Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu.

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu.

Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

Hyperspectral imaging with a TWINS birefringent interferometer.

We introduce a high-performance hyperspectral camera based on the Fourier-transform approach, where the two delayed images are generated by the Translating-Wedge-Based Identical Pulses eNcoding System (TWINS) [Opt. Lett. 37, 3027 (2012)], a common-path birefringent interferometer that combines compactness, intrinsic interferometric delay precision, long-term stability and insensitivity to vibrations. In our imaging system, TWINS is employed as a time-scanning interferometer and generates high-contrast interferograms at the single-pixel level. The camera exhibits high throughput and provides hyperspectral images with spectral background level of -30dB and resolution of 3 THz in the visible spectral range. We show high-quality spectral measurements of absolute reflectance, fluorescence and transmission of artistic objects with various lateral sizes.

Versatile Control of

We demonstrate quantum control of ^{9}Be^{+} ions directly implemented by an optical frequency comb. Based on numerical simulations of the relevant processes in ^{9}Be^{+} for different magnetic field regimes, we demonstrate a wide applicability when controlling the comb's spectral properties. We introduce a novel technique for the selective and efficient generation of a spectrally tailored narrow-bandwidth optical frequency comb near 313 nm. We experimentally demonstrate internal state control and internal-motional state coupling of ^{9}Be^{+} ions implemented by stimulated-Raman manipulation using a spectrally optimized optical frequency comb. Our pulsed laser approach is a key enabling step for the implementation of quantum logic and quantum information experiments in Penning traps.

Towards VO2 monitoring: Validation of a heart rate based algorithm.

This article presents and validates a novel algorithm for the continuous monitoring of the VO2 during exercise. The algorithm relies on instantaneous HR measurements to provide a continuous estimation, and can be integrated in a wearable device (e.g., smartwatch, sensor patch). It can be customized by user's main anthropomorphic parameters and automatically learns from newly incoming data recalibrating itself if needed. The system is evaluated against a database of 14 healthy subjects performing various maximal endurance tests. The proposed method provides a VO2 estimation with average RMSE of 4.63 ml/kg/min.

Ultrafast spin-polarized electron dynamics in the unoccupied topological surface state of Bi2Se3.

The three-dimensional topological insulator Bi2Se3 presents two cone-like dispersive topological surface states centered at the [Formula: see text] point. One of them is unoccupied in equilibrium conditions and located 1.8 eV above the other one lying close to the Fermi level. In this work we employ time- and angle-resolved photoemission spectroscopy with circularly polarized pump photons to selectively track the spin dynamics of the empty topological states. We observe that spin-polarized electrons flow along the topological cone and recombine towards the unpolarized bulk states on a timescale of few tens of femtoseconds. This provides direct evidence of the capability to trigger a spin current with circularly polarized light.

Fourier transform spectroscopy in the vibrational fingerprint region with a birefringent interferometer.

We introduce a birefringent interferometer for Fourier transform (FT) spectroscopy in the mid-infrared, covering the vibrational fingerprint region (5-10 µm, 1000-2000 cm-1), which is crucial for molecular identification. Our interferometer employs the crystal calomel (Hg2Cl2), which combines high birefringence (ne-no≈0.55) with a broad transparency range (0.38-20 µm). We adopt a design based on birefringent wedges, which is simple and compact and guarantees excellent delay accuracy and long-term stability. We demonstrate FTIR spectroscopy, with a frequency resolution of 3 cm-1, as well as two-dimensional IR (2DIR) spectroscopy. Our setup can be extended to other spectroscopic modalities such as vibrational circular dichroism and step-scan FT spectroscopy.

Narrowband carrier-envelope phase stable mid-infrared pulses at wavelengths beyond 10 µm by chirped-pulse difference frequency generation.

We report on the generation of narrowband carrier-envelope phase stable mid-infrared (MIR) pulses between 10 and 15 µm. High pulse energies and narrow bandwidths are required for the selective nonlinear excitation of collective modes of matter that is not possible with current sources. We demonstrate bandwidths of <2% at 12.5 µm wavelength through difference frequency generation between two near-infrared (NIR) pulses, which are linearly chirped. We obtain a reduction in bandwidth by one order of magnitude, compared to schemes that make use of transform-limited NIR pulses. The wavelength of the narrowband MIR pulse can be tuned by changing the optical delay between the two chirped NIR pulses.

THz-Frequency Modulation of the Hubbard U in an Organic Mott Insulator.

We use midinfrared pulses with stable carrier-envelope phase offset to drive molecular vibrations in the charge transfer salt ET-F_{2}TCNQ, a prototypical one-dimensional Mott insulator. We find that the Mott gap, which is probed resonantly with 10 fs laser pulses, oscillates with the pump field. This observation reveals that molecular excitations can coherently perturb the electronic on-site interactions (Hubbard U) by changing the local orbital wave function. The gap oscillates at twice the frequency of the vibrational mode, indicating that the molecular distortions couple quadratically to the local charge density.

Late-presenting right congenital diaphragmatic hernia with severe hypotrophy of the right lobe of the liver.

INTRODUCTION: Congenital diaphragmatic hernia (CDH) presenting after 30 days of life is unusual and has a variant pattern of presentation. PRESENTATION OF CASE: We present a death case occurred to a 34-days-old infant. The infant arrived to our emergency department in cardiac arrest after having suffered from intermittent acute abdominal pain. Autopsy confirmed the presence of a right CDH, with herniation of the right lobe of the liver into the thorax. DISCUSSION: Most of the cases of CDH are diagnosed prenatally or in the neonatal period. However, some patients do not develop symptoms until after the neonatal period. The relevance of our case is the co-existence of right CDH and important hypotrophy of the right lobe of the liver. CONCLUSIONS: Evidence of this phenomenon represents an absolute novelty in the extant scientific literature. Even if rare, we suggest to suspect the presence of CDH in fetus with disparity in right and left liver lobe at prenatal ultrasound.

Intussusception in childhood: role of sonography on diagnosis and treatment.

OBJECTIVE: The aim of this study was to determine the role of ultrasound in the diagnosis and treatment of pediatric patients with acute abdominal pain caused by intussusceptions. MATERIALS AND METHODS: We performed a retrospective study of all pediatric patients with acute abdominal pain caused by intussusceptions and that underwent ultrasound examination at the emergency service of the Radiology Department between November 2007 and June 2013. The role of ultrasonography in the diagnosis of intussusceptions has been assessed by comparing the echographic presumptive diagnosis with the final diagnosis of discharge. Its importance in the treatment has been assessed by determining the value of ultrasound findings in the choice of the best treatment. RESULTS: The ultrasound examination was positive in 16/18 patients with a final diagnosis of intussusception. Some sonographic findings seemed to be able to predict the opportunity to resort to non-surgical therapeutic options like hydrostatic or pneumatic reduction of the intestinal segments invaginated. In our casuistry, five children presented characteristics typical of this subgroup and underwent barium enema which provided the reduction of the intestinal segments involved. The future challenge will be to perform non-surgical ultrasound-guided reductions to avoid the exposure of the infants to ionizing radiations. CONCLUSIONS: Ultrasonography is essential not only in the diagnosis, but also it adds important elements in the therapeutic choice and could play in the future an important role in non-surgical reduction of intestinal intussusceptions in pediatric patients.

A cross-sectional nationwide survey on esophageal atresia and tracheoesophageal fistula.

BACKGROUND: Our study aims at disclosing epidemiology and most relevant clinical features of esophageal atresia (EA) pointing to a model of multicentre collaboration. METHODS: A detailed questionnaire was sent to all Italian Units of pediatric surgery in order to collect data of patients born with EA between January and December 2012. The results were crosschecked by matching date and place of birth of the patients with those of diagnosis-related group provided by the Italian Ministry of Health (MOH). RESULTS: A total of 146 questionnaires were returned plus a further 32 patients reported in the MOH database. Basing on a total of 178 patients with EA born in Italy in 2012, the incidence of EA was calculated in 3.33 per 10,000 live births. Antenatal diagnosis was suspected in 29.5% patients. 55.5% showed associated anomalies. The most common type of EA was Gross type C (89%). Postoperative complications occurred in 37% of type C EA and 100% of type A EA. A 9.5% mortality rate was reported. CONCLUSIONS: This is the first Italian cross-sectional nationwide survey on EA. We can now develop shared guidelines and provide more reliable prognostic expectations for our patients.

Optical stark effects in j-aggregate-metal hybrid nanostructures exhibiting a strong exciton-surface-plasmon-polariton interaction.

We report on the observation of optical Stark effects in J-aggregate-metal hybrid nanostructures exhibiting strong exciton-surface-plasmon-polariton coupling. For redshifted nonresonant excitation, pump-probe spectra show short-lived dispersive line shapes of the exciton-surface-plasmon-polariton coupled modes caused by a pump-induced Stark shift of the polariton resonances. For larger coupling strengths, the sign of the Stark shift is reversed by a transient reduction in normal mode splitting. Our studies demonstrate an approach to coherently control and largely enhance optical Stark effects in strongly coupled hybrid systems. This may be useful for applications in ultrafast all-optical switching.

An innovative Yb-based ultrafast deep ultraviolet source for time-resolved photoemission experiments.

Time- and angle-resolved photoemission spectroscopy is a powerful technique to study ultrafast electronic dynamics in solids. Here, an innovative optical setup based on a 100-kHz Yb laser source is presented. Exploiting non-collinear optical parametric amplification and sum-frequency generation, ultrashort pump (hν = 1.82 eV) and ultraviolet probe (hν = 6.05 eV) pulses are generated. Overall temporal and instrumental energy resolutions of, respectively, 85 fs and 50 meV are obtained. Time- and angle-resolved measurements on BiTeI semiconductor are presented to show the capabilities of the setup.

Complete analog control of the carrier-envelope-phase of a high-power laser amplifier.

In this work we demonstrate the development of a complete analog feedback loop for the control of the carrier-envelope phase (CEP) of a high-average power (20 W) laser operating at 10 kHz repetition rate. The proposed method combines a detection scheme working on a single-shot basis at the full-repetition-rate of the laser system with a fast actuator based either on an acousto-optic or on an electro-optic crystal. The feedback loop is used to correct the CEP fluctuations introduced by the amplification process demonstrating a CEP residual noise of 320 mrad measured on a single-shot basis. The comparison with a feedback loop operating at a lower sampling rate indicates an improvement up to 45% in the residual noise. The measurement of the CEP drift for different integration times clearly evidences the importance of the single-shot characterization of the residual CEP drift. The demonstrated scheme could be efficiently applied for systems approaching the 100 kHz repetition rate regime.

Fetal cystic hygroma: the importance of natural history.

OBJECTIVES: To evaluate the natural history of cystic hygroma (CH) in fetal and neonatal periods to enrich parental counselling. Ultrasonographic characteristics, associated syndromes, chromosomal anomalies, fetal cardiac pathology and life after birth were considered. STUDY DESIGN: From May 1985 to September 2010, 207 pregnancies were seen the authors' centre with suspected vascular-lymphatic fetal malformation: 156 of them had CH. Cases were followed up by telephone interview to determine fetal and neonatal outcomes. Chi-squared test was used for statistical analysis. RESULTS: Among the 156 cases of CH, the condition was septated in 75% of cases, associated with other pathologies in 74%, and retronuchal in 88%. Intrauterine regression was seen in 36% of cases, with complete disappearance in 77%. The karyotype was normal in 55% of cases. Follow-up was completed in 85 cases and revealed 54 spontaneous abortions (63%) and 31 live births (37%). Amongst these, 21 out of 31 children had a favourable outcome (68%). A negative embryo-fetal outcome was significantly associated with CH being associated with other pathologies, such as hydrops, retronuchal position and altered karyotype. Spontaneous regression or resolution of CH was associated with live births. CONCLUSIONS: The management of pregnancies with a diagnosis of fetal CH requires knowledge of natural history of the malformation for appropriate parental counselling.

Ultrafast collinear scattering and carrier multiplication in graphene.

Graphene is emerging as a viable alternative to conventional optoelectronic, plasmonic and nanophotonic materials. The interaction of light with charge carriers creates an out-of-equilibrium distribution, which relaxes on an ultrafast timescale to a hot Fermi-Dirac distribution, that subsequently cools emitting phonons. Although the slower relaxation mechanisms have been extensively investigated, the initial stages still pose a challenge. Experimentally, they defy the resolution of most pump-probe setups, due to the extremely fast sub-100 fs carrier dynamics. Theoretically, massless Dirac fermions represent a novel many-body problem, fundamentally different from Schrödinger fermions. Here we combine pump-probe spectroscopy with a microscopic theory to investigate electron-electron interactions during the early stages of relaxation. We identify the mechanisms controlling the ultrafast dynamics, in particular the role of collinear scattering. This gives rise to Auger processes, including charge multiplication, which is key in photovoltage generation and photodetectors.

Ultrafast spectroscopy of linear carbon chains: the case of dinaphthylpolyynes.

The dynamics of excited states in α,ω-dinaphthylpolyyne, a class of linear sp-carbon chains, has been investigated by ultrafast transient absorption spectroscopy and DFT//TDDFT calculations. We show that the role of molecular conformers, in which end-capped naphthalene rings are planar or perpendicular to the polyyne plane, is fundamental for understanding both the steady state properties, such as UV-Vis absorption spectra and vibronic transitions, and the ultrafast transient absorption features. In particular, we observed in one of the conformers the ultrafast formation of a narrow photo-induced absorption band rising within 30 ps. This band can be assigned to an inter-system crossing event leading to the formation of triplet excited states.

Coherent synthesis of ultra-broadband optical parametric amplifiers.

We report on coherent synthesis of two ultra-broadband optical parametric amplifiers, each compressed by chirped mirror pairs, resulting in almost-octave-spanning (520-1000 nm) spectra supporting nearly single-cycle sub-4 fs pulse duration. Synthesized pulse timing is locked to less than 30 as by a balanced optical cross-correlator. The synthesized pulse is characterized by two-dimensional spectral interferometry and has a 3.8 fs duration.

[Sacrococcygeal teratoma: single center experience and functional long-term follow-up]. / Teratoma sacrococcigeo: esperienza monocentrica e follow-up funzionale a lungo termine.

OBJECTIVE: To propose long-term follow-up protocol to analyse clinical and functional aspects and evaluate the Quality of Life (QoL) of patients with Sacrococcygeal Teratoma (SCT). MATERIALS AND METHODS: The long-term follow-up of 14 out of 28 patients has been assessed through the retrospective review of data related to antenatal diagnosis, obstetric pathology and surgery, collected from July 1985 to December 2009. It has been accomplished by analysing functional and aesthetic outcomes and the QoL experienced by the patients with an average observation range of 121 months for each patient. RESULTS: Concerning the anorectal functionality, 14% of patients reported impairment of fecal continence while 36% had completely normal bowel habits. Other health problems varying from urinary incontinence to neurogenic bladder were reported by 36% of patients. Dealing with the functionality of lower limbs, 20% of patients exhibited minor dysfunctions while 7% major ones. Optimal aesthetic outcome of the surgical scar has been reported only by 21% of the specimen. The evaluation of QoL pointed out that 64% of patients are moderately satisfied while 36% presented problems. CONCLUSIONS: We believe that functional sequelae should play an important role during antenatal counselling and that the urological and anorectal follow-up for SCT patients should be long-term evaluated. Furthermore, aesthetic aspects and psychological support should be taken into account carefully especially during childhood.