Single-shot terahertz time-domain spectrometer using 1550 nm probe pulses and diversity electro-optic sampling.

Classical terahertz spectroscopy usually requires the use of Fourier transform or Time-Domain Spectrometers. However, these classical techniques become impractical when using recent high peak power terahertz sources - based on intense lasers or accelerators - which operate at low repetition rate. We present and test the design of a novel Time-Domain Spectrometer, that is capable of recording a whole terahertz spectrum at each shot of the source, and that uses a 1550 nm probe fiber laser. Single-shot operation is obtained using chirped-pulse electro-optic sampling in Gallium Arsenide, and high bandwidth is obtained by using the recently introduced Diversity Electro-Optic Sampling (DEOS) method. We present the first real-time measurements of THz spectra at the TeraFERMI Coherent Transition Radiation source. The system achieves 2.5 THz bandwidth with a maximum dynamic range reaching up to 25 dB. By reducing the required measurement time from minutes to a split-second, this strategy dramatically expands the application range of high power low-repetition rate THz sources.

Possible light-induced superconductivity in K3C60 at high temperature.

The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects such as the optical enhancement of superconductivity. Nonlinear excitation of certain phonons in bilayer copper oxides was recently shown to induce superconducting-like optical properties at temperatures far greater than the superconducting transition temperature, Tc (refs 4-6). This effect was accompanied by the disruption of competing charge-density-wave correlations, which explained some but not all of the experimental results. Here we report a similar phenomenon in a very different compound, K3C60. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. These same signatures are observed at equilibrium when cooling metallic K3C60 below Tc (20 kelvin). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this as a possible explanation of our results.

Terahertz Tuning of Dirac Plasmons in Bi_{2}Se_{3} Topological Insulator.

Light can be strongly confined in subwavelength spatial regions through the interaction with plasmons, the collective electronic modes appearing in metals and semiconductors. This confinement, which is particularly important in the terahertz spectral region, amplifies light-matter interaction and provides a powerful mechanism for efficiently generating nonlinear optical phenomena. These effects are particularly relevant in graphene and topological insulators, where massless Dirac fermions show a naturally nonlinear optical behavior in the terahertz range. The strong interaction scenario has been considered so far from the point of view of light. In this Letter, we investigate instead the effect of strong interaction on the plasmon itself. In particular, we will show that Dirac plasmons in Bi_{2}Se_{3} topological insulator are strongly renormalized when excited by high-intensity terahertz radiation by displaying a huge red-shift down to 60% of its characteristic frequency. This opens the road towards tunable terahertz nonlinear optical devices based on topological insulators.

Neurotrophin-mimicking peptides at the biointerface with gold respond to copper ion stimuli.

The peptide fragments NGF1-14 and BDNF1-12, encompassing the N-terminal domains, respectively, of the proteins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were used in this study for the fabrication of a hybrid gold/peptide biointerface. These peptides mimic the Trk receptor activation of the respective whole protein - with a crucial role played by copper ions - and exhibit, in bulk solution, a pH-dependent capability to complex copper. We demonstrate here the maintenance of peptide-specific responses at different pH values as well as the copper binding also for the adlayers formed upon physisorption at the gold surface. The physicochemical properties, including viscoelastic behavior of the adlayer and competitive vs. synergic interactions in sequential adsorption processes, were addressed both experimentally, by quartz crystal microbalance with dissipation monitoring (QCM-D) and circular dichroism (CD), and theoretically, by molecular dynamics (MD) calculations. Proof-of work biological assays with the neuroblastoma SY-SH5H cell line demonstrated that the developed hybrid Au/peptide nanoplatforms are very promising for implementation in pH- and metal-responsive systems for application in nanomedicine.

Spectral Weight Redistribution in (LaNiO3)n/(LaMnO3)2 Superlattices from Optical Spectroscopy.

We have studied the optical properties of four (LaNiO3)n/(LaMnO3)2 superlattices (SL) (n=2,3,4,5) on SrTiO3 substrates. We have measured the reflectivity at temperatures from 20 to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO3 thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad midinfrared band, however, shows that the optical conductivity of the (LaNiO3)n/(LaMnO3)2 SLs is not a linear combination of the LaMnO_{3} and LaNiO3 conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.

Validation of a web-based questionnaire to assess the dietary intake of Brazilian children aged 7-10 years.

BACKGROUND: The Food Intake and Physical Activity of School Children (CAAFE) comprises an online questionnaire to self-report diet and physical activity of Brazilian schoolchildren. BACKGROUND: The present study aimed to assess the validity (matches, omissions and intrusions) and moderating factors of the CAAFE. METHODS: Direct observation was made of foods consumed (five public schools) and child self-reporting on the CAAFE. Additional data included school grade, gender, body mass index, completion of food diary, socioeconomic status and access to computer. Data were analysed using regression. RESULTS: In total, 602 children participated in the study [mean (SD) age 9.5 (1.24) years; 53.6% boys]. On average, there were 43% matches, 29% intrusions and 28% omissions. Matches doubled in third grade compared to the second grade (P = 0.004); matches almost tripled for afternoon snack compared to morning snack (P < 0.001); and matches were 69% higher for children with access to a computer at home (P < 0.01). Intrusions decreased by almost one-half in fifth compared to fourth grades (P = 0.004). Omissions declined significantly in the third and fourth grades but increased in the fifth grade. Omissions were 47% lower for children in the highest income and lower among children who completed the food diary. No differences were found for gender or body mass index. CONCLUSIONS: Children older than 8 years old, who owned a computer and completed a food diary, performed better in the CAAFE. A high incidence of disagreement was found in relation to the schools and the type of meal. Overall matches (43%), intrusions (29%) and omissions (28%) indicate that further studies are required to improve the validity of the CAAFE.

Qualitative analysis of the contributions of nutritionists to the development of an online instrument for monitoring the food intake of schoolchildren.

BACKGROUND: The Consumo Alimentar e Atividade Fisica de Escolares (CAAFE) questionnaire is an online research tool that has been developed to enable the self-report of physical activity and diet by Brazilian schoolchildren aged 7-10 years. Formative research was conducted with nutritionists during the development of the web-based questionnaire. The suggestions and insights obtained were used to design a tool to monitor schoolchildren's food consumption based on the concept of healthy and unhealthy food indicators. The present study aimed to report the focus group discussions conducted with nutritionists concerning the CAAFE questionnaire. METHODS: Focus group discussions were conducted using a semi-structured questionnaire, and these were then analysed thematically. RESULTS: Twenty-four nutritionists participated (four focus groups; average per group: six people); the majority (n = 22) had experience with 7-10-year-old children. Four themes emerged: (i) healthy and unhealthy food indicators; (ii) suggestions for the online instrument; (iii) potential applications; and (iv) challenges for its construction. CONCLUSIONS: Comments made by nutritionists enabled the construction of an instrument that is able to answer questions related to food consumption in schools and at home.

Lipid nano-vesicles for thyroid hormone encapsulation: A comparison between different fabrication technologies, drug loading, and an in vitro delivery to human tendon stem/progenitor cells in 2D and 3D culture.

Phosphatidylcholine (PC) vesicles loaded with Triiodothyronine (T3) were fabricated using different manufacturing methods: thin layer hydration plus sonication (TF-UF), supercritical liposome formation (SC), and microfluidic technology (MF). Vesicles obtained by MF had the lowest mean diameter (88.61 ± 44.48 nm) with a Zeta Potential of -20.1 ± 5.90 mV and loading of 10 mg/g (encapsulation efficiency: 57%). In contrast, SC vesicles showed extremely low encapsulation efficiency (<10%) probably due to T3 solubility in ethanol/carbon dioxide mixture; despite TF-UF vesicles exhibiting good size (167.7 ± 90 nm; Zp -8.50 ± 0.60 mV) and loading (10 mg/g), poor mass recovery was obtained (50% loss). MF vesicles had low cytotoxicity, and they were well enough internalized by both HeLa and human tendon stem/progenitor cells (hTSPCs). Their biological activity was also monitored in both 2D and 3D cultures of hTSPCs supplemented with therapeutical concentrations of PC/T3 nano-liposomes. 2D culture showed almost similar constitutive gene expression compared to control culture supplemented with free-T3. On the contrary, when hTPSCs 3D culture was assembled, it showed a more evident homogeneous distribution of FITC labeled vesicles within the high-density structure and a significant upregulation of cell constitutive genes, such as type I Collagen (4.8-fold; p < 0.0001) at day 7, compared to the control, suggesting that T3/PC formulation has increased T3 cytosolic concentration, thus improving cells metabolic activity. The study supported MF technology for nano-carriers fabrication and opens perspectives on the activity of PC/T3 nano-vesicles as innovative formulations for TPSCs stimulation in ECM secretion.

Burden of rotavirus infections in Liguria, Northern Italy: hospitalisations and potential savings by vaccination.

We evaluated the rates of gastroenteritis admissions to the emergency department and of rotavirus-related hospitalisations in children ≤5 years of age in 2006 at an Italian paediatric hospital. We calculated the number of rotavirus cases avoidable through the universal vaccination of children. Epidemiological data were extracted from the Data Elaboration Centre. To calculate the hospitalisation rate due to rotavirus, the virus was sought in the faeces of children hospitalised for acute gastroenteritis by means of rapid immunochromatographic assay. Emergency department admissions due to gastroenteritis numbered 2,396 (11.58% of the total admissions). Of these, 276 children (11.52%) were examined and then sent home, 1,286 (53.67%) were kept in short observation and 776 (32.38%) were hospitalised. In 27.83% of hospitalised cases, the rotavirus test proved positive. The rotavirus hospitalisation rate was 55 per 10,000 children ≤5 years of age in Genoa in 2006. In 85.6% of hospitalised patients with community-acquired rotavirus infection, the disease was severe. The number of avoidable cases confirmed that the vaccination of children ≤1 year of age could reduce the burden of rotavirus infection, especially with regard to hospitalisation (45 per 10,000 children ≤5 years of age) and admissions to short observation (85 per 10,000), generating benefits for the Italian healthcare system.

Clinical evaluation and treatment of acute asthma exacerbations in children.

This update on treatment of asthma exacerbations in children is the result of an Italian Pediatric Society Task-force, made up of a panel of experts working in 2007-2008. The aim is to give clear indications on the use of the drugs most employed in children, grading the quality of evidence and the strength of recommendations. Suggestions on their limits due to unlicensed and off-label use are reported. The level of evidence and the strength of recommendations for different therapeutic approaches demonstrate that frequently the use of drugs in children is extrapolated from the experience in adults and that more studies are required to endorse the correct use of different drugs in asthmatic children.

Methylated tin toxicity a reappraisal using rodents models.

Trimethyltin-induced intoxication has a great impact on human health due to the widespread occurrence of methyltin compounds. Acute TMT intoxication in humans leads to a variety of neurological symptoms which involve primarily the limbic system. In the present review we summarized the neuromorphological correlates of this neurological syndrome extending the analysis to various extra-limbic regions and detailing the fine ultrastructure of TMT-induced neuronal alterations. In order to comprehend the pathophysiology of TMT-induced neuronal damage we analysed the various experimental models of TMT-induced neurotoxicity. When comparing various animal species, it seems that the variety of neuropathological correlates are not related to species difference in the sensitivity to TMT toxicity but to a different susceptibility to secondary effects produced by TMT. In fact, apart from a primary neurotoxic damage induced by TMT at neuronal level, this compound promotes the onset of limbic and generalized seizures, which in turn add a secondary damage to that induced immediately by TMT. Thus, the different neuropathology observed in different animal species is produced mainly by a different sensitivity to epilepsy-induced brain damage.

A bioavailability study on microbeads and nanoliposomes fabricated by dense carbon dioxide technologies using human-primary monocytes and flow cytometry assay.

Supercritical Emulsion Extraction (SEE) and Supercritical assisted Liposome formation (SuperLip), use dense gases such as carbon dioxide (dCO2) to fabricate advanced micro/nanocarriers. SEE uses dCO2 to extract solvent from the oily phase of an emulsion and obtain biopolymer microbead; For this study, poly-Lactic Acid (PLA) microbeads of 1 ±â€¯0.2 µm in mean size loaded at 1 µg/mgPLA with Rhodamine B (ROD) were prepared by SEE; the beads showed a solvent residue lower than 10 ppm and encapsulated the fluorochrome with an efficiency of 90%. SuperLip uses dCO2 to enhance lipid/ethanol/water mixing and to promote the ethanol extraction from liposome suspension. In this case, phosphatidyl-choline (PC) vesicles with a mean size of 0.2 ±â€¯0.05 µm and loaded with Fluorescein Iso-ThioCyanate (FITC) at 8 µg/mgPC were prepared; small unilamellar structure was observed for all the vesicles with FITC encapsulation efficiency of 80%. Ethanol residue of 50 ppm was measured in all the liposome suspensions. The bioavailability of microbeads and nanoliposomes was assessed through incubation with human monocytes previously isolated from healthy donors' blood. A specifically optimized protocol that allowed their quenching on the cell surface was developed to monitor by flow cytometer assay only the cell population that effectively internalized the carriers. When microbeads were tested, the percentage of alive internalizing monocytes was of about 30%. An internalization of 96.1 ±â€¯21% was, instead, obtained at dosage of 0.1 mg/mL for nanoliposomes. In this last case, monocytes showed a vitality of almost 100% after vesicles internalization at all the concentrations studied; on the other hand, cell apoptosis progressively increased in a dose/response manner, after polymer microbeads phagocytosis. The proposed data suggested that dCO2 technologies can be reliably used to fabricate intracellular carriers.

Assessment of the triage system in a pediatric emergency department. A pilot study on critical codes.

INTRODUCTION: In Italy, triage involves assigning a priority color code to patients arriving at the hospital Emergency Department: red (very critical), yellow (moderately critical), green (not very critical), and white (not critical). METHODS: This study was aimed at assessing the triage system in the Emergency Department of "Giannina Gaslini" Children's Hospital in Genoa, Italy. The authors examined 130 triage forms assigning a yellow code in 2003, in order to determine whether they had been correctly filled in with regard to the detection of vital parameters, identification of main symptoms and color code assignment. RESULTS: Results showed that vital signs were recorded in 94% of patients, main symptoms were identified in 97%, and a yellow code was assigned according to hospital guidelines in 84%. The percentage of underestimation (3.2%) was higher than that reported in the literature (2%). CONCLUSIONS: The study shows the need to improve compliance with the guidelines and to evaluate green and white codes.

Return visits to the Paediatric Emergency Department: first analysis in Italy.

Return visits to the emergency room have come under scrutiny with a view to identifying the reasons for these events. The aim of the study was to estimate the incidence of return visits to emergency room and to compare this with data from other countries, with a view to proposing a method of monitoring this parameter nationwide. Ours is the first Italian study to report the incidence of return visits to the ER and to analyse the factors correlated with this phenomenon. The incidence of return visits within 72 hours of the first visit proved to be 2.5%. Statistical analysis revealed a significant difference in the number of return visits between patients under 1 year of age and those older than 1 year. Our future objective is to re-analyse recent case-records on the basis of the indicators identified, with a view to assessing the quality of the service.

[Headache in a pediatric emergency department]. / La cefalea in pronto soccorso pediatrico.

INTRODUCTION: Headache, a very frequent symptom in pediatrics, can severely affect the child and his family's life quality, representing an important reason of access to a Pediatric Emergency Department. From a clinical point of view, it is useful to subdivide headaches in primary and secondary ones. As far as the primary ones are concerned, the common migraine without aura is recognised as the most frequent in the child, while the most recurrent among the second ones are due to infective processes, and they represent 57% of the patients admitted to ED for headache with acute onset. MATERIALS AND METHODS: We analyzed data collected from June 2000 to December 2006, at the Pediatric Emergency Department of Institute "G. Gaslini" Genoa, concerning the admissions of patients with headache, with particular attention to the necessity of coming up with a clinical and diagnostical path. RESULTS: During the study, there have been 228.255 admissions, 2.214 of which with a diagnosis of discharge from ED of headache (55% males, 45% females). After triage, 14,3% has been evaluated as white code, 74,3% as green one, 10,8% as yellow one and 0,6% as red code. Final outcome of these patients has been hospitalization for 38%, OBI for 8%, home or ambulatory control for 54%. CONCLUSIONS: The accesses to ED for headache are increasing. Better information of the family is needed, with coordination among territorial structures and clinic management in ED.

Pressure tuning of light-induced superconductivity in K3C60.

Optical excitation at terahertz frequencies has emerged as an effective means to dynamically manipulate complex materials. In the molecular solid K3C60, short mid-infrared pulses transform the high-temperature metal into a non-equilibrium state with the optical properties of a superconductor. Here we tune this effect with hydrostatic pressure and find that the superconducting-like features gradually disappear at around 0.3 GPa. Reduction with pressure underscores the similarity with the equilibrium superconducting phase of K3C60, in which a larger electronic bandwidth induced by pressure is also detrimental for pairing. Crucially, our observation excludes alternative interpretations based on a high-mobility metallic phase. The pressure dependence also suggests that transient, incipient superconductivity occurs far above the 150 K hypothesised previously, and rather extends all the way to room temperature.

Coherent THz Emission Enhanced by Coherent Synchrotron Radiation Wakefield.

We demonstrate that emission of coherent transition radiation by a ∼1 GeV energy-electron beam passing through an Al foil is enhanced in intensity and extended in frequency spectral range, by the energy correlation established along the beam by coherent synchrotron radiation wakefield, in the presence of a proper electron optics in the beam delivery system. Analytical and numerical models, based on experimental electron beam parameters collected at the FERMI free electron laser (FEL), predict transition radiation with two intensity peaks at ∼0.3 THz and ∼1.5 THz, and extending up to 8.5 THz with intensity above 20 dB w.r.t. the main peak. Up to 80-µJ pulse energy integrated over the full bandwidth is expected at the source, and in agreement with experimental pulse energy measurements. By virtue of its implementation in an FEL beam dump line, this work promises dissemination of user-oriented multi-THz beamlines parasitic and self-synchronized to EUV and x-ray FELs.

Breast cancer in southern Brazil: association with past dietary intake.

OBJECTIVE: To determine possible associations between the risk of breast cancer in Brazilian women and demographic, social and economical variables, and past dietary intake. METHODS: A case-control study was conducted in Joinville, Santa Catarina, Brazil, between june and november 2003 involving a group of 33 women recently diagnosed with breast cancer and a control group of 33 healthy women volunteers. Personal details, health history and past dietary intake were obtained via questionnaires and interviews. Data between groups were compared using chi2, Fisher, and Student's t test, whilst associations were evaluated using a non-conditional logistic regression method and odds ratio (OR). RESULTS: Statistically significant differences between the two groups were revealed with respect to age distribution (P = 0.007), family income level (P = 0.02), educational level (P < 0.0001) and attainment of menopause (P < 0.0001). After adjustment, with regard to family income level, of the data concerning past dietary intake, the consumption of pig lard (OR = 6.32) and fatty red meat (OR = 3.48) were found to be associated with an increase in the risk of breast cancer. The regular ingestion of apples (OR = 0.30), watermelons (OR = 0.31), tomatoes (OR = 0.16), plain cakes (OR = 0.30) and desserts (OR = 0.20) afforded some degree of protection against the development of the disease. CONCLUSIONS: Age (> 45 years), low family income (< $520/month), poor educational level (primary school level or lower) and past regular consumption of pork fat and fatty meat may be factors associated with an increased risk of breast cancer.

Toxic epidermal necrolysis in a child. A case report and review of the literature.

A 7-year-old boy with toxic epidermal necrolysis (TEN) is reported. The patient was treated with intravenous fluids, antibiotics, steroids, and immunoglobulins. Moreover, total parenteral nutrition was required for 4 days. He gradually improved and was discharged in a good clinical condition. Appropriate treatment for TEN is still controversial. Larger study are required to address this issue.

Ferritin-supported lipid bilayers for triggering the endothelial cell response.

Hybrid nanoassemblies of ferritin and silica-supported lipid bilayers (ferritin-SLBs) have been prepared and tested for the adhesion, spreading and proliferation of retinal microvascular endothelial cells (ECs). Lipid membranes with varying surface charge were obtained by mixing cationic 1-palmitoyl-2-oleoyl-sn-glycero-3-ethylphosphocholine (POEPC) with zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at increasing POPC/POEPC ratios. The supported bilayer formation and their subsequent interaction processes with ferritin were studied at the pH of 7.4 at different protein concentrations, by using the quartz crystal microbalance with dissipation monitoring and by atomic force microscopy. Both kinetics and viscoelastic parameters of the protein-lipid membrane interface were scrutinized, as well as surface coverage. Phase-contrast optical microscopy analyses of the ferritin-SLBs substrates after their interaction with endothelial cells evidenced the highest cell adhesion (2-4h of incubation time) and proliferation (from 24h to 5 days) for the membranes of POPC/POEPC (75:25 ratio). Moreover, ferritin increased both cell adhesion and proliferation in comparison to control glass (respectively 1.5- and 1.75-fold) as well as proliferation in comparison to bare POPC/POEPC (95:5 ratio) (2 fold). Results are very promising in the goal of modulating the endothelial cell response through the interplay of viscoelastic/charge properties of the solid-supported membranes and the SLB-conditioned ferritin activity.