The neurophysiological time pattern of illusionary visual perceptual transitions: a simultaneous EEG and fMRI study

Several divergent cortical mechanisms generating multistability in visual perception have been suggested. Here, we investigated the neurophysiologic time pattern of multistable perceptual changes by means of a simultaneous recording with electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Volunteers responded to the subjective perception of a sudden change between stable patterns of illusionary motion (multistable transition) during a stroboscopic paradigm. We found a global deceleration of the EEG frequency prior to a transition and an occipital-accentuated acceleration after a transition, as obtained by low-resolution electromagnetic tomography analysis (LORETA) analysis. A decrease in BOLD response was found in the prefrontal cortex before, and an increase after the transitions was observed in the right anterior insula, the MT/V5 regions and the SMA. The thalamus and left superior temporal gyrus showed a pattern of decrease before and increase after transitions. No such temporal course was found in the control condition. The multimodal approach of data acquisition allows us to argue that the top-down control of illusionary visual perception depends on selective attention, and that a diminution of vigilance reduces selective attention. These are necessary conditions to allow for the occurrence of a perception discontinuity in absence of a physical change of the stimulus.

The Territoriality of Fiscal Solidarity: Comparing Swiss Equalisation with European Union Structural Funding

This article theorises the territorial solidarity and fiscal federalism and compares Switzerland with the European Union. While inter-territorial solidarity is a prerequisite for legitimate fiscal equalisation, such equalisation in turn also contributes to the legitimacy of and solidarity within federal political systems. By cutting across territorial and ethno-national communities, fiscal transfers often contribute to both a “civic” sense of belonging and a “cosmopolitan” identity. After placing types and degrees of (inter-)territorial solidarity at the heart of our conceptual perspective, we discuss the effects of such solidarity through an analysis of two different forms of “federal” equalisation. Comparing the recently reformed Swiss fiscal equalisation system with the EU structural funds allows us to infer if, and how, the fiscal dimension of federalism matters for feelings of solidarity, reciprocity, unity and, ultimately, for the legitimacy of the very (nation-state or Union) structures that are to contribute to the ever-growing prosperity and happiness of their people(s). In Switzerland, a civic understanding of nationhood and cross-cutting cleavages were necessary conditions for extensive, effective and legitimate fiscal equalisation. We infer that, for the EU, this means that strengthening the equalisation component of the structural funds would contribute to an ever closer Union in a political sense: because fiscal equalisation and inter-territorial solidarity are interdependent, reinforcing the one also means cementing the other. Future studies of the EU and federal-type arrangements are advised to pay more explicit attention to the solidarity-element of territoriality – or the territoriality of (fiscal) solidarity.

Warum Pentose- und nicht Hexose-Nucleinsäuren??. Teil V. (Purin-Purin)-Basenpaarung in der homo-DNS-Reihe: Guanin, Isoguanin, 2,6-Diaminopurin und Xanthin

Why Pentose- and Not Hexose-Nucleic Acids? Purine-Purine Pairing in homo-DNA: Guanine,Isoguanine, 2,6-Diaminopurine, and Xanthine This paper concludes the series of reports in this journal [1–4] on the chemistry of homo-DNA, the constitutionally simplifie dmodel system of hexopyranosyl-(6′ → 4′)-oligonucleotide systems stidued in our laboratory as potentially natural-nucleic-acid alternatives in the context of a chemical aetiology of nucleic-acid structure. The report describes the synthesis and pairing properties of homo-DNA oligonucleotides which contain as nucleobases exclusively purines, and gives, together with part III of the series [3], a survey of what we know today about purine-purine pairingin homo-DNA. In addition, the paper discusses those aspects of the chemistry of homo-DNA which, we think, influence the way how some of the structural features of DNA (and RNA) are to be interpreted on a qualitative level. Purine-purine pairing occurs in the homo-DNA domain in great variety. Most prominent is a novel tridentate Watson-Crick pair between guanine and isoguanine, as well as one between 2,6-diaminopurine and xanthinone, both giving rise to very stable duplexes containing the all-purine strands in antiparallel orientation. For the guanine-isoguanine pair, constitutional assignment is based on temperature-dependent UV and CD spectroscopy of various guanine- and isoguanine-containg duplexes in comparison with duplexes known to be paired in the reverse guanine is replaced by 7-carbauguanine. Isoguanine and 2,6-diaminopurine also have the capability of self-pariring in the reverse-Hoogsteen mode, as previously observed for adenine and guanine [3]. In this type of pairing, the interchangeably. Fig. 36 provides an overall survey of the relative strength of pairing in all possible purine-purine combinations. Watson-Crick pairing of isoguanine with guanine demands the former to participate in its 3H-tautomeric form; hitherto this specific tautomer had not been considered in the pairing chemistry of isoguanine. Whereas (cumulative) purine-purine pairing in DNA (reverse-Hoogsten or Hoogsteen) seems to occur in triplexes and tetrapalexes only, its occurrence in duplexes in a characteristic feature of homo-DNA chemistry. The occurrence of purine-purine Watson-Crick base pairs is probably a consequence of homo-DNA's quasi-linear ladder structure [1][4]. In a double helix, the distance between the two sugar C-atoms, on which a base pair is anchored, is expected to be constrained by the dimensions of the helix; in a linear duplex, however, there would be no restrictions with regard to base-pair length. Homo-DNA's ladder-like model also allows one to recognize one of the reasons why nucleic-acid duplexes prefer to pair in antiparallel, rather than parallel strand orientation: in homo-DNA duplexes, (averaged) backbone and base pair axes are strongly inclined toward one another [4]; the stronger this inclination, the higher the preference for antiparallel strand orientation is expected to be (Fig. 16). In retrospect, homo-DNA turns out to be one of the first artificial oligonucleotide systems (cf. Footnote 65) to demonstrate in a comprehensive way that informational base pairing involving purines and pyrimidines is not a capability unique to ribofuranosyl systems. Stability and helical shape of pairing complexes are not necessary conditions of one another; it is the potential for extensive conformational cooperativity of hte backbone structure with respect to the constellational demands of base pairing and base stacking that determines whether or nor a given type of base-carrying backbone structure is an informational pairing system. From the viewpoint of the chemical aetiology of nucleic-acid structure, which inspired our investigations on hexopyranosyl-(6′ → 4′)-oligonucleotide systems in the first place, the work on homo-DNA is only an extensive model study, because homo-DNA is not to be considered a potential natural-nucleic-acid altenratie. In retrospect, it seems fortunate that the model study was carried out, because without it we could hardly have comprehended the pairing behavior of the proper nucleic-acid alternatives which we have studied later and which will be discussed in Part VI of this series. The English footnotes to Fig. 1–49 provide an extension of this summary.

A Maximum Radius for Habitable Planets

We compute the maximum radius a planet can have in order to fulfill two constraints that are likely necessary conditions for habitability: 1- surface temperature and pressure compatible with the existence of liquid water, and 2- no ice layer at the bottom of a putative global ocean, that would prevent the operation of the geologic carbon cycle to operate. We demonstrate that, above a given radius, these two constraints cannot be met: in the Super-Earth mass range (1-12 M-earth), the overall maximum that a planet can have varies between 1.8 and 2.3 R-earth. This radius is reduced when considering planets with higher Fe/Si ratios, and taking into account irradiation effects on the structure of the gas envelope.

Inhibition of SIRT1 Impairs the Accumulation and Transcriptional Activity of HIF-1α Protein under Hypoxic Conditions

Sirtuins and hypoxia-inducible transcription factors (HIF) have well-established roles in regulating cellular responses to metabolic and oxidative stress. Recent reports have linked these two protein families by demonstrating that sirtuins can regulate the activity of HIF-1 and HIF-2. Here we investigated the role of SIRT1, a NAD+-dependent deacetylase, in the regulation of HIF-1 activity in hypoxic conditions. Our results show that in hepatocellular carcinoma (HCC) cell lines, hypoxia did not alter SIRT1 mRNA or protein expression, whereas it predictably led to the accumulation of HIF-1α and the up-regulation of its target genes. In hypoxic models in vitro and in in vivo models of systemic hypoxia and xenograft tumor growth, knockdown of SIRT1 protein with shRNA or inhibition of its activity with small molecule inhibitors impaired the accumulation of HIF-1α protein and the transcriptional increase of its target genes. In addition, endogenous SIRT1 and HIF-1α proteins co-immunoprecipitated and loss of SIRT1 activity led to a hyperacetylation of HIF-1α. Taken together, our data suggest that HIF-1α and SIRT1 proteins interact in HCC cells and that HIF-1α is a target of SIRT1 deacetylase activity. Moreover, SIRT1 is necessary for HIF-1α protein accumulation and activation of HIF-1 target genes under hypoxic conditions.

A novel technique, dynamic intraligamentary stabilization creates optimal conditions for primary ACL healing: A preliminary biomechanical study

BACKGROUND Anterior cruciate ligament (ACL) rupture is a common lesion. Current treatment emphasizes arthroscopic ACL reconstruction via a graft, although this approach is associated with potential drawbacks. A new method of dynamic intraligamentary stabilization (DIS) was subjected to biomechanical analysis to determine whether it provides the necessary knee stability for optimal ACL healing. METHODS Six human knees from cadavers were harvested. The patellar tendon, joint capsule and all muscular attachments to the tibia and femur were removed, leaving the collateral and the cruciate ligaments intact. The knees were stabilized and the ACL kinematics analyzed. Anterior-posterior (AP) stability measurements evaluated the knees in the following conditions: (i) intact ACL, (ii) ACL rupture, (iii) ACL rupture with primary stabilization, (iv) primary stabilization after 50 motion cycles, (v) ACL rupture with DIS, and (vi) DIS after 50 motion cycles. RESULTS After primary suture stabilization, average AP laxity was 3.2mm, which increased to an average of 11.26mm after 50 movement cycles. With primary ACL stabilization using DIS, however, average laxity values were consistently lower than those of the intact ligament, increasing from an initial AP laxity of 3.00mm to just 3.2mm after 50 movement cycles. CONCLUSIONS Dynamic intraligamentary stabilization established and maintained close contact between the two ends of the ruptured ACL, thus ensuring optimal conditions for potential healing after primary reconstruction. The present ex vivo findings show that the DIS technique is able to restore AP stability of the knee.

The Genesis Solar Wind Concentrator: Flight and Post-Flight Conditions and Modeling of Instrumental Fractionation

The Genesis mission Solar Wind Concentrator was built to enhance fluences of solar wind by an average of 20x over the 2.3 years that the mission exposed substrates to the solar wind. The Concentrator targets survived the hard landing upon return to Earth and were used to determine the isotopic composition of solar-wind—and hence solar—oxygen and nitrogen. Here we report on the flight operation of the instrument and on simulations of its performance. Concentration and fractionation patterns obtained from simulations are given for He, Li, N, O, Ne, Mg, Si, S, and Ar in SiC targets, and are compared with measured concentrations and isotope ratios for the noble gases. Carbon is also modeled for a Si target. Predicted differences in instrumental fractionation between elements are discussed. Additionally, as the Concentrator was designed only for ions ≤22 AMU, implications of analyzing elements as heavy as argon are discussed. Post-flight simulations of instrumental fractionation as a function of radial position on the targets incorporate solar-wind velocity and angular distributions measured in flight, and predict fractionation patterns for various elements and isotopes of interest. A tighter angular distribution, mostly due to better spacecraft spin stability than assumed in pre-flight modeling, results in a steeper isotopic fractionation gradient between the center and the perimeter of the targets. Using the distribution of solar-wind velocities encountered during flight, which are higher than those used in pre-flight modeling, results in elemental abundance patterns slightly less peaked at the center. Mean fractionations trend with atomic mass, with differences relative to the measured isotopes of neon of +4.1±0.9 ‰/amu for Li, between -0.4 and +2.8 ‰/amu for C, +1.9±0.7‰/amu for N, +1.3±0.4 ‰/amu for O, -7.5±0.4 ‰/amu for Mg, -8.9±0.6 ‰/amu for Si, and -22.0±0.7 ‰/amu for S (uncertainties reflect Monte Carlo statistics). The slopes of the fractionation trends depend to first order only on the relative differential mass ratio, Δ m/ m. This article and a companion paper (Reisenfeld et al. 2012, this issue) provide post-flight information necessary for the analysis of the Genesis solar wind samples, and thus serve to complement the Space Science Review volume, The Genesis Mission (v. 105, 2003).

Comparison of morphological and rheological conditions between conventional and eversion carotid endarterectomy using computational fluid dynamics - a pilot study

PURPOSE To compare postoperative morphological and rheological conditions after eversion carotid endarterectomy versus conventional carotid endarterectomy using computational fluid dynamics. BASIC METHODS Hemodynamic metrics (velocity, wall shear stress, time-averaged wall shear stress and temporal gradient wall shear stress) in the carotid arteries were simulated in one patient after conventional carotid endarterectomy and one patient after eversion carotid endarterectomy by computational fluid dynamics analysis based on patient specific data. PRINCIPAL FINDINGS Systolic peak of the eversion carotid endarterectomy model showed a gradually decreased pressure along the stream path, the conventional carotid endarterectomy model revealed high pressure (about 180 Pa) at the carotid bulb. Regions of low wall shear stress in the conventional carotid endarterectomy model were much larger than that in the eversion carotid endarterectomy model and with lower time-averaged wall shear stress values (conventional carotid endarterectomy: 0.03-5.46 Pa vs. eversion carotid endarterectomy: 0.12-5.22 Pa). CONCLUSIONS Computational fluid dynamics after conventional carotid endarterectomy and eversion carotid endarterectomy disclosed differences in hemodynamic patterns. Larger studies are necessary to assess whether these differences are consistent and might explain different rates of restenosis in both techniques.

Determination of vertebral range of motion using inertial measurement units in 27 Franches-Montagnes stallions and comparison between conditions and with a mixed population

REASONS FOR PERFORMING STUDY: The diagnosis of equine back disorders is challenging. Objectively determining movement of the vertebral column may therefore be of value in a clinical setting. OBJECTIVES: To establish whether surface-mounted inertial measurement units (IMUs) can be used to establish normal values for range of motion (ROM) of the vertebral column in a uniform population of horses trotting under different conditions. STUDY DESIGN: Vertebral ROM was established in Franches-Montagnes stallions and a general population of horses and the variability in measurements compared between the two groups. Repeatability and the influence of specific exercise condition (on ROM) were assessed. Finally, attempts were made to explain the findings of the study through the evaluation of factors that might influence ROM. METHODS: Dorsoventral (DV) and mediolateral (ML) vertebral ROM was measured at a trot under different exercise conditions in 27 Franches-Montagnes stallions and six general population horses using IMUs distributed over the vertebral column. RESULTS: Variability in the ROM measurements was significantly higher for general population horses than for Franches-Montagnes stallions (both DV and ML ROM). Repeatability was strong to very strong for DV measurements and moderate for ML measurements. Trotting under saddle significantly reduced the ROM, with sitting trot resulting in a significantly lower ROM than rising trot. Age is unlikely to explain the low variability in vertebral ROM recorded in the Franches-Montagnes horses, while this may be associated with conformational factors. CONCLUSIONS: It was possible to establish a normal vertebral ROM for a group of Franches-Montagnes stallions. While within-breed variation was low in this population, further studies are necessary to determine variation in vertebral ROM for other breeds and to assess their utility for diagnosis of equine back disorders.