Asymptotically Optimal Solutions for Small World Graphs

We consider the problem of determining constructions with an asymptotically optimal oblivious diameter in small world graphs under the Kleinberg’s model. In particular, we give the first general lower bound holding for any monotone distance distribution, that is induced by a monotone generating function. Namely, we prove that the expected oblivious diameter is Ω(log ² n) even on a path of n nodes. We then focus on deterministic constructions and after showing that the problem of minimizing the oblivious diameter is generally intractable, we give asymptotically optimal solutions, that is with a logarithmic oblivious diameter, for paths, trees and Cartesian products of graphs, including d-dimensional grids for any fixed value of d. The research was partially funded by the European project COST Action 293, “Graphs and Algorithms in Communication Networks” (GRAAL).     

Clinical experience of osteoarticular MRI using a dedicated system

Magnetic resonance imaging (MRI) has a significative impact on diagnosis of musculoskeletal diseases. At present, joint diseases are evaluated with total-body systems, this fact representing an obstacle to MR diffusion in the osteoarticular field. The last technological advances have allowed the development of a cost-effective, compact and easy-to-install MR system. The system is constituted by a 0.2-T permanent unit, weighing 800 kg. The unit is used only for limb examination. To verify the diagnostic accuracy of the new system a study based on 1902 lower limb examinations was carried out between October 1992 and February 1994. Of these patients, 301 underwent surgery during which the MR findings were verified. Quite satisfying overall results were obtained, particularly in case of knee trauma, comparable to those provided by total body units with higher magnetic field. It must be noted, however, that in 3% of the investigated knee diseases, the examinations could not be performed due to technical limitations related to the magnet size. The authors believe that the limited field of view (11 cm) does not allows accurate staging of the malignant lesions concerning soft tissue and bone, which require a wider loco-regional staging. They also believe that the particular structure of the magnet allows for a comfortable management of pediatric, elderly, and acute patients.     

Bone marrow cells of swine: collection and separation

Bone marrow is a source of stem cells for greater and easier access, which is widely studied as a provider of hematopoietic and mesenchymal cells for various purposes, mainly therapeutic by the advances in research involving cell therapy. The swine is an animal species commonly used in the pursuit of development of experimental models. Thus, this study aimed to standardize protocol for collection and separation of bone marrow in swines, since this species is widely used as experimental models for various diseases. Twelve animals were used, which underwent bone marrow puncture with access from the iliac crest and cell separation by density gradient followed by a viability test with an average of 98% of viable cells. Given our results, we can ensure the swine as an excellent model for obtaining and isolation of mononuclear cells from bone marrow, stimulating several studies addressing the field of cell therapy.     

Controlled Release of Epigenetically-Enhanced Extracellular Vesicles from a GelMA/Nanoclay Composite Hydrogel to Promote Bone Repair

Extracellular vesicles (EVs) have garnered growing attention as promising acellular tools for bone repair. Although EVs’ potential for bone regeneration has been shown, issues associated with their therapeutic potency and short half-life in vivo hinders their clinical utility. Epigenetic reprogramming with the histone deacetylase inhibitor Trichostatin A (TSA) has been reported to promote the osteoinductive potency of osteoblast-derived EVs. Gelatin methacryloyl (GelMA) hydrogels functionalised with the synthetic nanoclay laponite (LAP) have been shown to effectively bind, stabilise, and improve the retention of bioactive factors. This study investigated the potential of utilising a GelMA-LAP hydrogel to improve local retention and control delivery of epigenetically enhanced osteoblast-derived EVs as a novel bone repair strategy. LAP was found to elicit a dose-dependent increase in GelMA compressive modulus and shear-thinning properties. Incorporation of the nanoclay was also found to enhance shape fidelity when 3D printed compared to LAP-free gels. Interestingly, GelMA hydrogels containing LAP displayed increased mineralisation capacity (1.41-fold) (p ≤ 0.01) over 14 days. EV release kinetics from these nanocomposite systems were also strongly influenced by LAP concentration with significantly more vesicles being released from GelMA constructs as detected by a CD63 ELISA (p ≤ 0.001). EVs derived from TSA-treated osteoblasts (TSA-EVs) enhanced proliferation (1.09-fold), migration (1.83-fold), histone acetylation (1.32-fold) and mineralisation (1.87-fold) of human bone marrow stromal cells (hBMSCs) when released from the GelMA-LAP hydrogel compared to the untreated EV gels (p ≤ 0.01). Importantly, the TSA-EV functionalised GelMA-LAP hydrogel significantly promoted encapsulated hBMSCs extracellular matrix collagen production (≥1.3-fold) and mineralisation (≥1.78-fold) in a dose-dependent manner compared to untreated EV constructs (p ≤ 0.001). Taken together, these findings demonstrate the potential of combining epigenetically enhanced osteoblast-derived EVs with a nanocomposite photocurable hydrogel to promote the therapeutic efficacy of acellular vesicle approaches for bone regeneration.     

Oxytocin release is inhibited by the generation of carbon monoxide from the rat hypothalamus--further evidence for carbon monoxide as a neuromodulator

Recent evidence suggests that the gas nitric oxide can modulate the secretion of a number of hypothalamic hormones, and may be co-localized particularly to oxytocin-containing neurons. Another gas, carbon monoxide (CO), has also been suggested to play a role in neural signaling in the brain, and the synthetic enzyme responsible for the generation of carbon monoxide has been reported to be present in the rat hypothalamus. In this study, we have therefore investigated whether CO has the ability to modify the release of oxytocin from acute rat hypothalamic explants. Hemin, a specific CO precursor through the enzyme heme oxygenase (the enzymatic pathway synthesizing endogenous CO, was found to inhibit KCl-stimulated oxytocin release, with a maximal effect at 10(-5) M, while showing no effect on basal oxytocin secretion. The stimulation of oxytocin by serotonin 10 ng/ml was also significantly antagonized by hemin 10(-7) M. An inhibitor of heme oxygenase, zinc-protoporphyrin-9, had no effect on basal or stimulated oxytocin release. When hemin and zinc-protoporphyrin-9 were given together, the hemin-induced inhibition of oxytocin was completely antagonized by the enzyme inhibitor. Ferrous hemoglobin A0, a substance known to bind CO with high affinity, had no effect on either basal or stimulated oxytocin release, but when hemin and ferrous hemoglobin A0 were given together the hemin-induced inhibition of oxytocin was completely blocked. These findings provide evidence that endogenous CO may play a role in the control of oxytocin release and that, by analogy with nitric oxide, CO may represent a major new neuroendocrine modulator.     

Silica encapsulating lanthanum complexes using the sol–gel technique

BACKGROUND: Because of its properties, silica gel is an excellent host for different compounds. Many types of chemical species (organics, organometallics, proteins, enzymes, etc.) can be encapsulated in xerogels, and the sol–gel technique has been shown to be very useful for this aim. RESULTS: Some host–guest systems based on silica and complexed lanthanum were prepared in order to develop fluorescence properties. Three pathways were used to prepare such systems: (1) obtaining the lanthanum complex with a dimethylsiloxane‐based ligand and its incorporation into a silica network; (2) preparation of a silica network having hydroxyazomethine groups and in situ lanthanum complexation; and (3) preparation of polydimethylsiloxane (PDMS)/silica composites that possess hydroxyazomethine groups on the silica and in situ lanthanum complexation. The sol–gel technique was used in all cases. CONCLUSION: The photophysical properties of the prepared compounds were evaluated using fluorescence spectroscopy. The investigations revealed that the systems belonging to the second series are the most fluorescent. In the third series, the presence of PDMS provokes a decrease of the fluorescence intensity, until its complete quenching when the PDMS content exceeds a certain threshold value. However, there is a range of silica/PDMS ratio for which fluorescent free‐standing films can be obtained. The presence of complexed lanthanum induces changes in the morphology of the silica/PDMS matrix, as evidenced by scanning electron microscopy studies. Copyright © 2008 Society of Chemical Industry     

The Perception of Second Language Sounds in Early Bilinguals: New Evidence From an Implicit Measure.

Previous studies have suggested that nonnative (L2) linguistic sounds are accommodated to native language (L1) phonemic categories. However, this conclusion may be compromised by the use of explicit discrimination tests. The present study provides an implicit measure of L2 phoneme discrimination in early bilinguals (Catalan and Spanish). Participants classified the 1st syllable of disyllabic stimuli embedded in lists where the 2nd, task-irrelevant, syllable could contain a Catalan contrastive variation (/ε/-/e/) or no variation. Catalan dominants responded more slowly in lists where the 2nd syllable could vary from trial to trial, suggesting an indirect effect of the /ε/-/e/ discrimination. Spanish dominants did not suffer this interference, performing indistinguishably from Spanish monolinguals. The present findings provide implicit evidence that even proficient bilinguals categorize L2 sounds according to their L1 representations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Improved Approximation Results for the Minimum Energy Broadcasting Problem

In this paper we present new results on the performance of the Minimum Spanning Tree heuristic for the Minimum Energy Broadcast Routing (MEBR) problem. We first prove that, for any number of dimensions d≥2, the approximation ratio of the heuristic does not increase when the power attenuation coefficient α, that is the exponent to which the coverage distance must be raised to give the emission power, grows. Moreover, we show that, for any fixed instance, as a limit for α going to infinity, the ratio tends to the lower bound of Clementi et al. (Proceedings of the 18th annual symposium on theoretical aspects of computer science (STACS), pp. 121–131, 2001), Wan et al. (Wirel. Netw. 8(6):607–617, 2002) given by the d-dimensional kissing number, thus closing the existing gap between the upper and the lower bound. We then introduce a new analysis allowing to establish a 7.45-approximation ratio for the 2-dimensional case, thus significantly decreasing the previously known 12 upper bound (Wan et al. in Wirel. Netw. 8(6):607–617, 2002) (actually corrected to 12.15 in Klasing et al. (Proceedings of the 3rd IFIP-TC6 international networking conference, pp. 866–877, 2004)). Finally, we extend our analysis to any number of dimensions d≥2 and any α≥d, obtaining a general approximation ratio of 3 ^d −1, again independent of α. The improvements of the approximation ratios are specifically significant in comparison with the lower bounds given by the kissing numbers, as these grow at least exponentially with respect to d. The research was partially funded by the European project COST Action 293, “Graphs and Algorithms in Communication Networks” (GRAAL). Preliminary version of this paper appeared in Flammini et al. (Proceedings of ACM joint workshop on foundations of mobile computing (DIALM-POMC), pp. 85–91, 2004).     

The use of prosthetic meshes in the surgical treatment of inguinal hernia: the costs and profits for the local health screening unit]

BACKGROUND: The appropriate timing of elective coronary artery bypass surgery (CABG) following acute myocardial infarction (AMI) remains uncertain. It is hypothesized that a waiting period allows the myocardium to recover prior to revascularization, thus decreasing morbidity and mortality. This study was designed to determine if a waiting strategy is justified following AMI in patients requiring elective CABG. METHODS: Between 1994 and 1996, 214 patients underwent isolated, nonrepeat, elective CABG. Three groups were evaluated: group I, control, 155 patients with no AMI; group 11, 39 patients with nontransmural AMI; and Group III, 20 patients with transmural AMI. Demographics, intraoperative, and postoperative variables were collected and compared among all groups. RESULTS: Groups were well-matched demographically: group I, patients waited an average of 2.3 days in hospital prior to operation; group II, an average of 4.2 days; and group III, an average of 5.2 days. Except for the use of inotropes, group I 34%, group 11 39%, and group III 70% (P = 0.007), and the intra-aortic balloon pump, group I 0%, group 11 8%, and group III 25% (P = 0.001). There were no differences in complications. Importantly, there was no difference in mortality or postoperative length of stay. The mortality in group I was 2.6%, in group 11 2.6%, and in group III 0%. The length of stay in groups I and II was 8.5 days, and in group III, 8.1 days. CONCLUSION: A waiting period of 3 to 5 days after a nontransmural AMI and 5 to 7 days after a transmural AMI can produce similar postoperative results to non-AMI patients undergoing CABG. Thus, a waiting strategy to allow the myocardium to recover is justified.     

Thermal oxidative process in extra-virgin olive oils studied by FTIR,rheology and time-resolved luminescence

With the aim to characterise the antioxidant properties of different extra-virgin olive oils and to understand in more detail the mechanisms of oil degradation, we have made an experimental study on thermal induced oxidative processes of extra-virgin olive oils by using different techniques: Fourier Transform Infrared (FTIR) spectroscopy, rheology and time-resolved luminescence. The oxidation process was followed at three different heating temperatures (30, 60 and 90 °C) as a function of time up to 35 days. Thermal treatment induced changes in the FTIR spectra in the wavenumbers region 3100–3600 cm⁻¹: in particular, the absorption profiles show an initial formation of hydroperoxides and a subsequent increase of alcohols and secondary oxidation products. In agreement with the FTIR data, rheology measurements show that after thermal treatment all examined samples exhibit an increase in the viscosity values with respect to pristine ones, indicating that the heat treatment induces the formation of polar molecules with propensity to form hydrogen bonds, which has as a consequence a viscosity increase. Finally, a lifetime increase of luminescence of chlorophyll is observed in agreement with the viscosity rise. Indeed, the viscosity increase reduces the frequency of collisions between the chromophore and its environment, consequently lowering the non-radiative contribution to the luminescence decay.