determined. In the current magnetoencephalography study, we addressed morphology from the perspective of the unification framework, that is, by applying the Hold/Release paradigm, morphological unification was simulated via the assembly of internal morphemic units into a whole word. Trials representing real words were divided into words with a transparent (true) or a nontransparent (pseudo) morphological relationship. Morphological unification of truly suffixed words was faster and more accurate and additionally enhanced induced oscillations in the narrow gamma band (60-85 Hz, 260-440 ms) in the left posterior occipitotemporal junction. This neural signature could not be explained by a mere automatic lexical processing (i.e., stem perception), but more likely it related to a semantic access step during the morphological unification process. By demonstrating the validity of unification at the morphological level, this study contributes to the vast empirical evidence on unification across other language processes. Furthermore, we point out that morphological unification relies on the retrieval of lexical semantic associations via induced gamma band oscillations in a cerebral hub region for visual word form processing.

Low density polyethylene (LDPE) passive samplers for the investigation of polychlorinated biphenyl (PCB) point sources in rivers

This study aims to provide a passive sampling approach which can be routinely used to investigate polychlorinated biphenyl (PCB) sources in rivers. The approach consists of deploying low density polyethylene (LDPE) strips downstream and upstream of potential PCB sources as well as in their water discharges. Concentrations of indicator PCBs (iPCBs) absorbed in samplers (Cs) from upstream and downstream sites are compared with each other to reveal increases of PCB levels. Cs measured in water discharges are used to determine if released amounts of PCBs are compatible with increases revealed in the river. As water velocity can greatly vary along a river stretch and influences the uptake at each site in a different way, differences in velocity have to be taken into account to correctly interpret Cs. LDPE strips were exposed to velocities between 1.6 and 37 cm s−1 using a channel system built in the field. Relationships between velocity and Cs were established for each iPCB to determine the expected change in Cs due to velocity variations. For PCBs 28 and 52, this change does not exceed a factor 2 for velocity variations in the range from 1.6 to 100 cm s−1 (extrapolated data above 37 cm s−1). For PCBs 101, 138, 153 and 180, this change only exceeds a factor 2 in the case of large velocity variations. The approach was applied in the Swiss river Venoge to first conduct a primary investigation of potential PCB sources and then conduct thorough investigations of two suspected sources.

Nuclear well logging in soils. Calibration of slim hole nuclear tools gamma-gamma and neutron-thermal neutron.

The calculation of elasticity parameters by sonic and ultra sonic wave propagation in saturated soils using Biot's theory needs the following variables : forpiation density and porosity (p, ø), compressional and shear wave velocities (Vp, Vs), fluid density, viscosity and compressibility (Pfi Ilfi Ki), matrix density and compressibility (p" K), The first four parameters can be determined in situ using logging probes. Because fluid and matrix characteristics are not modified during core extraction, they can be obtained through laboratory measurements. All parameters necessitate precise calibrations in various environments and for specific range of values encountered in soils. The slim diameter of boreholes in shallow geophysics and the high cost of petroleum equipment demand the use of specific probes, which usually only give qualitative results. The measurement 'of density is done with a gamma-gamma probe and the measurement of hydrogen index, in relation to porosity, by a neutron probe. The first step of this work has been carried out in synthetic formations in the laboratory using homogeneous media of known density and porosity. To establish borehole corrections different casings have been used. Finally a comparison between laboratory and in situ data in cored holes of known geometry and casing has been performed.

Fat poetry: a kingdom for PPAR gamma.

Adipose tissue is not an inert cell mass contributing only to the storage of fat, but a sophisticated ensemble of cellular components with highly specialized and complex functions. In addition to managing the most important energy reserve of the body, it secretes a multitude of soluble proteins called adipokines, which have beneficial or, alternatively, deleterious effects on the homeostasis of the whole body. The expression of these adipokines is an integrated response to various signals received from many organs, which depends heavily on the integrity and physiological status of the adipose tissue. One of the main regulators of gene expression in fat is the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), which is a fatty acid- and eicosanoid-dependent nuclear receptor that plays key roles in the development and maintenance of the adipose tissue. Furthermore, synthetic PPARgamma agonists are therapeutic agents used in the treatment of type 2 diabetes.This review discusses recent knowledge on the link between fat physiology and metabolic diseases, and the roles of PPARgamma in this interplay via the regulation of lipid and glucose metabolism. Finally, we assess the putative benefits of targeting this nuclear receptor with still-to-be-identified highly selective PPARgamma modulators.