Second harmonic generation in AlGaAs photonic wires using low power continuous wave light

We report modal phase matched (MPM) second harmonic generation (SHG) in high-index contrast AlGaAs sub-micron ridge waveguides, by way of sub-mW continuous wave powers at telecommunication wavelengths. We achieve an experimental normalized conversion efficiency of ~14%/W/cm2, obtained through a careful sub-wavelength design supporting both the phase matching requirement and a significant overlap efficiency. Furthermore, the weak anomalous dispersion, robust fabrication technology and possible geometrical and thermal tuning of the device functionality enable a fully integrated multi-functional chip for several critical areas in telecommunications, including wavelength (time) division multiplexing and quantum entanglement.

Thermal stability of corrugated epitaxial graphene grown on Re(0001)

We report on a novel approach to determine the relationship between the corrugation and the thermal stability of epitaxial graphene grown on a strongly interacting substrate. According to our density functional theory calculations, the C single layer grown on Re(0001) is strongly corrugated, with a buckling of 1.6 Å, yielding a simulated C 1s core level spectrum which is in excellent agreement with the experimental one. We found that corrugation is closely knit with the thermal stability of the C network: C-C bond breaking is favored in the strongly buckled regions of the moiré cell, though it requires the presence of diffusing graphene layer vacancies.

Multipurpose modular experimental station for the DiProI beamline of Fermi@Elettra free electron laser

We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011.

Angiogenic cells, macroparticles and RNA transcripts in laparoscopic vs open surgery for colorectal cancer

BACKGROUND

Angiogenesis is crucial for tissue repair and cancer progression. We investigated a panel of angiogenic cells, macroparticles and RNA transcripts before, during and after laparoscopic colectomy or open colectomy for colorectal cancer.

RESULTS

Viable and apoptotic circulating endothelial cells were significantly increased after open but not after laparoscopic colectomy (p < 0.01). A significant decrease of circulating mRNA coding for VEGFR-C and D and PDGFR-β was found after laparoscopic but not after open colectomy.

METHODS

A total of 24 patients were enrolled. Viable and apoptotic circulating endothelial cells, progenitors and macroparticles were evaluated by flow cytometry. The number of copies of angiogenesis-related RNA transcripts we reevaluated by quantitative PCR.

CONCLUSION

Open, but not laparoscopic colectomy, was associated with a significant post-operative increase in circulating endothelial cells, either apoptotic (likely due to surgery-related vascular damage) and viable (likely representing vascular remodeling). Circulating RNA copies coding for some angiogenic genes were significantly decreased after laparoscopic colectomy likely because of the removal of the tumor lesion. This decrease was not observed after open colectomy,were a more pronounced wave of angiogenesis related to wound healing was expected. These results indicate a relevant wave of angiogenesis-related cells and transcripts after open but not after laparoscopic colectomy.

Corrugation in exfoliated graphene: an electron microscopy and diffraction study

Low-energy electron microscopy and microprobe diffraction are used to image and characterize corrugation in SiO(2)-supported and suspended exfoliated graphene at nanometer length scales. Diffraction line-shape analysis reveals quantitative differences in surface roughness on length scales below 20 nm which depend on film thickness and interaction with the substrate. Corrugation decreases with increasing film thickness, reflecting the increased stiffness of multilayer films. Specifically, single-layer graphene shows a markedly larger short-range roughness than multilayer graphene. Due to the absence of interactions with the substrate, suspended graphene displays a smoother morphology and texture than supported graphene. A specific feature of suspended single-layer films is the dependence of corrugation on both adsorbate load and temperature, which is manifested by variations in the diffraction line shape. The effects of both intrinsic and extrinsic corrugation factors are discussed.

Domain-wall depinning assisted by pure spin currents

We study the depinning of domain walls by pure diffusive spin currents in a nonlocal spin valve structure based on two ferromagnetic Permalloy elements with copper as the nonmagnetic spin conduit. The injected spin current is absorbed by the second Permalloy structure with a domain wall, and from the dependence of the wall depinning field on the spin current density we find an efficiency of 6×10{-14}  T/(A/m{2}), which is more than an order of magnitude larger than for conventional current induced domain-wall motion. Theoretically we find that this high efficiency arises from the surface torques exerted by the absorbed spin current that lead to efficient depinning.

Serial assessment of amniotic fluid index in uncomplicated term pregnancies: prognostic value of amniotic fluid reduction

OBJECTIVE

Assessment of amniotic fluid volume in association with a non-stress test is a commonly used method to monitor fetal well-being in high-risk pregnancies. The aims of our study were to determine whether oligohydramnios and the trend in amniotic fluid volume have prognostic significance in low-risk pregnancies between 40.0 and 41.6 weeks' gestation.

METHODS

Between January 1997 and December 2000, all uncomplicated gestations with a singleton non-anomalous fetus reaching 40.0 weeks' gestation underwent semi-weekly monitoring of amniotic fluid index (AFI) until delivery. Oligohydramnios was defined as an AFI of < or = 5 cm. Changes in AFI were expressed as centimeters per day, and were calculated as: [(last AFI before delivery minus first AFI at 40.0 weeks) / interval in days between the two scans]. Adverse outcome was considered the occurrence of 5-min Apgar score < 7; umbilical artery pH < 7.0; Cesarean section for fetal distress; or fetal death. Comparisons between the groups with favorable and adverse outcomes was performed with chi(2) or Fisher's exact test for categorical variables, and Student's t test for continuous variables. A two-tailed p value < 0.05 was considered significant.

RESULTS

A total of 3050 women met the study criteria, and underwent a median number of two (range 1-7) sonographic assessments of AFI after 40.0 weeks, with oligohydramnios detected in 341 women. In 1466 women at least two serial AFI determinations were obtained, allowing computation of an AFI trend. Gestations resulting in adverse perinatal outcome (n = 167, 5.5%) had a significantly higher rate of oligohydramnios (33/167, 19.8% vs. 308/2883, 10.7%, p = 0.001), but a similar rate of reduction in AFI ( -0.65 +/- 0.64 vs. - 0.66 +/- 0.66 cm/day; p = 0.85) than those with favorable outcome. The difference in rate of reduction of AFI between the two groups was not significant, even in the subset of gestations that developed oligohydramnios ( -1.08 +/- 0.87 vs. -1.26 +/- 0.89 cm/day; p = 0.27).

CONCLUSION

A sonographic diagnosis of oligohydramnios carries an increased risk of adverse perinatal outcome, even in low-risk pregnancies after 40 weeks. The trend in amniotic fluid volume reduction does not seem to have prognostic significance.

Analysis of the optical properties of wire antennas with displaced terminals

An analysis of the peculiar features of optical wire antennas with displaced terminals is presented. Full-wave simulations and a semianalytical technique based on Pocklington's equation are used in order to systematically study the behavior of input impedance and field enhancement at the antenna terminals when the feed-gap region is shifted with respect to the center of the wire. A simple analytical model based on the evaluation of the effective wavelength of the propagating surface wave is also suggested for the interpretation of the results.

Optical filter based on two coupled PhC GaAs-membranes

We demonstrate an ultracompact optical filter based on two coupled high-index contrast GaAs photonic crystal (PhC) membranes. The PhC membranes consist of a square lattice of air holes and behave as a Fabry-Perot cavity whose reflectivity and transmissivity depend on the air gap between the two membranes. The normal-incidence reflectance measurements and the numerical simulation of reflection spectra show a high sensitivity to the geometrical parameters, such as the distance between the slabs, whose control would make the device suitable for a new class of tunable optical filters.

The electron density decay length effect on surface reactivity

The correlation between the thickness-dependent oxidation rate of ultrathin Al films on W(110) and the quantum-well states (QWS) resulting from electron confinement in the Al film has been explored by combined x-ray photoemission electron microscopy (XPEEM), low energy electron microscopy (LEEM), and first-principles calculations. Hybridization with substrate electronic states is observed to alter the film electronic structure, strongly modifying the electron density decay length in vacuum. The decay length, rather than the density of states at the Fermi energy, is found to dominate the observed reactivity trends.

Phase Ib study of weekly mammalian target of rapamycin inhibitor ridaforolimus (AP23573; MK-8669) with weekly paclitaxel

BACKGROUND

The additive cytotoxicity in vitro prompted a clinical study evaluating the non-prodrug rapamycin analogue ridaforolimus (AP23573; MK-8669; formerly deforolimus) administered i.v. combined with paclitaxel (PTX; Taxol).

MATERIALS AND METHODS

Patients with taxane-sensitive solid tumors were eligible. The main dose escalation foresaw 50% ridaforolimus increments from 25 mg with a fixed PTX dose of 80 mg/m(2), both given weekly 3 weeks in a 4-week cycle. Collateral levels with a lower dose of either drug were planned upon achievement of the maximum tolerated dose in the main escalation. Pharmacodynamic studies in plasma, peripheral blood mononuclear cells (PBMCs) and skin biopsies and pharmacokinetic (PK) interaction studies at cycles 1 and 2 were carried out.

RESULTS

Two recommended doses were determined: 37.5 mg ridaforolimus/60 mg/m(2) PTX and 12.5 mg/80 mg/m(2). Most frequent toxic effects were mouth sores (79%), anemia (79%), fatigue (59%), neutropenia (55%) and dermatitis (48%). Two partial responses were observed in pharyngeal squamous cell and pancreatic carcinoma. Eight patients achieved stable disease > or =4 months. No drug interaction emerged from PK studies. Decrease of eukaryotic initiation factor 4E-binding protein1 (4E-BP1) phosphorylation was shown in PBMCs. Similar inhibition of phosphorylation of 4E-BP1 and mitogen-activated protein kinase was present in reparative epidermis and vascular tissues, respectively.

CONCLUSION

Potential antiangiogenic effects and encouraging antitumor activity justify further development of the combination.

Modeling of enhanced field confinement and scattering by optical wire antennas

We describe the application of full-wave and semi-analytical numerical tools for the modeling of optical wire antennas, with the aim of providing novel guidelines for analysis and design. The concept of antenna impedance at optical frequencies is reviewed by means of finite-element simulations, whereas a surface-impedance integral equation is derived in order to perform an accurate and efficient calculation of the current distribution, and thereby to determine the equivalent-circuit parameters. These are introduced into simple circuits models, directly borrowed from radio frequency, which are applied in order to model the phenomena of enhanced field confinement at the feed gap and light scattering by optical antennas illuminated by plane waves.

Are ultrasonographic myoma characteristics associated with blood loss at delivery?

OBJECTIVES

The presence of myomas in pregnancy is associated with greater blood loss at delivery. The aim of this study was to evaluate whether the sonographic characteristics of myomas can predict blood loss at delivery in women with large myomas.

METHODS

Among women who underwent second-trimester ultrasound screening at our department between January 1996 and December 2004, 251 had at least one myoma with a mean diameter > or = 5 cm. Number of myomas (single vs. multiple), maximum diameter of the largest myoma, sum of the maximum diameter of each myoma, change in size of myomas between first and last scan, and location in relation to the placenta and to the presenting part of the fetus (above or below) were analyzed in relation to blood loss at delivery and severe postpartum hemorrhage (> or = 1000 mL).

RESULTS

Multivariate analysis showed that the presence of multiple myomas was the only parameter independently associated with amount of blood loss at delivery (P = 0.003). The association between the presence of multiple myomas and severe postpartum hemorrhage was of borderline significance for the statistical power of this study (P = 0.08).

CONCLUSIONS

In women with large myomas, the presence of multiple tumors is independently associated with heavier blood loss at delivery but not with postpartum hemorrhage of > or = 1000 mL.

Clinical and pharmacological phase I evaluation of Exherin (ADH-1), a selective anti-N-cadherin peptide in patients with N-cadherin-expressing solid tumours

BACKGROUND

Upregulation of N-cadherin promotes dysregulated cell growth, motility, invasiveness, plus maintenance of vascular stability and is associated with cancer progression in several human tumour types. N-cadherin is expressed also on tumour cells and the anti-N-cadherin cyclic pentapeptide ADH-1, tested in the present study, can exert a direct antitumour effect.

PATIENTS AND METHODS

Adult patients with advanced solid malignancies expressing N-cadherin on tumour biopsies carried out in the previous 12 months received escalating i.v. doses of ADH-1 given weekly (initially for 3 of 4 weeks, then every week). Plasma pharmacokinetics (PK) was studied at cycle 1. Blood flow changes were assessed after first dosing in all patients treated in the initial regimen.

RESULTS

In all, 129 patients were screened, 65 (50%) were N-cadherin positive, and 30 were enrolled. The doses ranged from 150 to 2400 mg/m(2); no maximum tolerated dose was reached. Treatment was well tolerated with asthenia as the most frequent adverse event. Two patients with ovarian cancer showed prolonged disease stabilisation while one patient with fallopian tube carcinoma achieved a mixed response. PK was linear in the range of doses tested.

CONCLUSION

ADH-1 is the first anti-N-cadherin compound tested in humans. In N-cadherin-positive patients, ADH-1 showed an acceptable toxicity profile, linear PK and hints of antitumour activity in gynaecological cancers.

Mass transport of alkali metal with pulses in a surface reaction

It is shown that the pulses which develop in the NO+H2 reaction on an alkali promoted Rh(110) surface reaction can transport alkali metal. This leads to the accumulation of a substantial alkali-metal concentration in the collision area of pulse trains. Realistic simulations revealed that the effect is due to the strong energetic interactions of the alkali metal with coadsorbates, i.e., the attractive interaction with coadsorbed oxygen and the effectively repulsive interaction with coadsorbed nitrogen.

Spectromicroscopy for addressing the surface and electron transport properties of individual 1-d nanostructures and their networks

Understanding size/dimensionality-dependent phenomena and processes relevant to chemical sensing and catalysis requires analytical methods with high surface sensitivity, which can exploit the structure and composition of nanomaterials at their natural length scales and working conditions. In the present study, we explored the potentials and complementary capabilities of several surface-sensitive microscopy approaches to shed light on the properties of individual SnO(2) nanowires and their networks. Our results demonstrate the unique opportunities provided by synchrotron-based photoelectron microscopies for surface-sensitive structural and chemical analysis, including in situ characterization of electron transport properties of a nanostructure wired as an active element in chemiresistor devices.

Stress induced stripe formation in Pd/W(110)

A stress-induced stripe phase of submonolayer Pd on W(110) is observed by low-energy electron microscopy. The temperature dependence of the pattern is explained by the change both in the boundary free energy and elastic relaxation energy due to the increasing boundary width. The stripes are shown to disorder when the correlation length of the condensed phase becomes comparable to its period, while the condensate to lattice-gas transition takes place at a higher temperature, as revealed by low-energy electron diffraction.

Generation of ultrashort coherent vacuum ultraviolet pulses using electron storage rings: a new bright light source for experiments

We demonstrate for the first time that seeded harmonic generation on electron storage rings can produce coherent optical pulses in the vacuum ultraviolet spectral range. The experiment is performed at Elettra, where coherent pulses are generated at 132 nm, with a duration of about 100 fs. The light source has a repetition rate of 1 kHz and adjustable polarization; it is very bright, with a peak power several orders of magnitude above that of spontaneous synchrotron radiation. Owing to high stability, the source is used in a test photoemission electron microscopy experiment. We anticipate that seeded harmonic generation on storage rings can lead to unprecedented developments in time-resolved femtosecond spectroscopy and microscopy.

suPAR, a soluble form of urokinase plasminogen activator receptor, inhibits human prostate cancer cell growth and invasion

Urokinase-type plasminogen activator (uPA) and its specific membrane receptor (uPAR) control extracellular matrix proteolysis, cell migration, invasion and cell growth in several cancers. The uPAR released from human cancers is detected in blood as soluble uPAR (suPAR). No information is available on the mechanism(s) of action of suPAR on prostate cancer (PCa) cell growth and invasion. In order to clarify this issue, we tested the effect of a treatment with the human recombinant suPAR (comprising amino acids l-303) on the proliferation, migration and invasion of DU145 cells, a PCa cell line expressing a potent autocrine uPA-uPAR signalling system. The results indicate that suPAR significantly inhibits cell growth, promotes apoptosis and decreases both migration and Matrigel invasion of DU145 cells. The mechanism of action of suPAR seems to be linked to a decrease of ERK and FAK activation. Cleavage of suPAR by chymotripsin reverses these effects. When added to the uPA-negative LNCaP cells, suPAR was ineffective; on the contrary, when LNCaP cells were cultured on fibronectin-coated plates in order to stimulate uPA expression, suPAR significantly decreased cell proliferation. In conclusion, our data suggest that suPAR can function as a potent molecule scavenger for uPA in human PCa cells characterized by high levels of uPA/uPAR as in DU145 cells, while it is ineffective in uPA-deficient LNCaP cells. The molecular mechanism(s) through which suPAR participates in the control of PCa progression may bear relevance for the long-term goal to identify new therapeutic targets aimed at silencing tumours in vivo.

Relationship between nonadiabaticity and damping in permalloy studied by current induced spin structure transformations

By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter beta does not equal the damping alpha, in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core.

Gold-catalyzed oxide nanopatterns for the directed assembly of Ge island arrays on Si

The heteroepitaxial growth of Ge on Au-patterned Si(001) is investigated using in situ spectromicroscopy. Patterning of a hydrogen-terminated Si surface with a square array of Au dots followed by brief exposure to air leads to the spontaneous, local oxidation of Si. The resulting oxide nanopattern limits the surface migration of Au during annealing up to 600 degrees C, resulting in complete preservation of the Au pattern. Subsequent deposition of Ge induces a redistribution of Au across the surface even as the oxide nanopattern persists. As a result, the oxide pattern drives the growth of Ge islands into an ordered assembly, while Au decorates the surfaces of the Ge islands and modifies their shape.

Maximum-exponent scaling behavior of optical second-harmonic generation in finite multilayer photonic crystals

Scaling laws of second-harmonic generation (SHG) in nonlinear Bragg stacks (or finite one-dimensional photonic crystals) as a function of the number N of periods are explored. While it is known that SHG scales like the sixth power of N when phase matching is achieved, we find maximal scaling like the eighth power of N under appropriate non-phase-matching conditions with the pump and harmonic waves being resonant with band-edge states. In this framework we introduce the concept of self-adaptive coherence length that scales with the system length. An analytical treatment based on coupled-mode equations clarifies the conditions for obtaining different scaling laws as a function of filling factor in the photonic gap map.

Phase 1b study defining the optimal dosing combinations of the mTOR inhibitor AP23573 and Paclitaxel (PTX)

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Background: AP23573 is a novel mTOR inhibitor with demonstrated anti-tumor activity in clinical trials. In vitro, AP23573 exhibits at least additive anti-proliferative activity in combination with a variety of agents including taxanes. This trial studied the combination of AP23573 and paclitaxel (PTX) in patients with advanced solid tumors. Methods: This was a modified, sequential (3+3) dose finding study with starting doses of 25 mg AP23573 i.v. and 80 mg/m2 PTX i.v. as Dose Level 1 (DL1) on days 1, 8 and 15 of a 28 day cycle. Doses of either drug were adjusted in successive cohorts. Blood samples and skin biopsies were collected for pharmacokinetic (PK) and pharmacodynamic (PD) studies. Dose limiting toxicity definitions included neutrophils <500/μL; thrombocytopenia = Grade 3 (CTC), any non- hematologic toxicities = Grade 2; missing 2 consecutive doses due to any toxicity. For PK and PD analysis, AP23573 and PTX were administered one day apart at the start of Cycle 1, reversing the sequence at Day 8. Results: Enrollment is complete and 29 patients with a variety of tumors (sarcoma, pancreatic, H&N, melanoma, thymoma) have been treated. Grade 3 thrombocytopenia and Grade 2 mouth sores were seen at DL1 as well as missed doses due to moderate (Grade 2) neutropenia. Adverse events include mouth sores and fatigue which were mild and reversible. Available PK data for AP23573 and PTX suggest no interaction. PD analysis in peripheral blood mononuclear cells demonstrates no interference by PTX on mTOR inhibition by AP23573. PD data in skin biopsies are forthcoming. Both 12.5 mg AP23573/80mg/m2 PTX and 37.5mg AP23573/60mg/m2 PTX are maximal dose combinations that appear to be well tolerated. Activity has been observed at multiple AP23573 mg/PTX mg/m2 dose levels (25/60, 12.5/80, 25/80). Five patients have been on study for >4 cycles, including 2 patients with partial responses (H&N and pancreatic). Conclusions: Combined therapy with AP23573 and PTX is safe. It is notable that evidence of anti-tumor activity was observed at modest doses of each drug when in combination. Combinations of these agents at both doses cited would be recommended for evaluation in trials examining efficacy in specific tumors.

No significant financial relationships to disclose.

Morphology and composition of InAs/GaAs quantum dots

Surface compositional maps of self-organized InAs/GaAs quantum dots were obtained with laterally resolved photoemission spectroscopy. We found a surface In concentration of about 0.85 at the center of the islands which decreases to 0.75 on the wetting layer. Comparison with concentration values found in the core of similar dots suggests a strong In segregation on the topmost surface layers of the dots and on the surrounding wetting layer. Furthermore, the morphological properties of the dots such as size and density have been measured with plan-view transmission electron microscopy and low energy electron microscopy.

Pentraxin 3 in plasma and vaginal fluid in women with preterm delivery

OBJECTIVE To investigate the role of pentraxin 3 (PTX3), an acute-phase protein produced by cells of innate immunity in response to inflammatory signals, in spontaneous preterm delivery (PTD). DESIGN Cohort study. SETTING Department of Obstetrics and Gynecology of the University of Milano-Bicocca. POPULATION Forty-six pregnant women with preterm rupture of membranes (n=33) or preterm labour with intact membranes (n=13) delivering at <34 weeks of gestation and 34 women with uncomplicated pregnancies (control group). METHODS We compared plasma and vaginal PTX3 levels between study group and controls, and in women with versus women without clinical or histologic evidence of intrauterine infection using statistical analysis. MAIN OUTCOME MEASURES Peak PTX3 concentration. RESULTS Peak PTX3 concentration in plasma samples of study group was significantly higher than that in controls (1175, 0-9630 versus 650, 0-1450 pg/ml; P=0.0003) but not in vaginal swabs (1660, 0-6604 versus 457, 0-4649 pg/ml; P=0.386). PTX3 levels in plasma were significantly higher in women with placenta vasculopathy compared with that in women with no placental lesions (2910, 0-9630 versus 636, 0-5692 pg/ml; P=0.04). Peak plasma and vaginal PTX3 concentrations were not significantly different in women with versus women without intrauterine infection (1168, 0-7110 versus 845, 0-9630 pg/ml, P=0.34 and 1975, 471-6604 versus 1919, 0-4150 pg/ml, P=0.38, respectively). CONCLUSIONS Spontaneous PTD is associated with a significant increase of maternal plasma concentrations of PTX3. PTX3 seems to be a marker of placenta vasculopathy rather than intrauterine infection.

Alignment of Ge nanoislands on Si(111) by Ga-induced substrate self-patterning

A novel mechanism is described which enables the selective formation of three-dimensional Ge islands. Submonolayer adsorption of Ga on Si(111) at high temperature leads to a self-organized two-dimensional pattern formation by separation of the 7 x 7 substrate and Ga/Si(111)-(square root[3] x square root[3])-R30 degrees domains. The latter evolve at step edges and domain boundaries of the initial substrate reconstruction. Subsequent Ge deposition results in the growth of 3D islands which are aligned at the boundaries between bare and Ga-covered domains. This result is explained in terms of preferential nucleation conditions due to a modulation of the surface chemical potential.

Imaging with Chemical Analysis: Adsorbed Structures Formed during Surface Chemical Reactions

Imaging surfaces and interfaces with structural and chemical specificity has been essential for understanding a variety of phenomena occurring in adsorbed layers during surface chemical reactions. A recent achievement of chemical imaging with spectroscopic analysis is the experimental proof of theoretically predicted spontaneous formation of regular patterns of metal adatoms during surface chemical reactions. An attractive feature of this finding is that the reaction rate and adlayer coverage can be employed to precisely control the morphology of the structures. The mechanisms of these self-organisation phenomena, driven by the interplay between energetic principles and kinetics, opens a conceptually novel route to creating a wide range of surface-supported functional structures at the micro- and nanometre length scales.

Enhanced third-order nonlinear effects in optical AlGaAs nanowires

We report the first observation of enhanced third-order nonlinear effects in AlGaAs nanowires. AlGaAs nanowaveguides with widths varying from 100 to 600nm were fabricated and characterized. Nonlinear phase shifts of approximately pi were experimentally observed at 1.55mum with peak powers of 30-40W in 600mum long, 550nm wide guides.

Formation of Regular Surface-Supported Mesostructures with Periodicity Controlled by Chemical Reaction Rate

We report a LEEM and XPEEM study of the formation of a variety of stationary two-dimensional metallic and oxygen structures in Au and Au + Pd adlayers on Rh(110) during water formation reaction. They result from chemically frozen spinodal decomposition and are created, preserved, or reversibly modified by tuning the reaction conditions. The wavelength of lamellar structures obtained at intermediate metal coverage is found to obey a power scaling law with respect to the reaction rate.

Molecular Basis of Kindler Syndrome in Italy: Novel and Recurrent Alu/Alu Recombination, Splice Site, Nonsense, and Frameshift Mutations in the KIND1 Gene

Kindler syndrome (KS) is a rare autosomal recessive disorder characterized by skin blistering in childhood followed by photosensitivity and progressive poikiloderma. Most cases of KS result from mutations in the KIND1 gene encoding kindlin-1, a component of focal adhesions in keratinocytes. Here, we report novel and recurrent KIND1 gene mutations in nine unrelated Italian KS individuals. A novel genomic deletion of approximately 3.9 kb was identified in four patients originating from the same Italian region. This mutation deletes exons 10 and 11 from the KIND1 mRNA leading to a truncated kindlin-1. The deletion breakpoint was embedded in AluSx repeats, specifically in identical 30-bp sequences, suggesting Alu-mediated homologous recombination as the pathogenic mechanism. KIND1 haplotype analysis demonstrated that patients with this large deletion were ancestrally related. Five additional mutations were disclosed, two of which were novel. To date, four recurrent mutations have been identified in Italian patients accounting for approximately approximately 75% of KS alleles in this population. The abundance of repetitive elements in intronic regions of KIND1, together with the identification of a large deletion, suggests that genomic rearrangements could be responsible for a significant proportion of KS cases. This finding has implications for optimal KIND1 mutational screening in KS individuals.

Pharmacokinetic study of paclitaxel and gefitinib in combination

13123

Background: Both gefitinib and paclitaxel are metabolized by CYP3A4, thus co-administration may result in a pharmacokinetic interaction (Miller V.A. et al. JCO 2003, 21:2094–2100). Paclitaxel is formulated in Cremophor EL (crEL), which also has the potential for pharmacokinetic interactions by either altering protein binding or inhibition of P-glycoprotein transporter systems (Gelderblom H. et al. EJC 2001, 37:1590–1598). Gefitinib is a high extraction ratio drug so changes in protein binding are not a concern, but inhibition of P-glycoprotein transporter systems could change gefitinib’s absorption profile. Methods: In a Phase II study, 17 patients (pts) with metastatic breast cancer received paclitaxel (100 mg/m2 on days 8, 15 q21) with gefitinib (250 mg daily, from day 1 to day 15). Blood samples were collected to measure plasma concentrations of gefitinib on days 7, 8, and 15 from six pts at pre-dose and at 3, 7 and 25 hours after gefitinib administration. The AUC at steady-state (AUCss) was calculated by the linear trapezoidal rule using WinNonlin and the minimum concentration at steady-state (Css, min) was taken directly from the data. Results: The effect of paclitaxel or crEL on the exposure to gefitinib was assessed by comparing the AUCss and Css,min on days 8 and 15 in the presence of paclitaxel to those on day 7 when gefitinib was alone. The geometric mean AUCss increased by 30 to 42% and Css,min by 28 to 58% in the presence of paclitaxel. Individual ratios of days 8 and 15 to day 7 also showed a trend to be greater than 1.0, further indicating an increase in exposure to gefitinib in the presence of paclitaxel. Conclusions: Steady state exposure to gefitinib increased by about 30 to 40% in the presence of paclitaxel. As the increase on day 15 was similar to that on day 8, the effect of paclitaxel appears to be transient, and would be unlikely to affect the safety profile of 250 mg gefitinib when in combination with paclitaxel compared to gefitinib monotherapy.

[Table: see text]

Discrete negative refraction in photonic crystal waveguide arrays

We report a systematic analysis of anomalous refractive effects at interfaces between two photonic crystal waveguide arrays. Discrete negative refraction can be easily predicted from the sign of the coupling coefficient between adjacent waveguides, regardless of handedness of propagation.

Diffusion dynamics during the nucleation and growth of Ge/Si nanostructures on Si(111)

We report a low energy electron microscopy study of the relation between self-organized Ge/Si(111)nanostructures and their local environment. By comparison with Monte Carlo simulations, three-dimensional islands are shown to display a substantial tendency towards self-ordering. This tendency may result from the diffusive nature of the nucleation processes. The size of individual nanostructures does not significantly correlate with the distance between neighboring islands. Thus energetic factors are thought to govern the competition among coexisting nanostructures to capture the deposited mass.

Chemical mapping of individual semiconductor nanostructures

We demonstrate experimentally the power of a novel analytical tool for X-ray spectromicroscopy. This provides a minimally intrusive elemental mapping of surfaces at the nanoscale and holds the promise of remarkable versatility. We have applied our procedure to the characterization of Ge(Si) islands on Si(111) substrates, with the aim of investigating the surface stoichiometry gradients and gaining insight into the intermixing dynamics. By identifying Si-richer edges with respect to the centers, we are able to associate alloying in these islands to surface transport processes.

Frequency tunable polarization and intermodal modulation instability in high birefringence holey fiber

We present an experimental analysis of polarization and intermodal noise-seeded parametric amplification, in which dispersion is phase matched by group velocity mismatch between either polarization or spatial modes in birefringent holey fiber with elliptical core composed of a triple defect. By injecting quasi-CW intense linearly polarized pump pulses either parallel or at 45 degrees with respect to the fiber polarization axes, we observed the simultaneous generation of polarization or intermodal modulation instability sidebands. Furthermore, by shifting the pump wavelength from 532 to 625 nm, we observed a shift of polarization sidebands from 3 to 8 THz, whereas intermodal sidebands shifted from 33 to 63 THz. These observations are in excellent agreement with the experimental characterization and theoretical estimates of phase and group velocities for the respective fiber modes.

Diffraction engineering in arrays of photonic crystal waveguides

Light propagation in uniform arrays of photonic crystal waveguides is studied. We demonstrate that, in stark contrast to the case of conventional waveguide arrays, diffraction can be tailored both in magnitude and sign by varying only the spacing between adjacent waveguides. Diffraction management in ultracompact arrays of straight photonic crystal waveguides is demonstrated by solving Maxwell's equations through the time-domain finite-element method.

Imaging of ferroelectric thin films by X-ray photoemission electron microscopy (XPEEM)

We performed X-ray photoemission electron microscopy (XPEEM) measurements at the Nanospectroscopy Beamline of the synchrotron light source ELETTRA, Trieste, Italy, to demonstrate the principal possibility of imaging ferroelectric thin films by low-energy photoelectrons. Due to the insulating properties of ferroelectric films, severe surface charging was the major experimental challenge to overcome. This was achieved by grounding an array of gold inter-digital electrodes (with 5 microm blank intervals between them) deposited on top of the films. The images taken with BaTiO(3) films revealed 50-100 nm-sized holes (material discontinuities) on the surface, an observation confirmed by high-resolution scanning electron microscopy (HRSEM). Finer details, e.g. a granular structure, which has been resolved with HRSEM, could not be observed in the XPEEM images. Our measurements indicate that despite some residual charging, a 50 nm lateral resolution can be achieved in XPEEM measurements with ferroelectric films.

Energetically Driven Reorganization of a Modified Catalytic Surface under Reaction Conditions

The compositional and structural rearrangements at the catalyst surface during chemical reactions are issues of great importance for understanding and modeling the catalytic processes. Low-energy electron microscopy and photoelectron spectromicroscopy studies of the real-space structure and composition of a Au-modified Rh(110) surface during water formation reveal reorganization processes due to Au mass transport triggered by the propagating reaction fronts. The temporal evolution of the surface reaction results in a 'patterned' surface consisting of separated Au-rich and Au-poor phases with different oxygen coverage, Rh surface structure, and reactivity. The experimental results are complemented by ab initio electronic-structure calculations of the O and Au adsorption phases, which demonstrate that the reorganization of the Au adlayer by the propagating reaction fronts is an energetically driven process. Our findings suggest that reaction-induced spatial inhomogeneity in the surface composition and structure is a common feature of metal catalysts modified with adatoms which become mobile under reaction conditions.