A candidate supermassive binary black hole system in the brightest cluster galaxy of RBS 797

The radio source at the center of the cool core galaxy cluster RBS 797 (z=0.35) is known to exhibit a misalignment of its radio jets and lobes observed at different VLA-scale, with the innermost kpc-scale jets being almost orthogonal to the radio emission which extends for tens of kpc filling the X-ray cavities. Gitti et al. suggested that this peculiar radio morphology may indicate a recurrent activity of the central radio source, where the jet orientation is changing between the different outbursts due to the effects of supermassive binary black holes (SMBBHs). We aim at unveiling the nuclear radio properties of the brightest cluster galaxy (BCG) in RBS 797 and at investigating the presence of a SMBBH system in its center. We have performed new high-resolution observations at 5 GHz with the European VLBI Network (EVN), reaching an angular resolution of 9x5 mas^2 and a sensitivity of 36 microJy/beam. We report the EVN detection of two compact components in the BCG of RBS 797, with a projected separation of ~77 pc. We can envisage two possible scenarios: the two components are two different nuclei in a close binary system, or they are the core and a knot of its jet. Both interpretations are consistent with the presence of SMBBHs. Our re-analysis of VLA archival data seems to favor the first scenario, as we detect two pairs of radio jets misaligned by ~90 degrees on the same kpc scale emanating from the central radio core. If the two outbursts are almost contemporaneous, this is clear evidence of the presence of two active SMBHs, whose radio nuclei are unresolved at VLA resolution. The nature of the double source detected by our EVN observations in the BCG of RBS 797 can be established only by future sensitive, multi-frequency VLBI observations. If confirmed, RBS 797 would be the first SMBBH system observed at medium-high redshift at VLBI resolution. (abridged)Comment: 4 pages, 2 figures, A&A Letter in pres

The mystery of the 'Kite' radio source in Abell 2626: insights from new Chandra observations

We present the results of a new Chandra study of the galaxy cluster A2626. The radio emission of the cluster shows a complex system of four symmetric arcs without known correlations with the X-ray emission. The mirror symmetry of the radio arcs toward the center and the presence of two optical cores in the central galaxy suggested that they may be created by pairs of precessing radio jets powered by dual AGNs inside the cD galaxy. However, previous observations failed to observe the second jetted AGN and the spectral trend due to radiative age along the radio arcs, thus challenging this interpretation. The new Chandra observation had several scientific objectives, including the search for the second AGN that would support the jet precession model. We focus here on the detailed study of the local properties of the thermal and non-thermal emission in the proximity of the radio arcs, in order to get more insights into their origin. We performed a standard data reduction of the Chandra dataset deriving the radial profiles of temperature, density, pressure and cooling time of the intra-cluster medium. We further analyzed the 2D distribution of the gas temperature, discovering that the south-western junction of the radio arcs surrounds the cool core of the cluster. We studied the X-ray SB and spectral profiles across the junction, finding a cold front spatially coincident with the radio arcs. This may suggest a connection between the sloshing of the thermal gas and the nature of the radio filaments, raising new scenarios for their origin. A possibility is that the radio arcs trace the projection of a complex surface connecting the sites where electrons are most efficiently reaccelerated by the turbulence that is generated by the gas sloshing. In this case, diffuse emission embedded by the arcs and with extremely steep spectrum should be most visible at very low radio frequencies.Comment: 7 pages, 7 figures. Accepted for publication on A&

A morphological comparison between giant radio halos and radio mini--halos in galaxy clusters

In this letter we present a morphological comparison between giant radio halos and radio mini-halos in galaxy clusters based on radio--X-ray luminosity, P_{1.4}-L_X, and radio luminosity-size, P_{1.4}-R_H, correlations. We report evidence that P_{1.4}-L_X and P_{1.4}-R_H trends may also exist for mini--halos: mini--halo clusters share the same region of giant halo clusters in the (P_{1.4},L_X) plane, whereas they are clearly separated in the (P_{1.4},R_H) plane. The synchrotron emissivity of mini-halos is found to be more than 50 times larger than that of giant halos, implying a very efficient process for their origins. By assuming a scenario of sporadical turbulent particle re-acceleration for both giant and mini halos, we discuss basic physical differences between these sources. Regardless of the origin of the turbulence, a more efficient source of injection of particles, which eventually takes part in the re-acceleration process, is required in mini-halos, and this may result from the central radio galaxy or from proton-proton collisions in the dense cool core regions.Comment: 4 pages, 3 figures, A&A Letter in pres

ALMA observations of molecular clouds in three group centered elliptical galaxies: NGC 5846, NGC 4636, and NGC 5044

We present new ALMA CO(2--1) observations of two well studied group-centered elliptical galaxies: NGC~4636 and NGC~5846. In addition, we include a revised analysis of Cycle 0 ALMA observations of the central galaxy in the NGC~5044 group that has been previously published. We find evidence that molecular gas, in the form of off-center orbiting clouds, is a common presence in bright group-centered galaxies (BGG). CO line widths are $\gtrsim 10$ times broader than Galactic molecular clouds, and using the reference Milky Way $X_{CO}$, the total molecular mass ranges from as low as $2.6\times 10^5 M_\odot$ in NGC~4636 to $6.1\times 10^7 M_\odot$ in NGC~5044. With these parameters the virial parameters of the molecular structures is $\gg 1$. Complementary observations of NGC~5846 and NGC~4636 using the ALMA Compact Array (ACA) do not exhibit any detection of a CO diffuse component at the sensitivity level achieved by current exposures. The origin of the detected molecular features is still uncertain, but these ALMA observations suggest that they are the end product of the hot gas cooling process and not the result of merger events. Some of the molecular clouds are associated with dust features as revealed by HST dust extinction maps suggesting that these clouds formed from dust-enhanced cooling. The global nonlinear condensation may be triggered via the chaotic turbulent field or buoyant uplift. The large virial parameter of the molecular structures and correlation with the warm ($10^3 - 10^5 K$)/hot ($\ge10^6$) phase velocity dispersion provide evidence that they are unbound giant molecular associations drifting in the turbulent field, consistently with numerical predictions of the chaotic cold accretion process. Alternatively, the observed large CO line widths may be generated by molecular gas flowing out from cloud surfaces due to heating by the local hot gas atmosphere.Comment: Revised version to be published in ApJ, 16 pages, 10 figures, 4 table

Risk Factors for Multiple Malignancies in the Head and Neck

Original research articl

Effectiveness and pitfalls of elective neck dissection in N0 laryngeal cancer

The aim of the study was to evaluate the efficacy and potential pitfalls of selective neck dissection of levels II-IV in controlling occult neck disease in clinically negative neck (cN0) of patients with laryngeal squamous cell carcinoma. Charts of 96 consecutive cN0 laryngeal cancer patients undergoing 122 neck dissections at the University of Florence from January 2000 to December 2004 were reviewed. N0 neck was defined with contrast enhanced computed tomography scan. Occult neck disease rate was 12.5%, involvement per level was: 47.6% at level II, 38.1% at level III, 9.5% at level IV. Six patients developed neck recurrence (6.25%) after selective neck dissection of levels II-IV within the first two years after treatment. In conclusion, selective neck dissection of levels II-IV is effective in N0 laryngeal squamous cell carcinoma; posterior limits of surgical resection are missing therefore if post-operative radiation is required, the field should be extended beyond the dissected levels. The low incidence of occult neck disease indicates the need to refine treatment strategy, restricting elective neck dissection only to supraglottic T2 with epilaryngeal involvement, supraglottic T3-4 and glottic T4 tumours, and considering a "wait and see" protocol implemented with imaging techniques and cytological assessments for other lesions

A radio minihalo in the extreme cool-core galaxy cluster RXCJ1504.1-0248

Aims. We report the discovery of a radio minihalo in RXCJ1504.1-0248, a massive galaxy cluster that has an extremely luminous cool core. To date, only 9 radio minihalos are known, thus the discovery of a new one, in one of the most luminous cool-core clusters, provides important information on this peculiar class of sources and sheds light on their origin. Methods. The diffuse radio source is detected using GMRT at 327 MHz and confirmed by pointed VLA data at 1.46 GHz. The minihalo has a radius of $\sim$140 kpc. A Chandra gas temperature map shows that the minihalo emission fills the cluster cool core and has some morphological similarities to it, as has been previously observed for other minihalos. Results. The Chandra data reveal two subtle cold fronts in the cool core, likely created by sloshing of the core gas, as observed in most cool-core clusters. Following previous work, we speculate that the origin of the minihalo is related to sloshing. Sloshing may result in particle acceleration by generating turbulence and/or amplifying the magnetic field in the cool core, leading to the formation of a minihalo.Comment: 4 pages, 1 table, 3 color figures. Accepted for publication in A&A Letter

Cost analysis in oral cavity and oropharyngeal reconstructions with microvascular and pedicled flaps.

Reconstructive surgery of the head and neck region has undergone tremendous advancement over the past three decades, and the success rate of free tissue transfers has risen to greater than 95\%. It must always be considered that not all patients are ideal candidates for free flap reconstruction, and also that not every defect strictly requires a free flap transfer to achieve good functional results. At our institution, free flap reconstruction is first choice, although we use pedicled alternative flaps for most weak patients suffering from severe comorbidities, and for pretreated patients presenting a second primary or a recurrent cancer. From July 2006 to May 2010, 54 consecutive patients underwent soft tissue reconstruction of oral cavity and oropharyngeal defects. We divided the cohort in three groups: Group 1 (G1): 16 patients in good general conditions that received free radial forearm flap reconstruction; Group 2 (G2): 18 high-risk patients that received a reconstruction with infrahyoid flap; Group 3 (G3): 20 patients that received temporal flap (10 cases) or pectoral flap (10 cases) reconstruction. We must highlight that pedicled alternative flaps were used in elderly, unfavourable and weak patients, where usually the medical costs tend to rise rather than decrease. We compared the healthcare costs of the three groups, calculating real costs in each group from review of medical records and operating room registers, and calculating the corresponding DRG system reimbursement. For real costs, we found a statistically significant difference among groups: in G1 the average total cost per patient was € 22,924, in G2 it was € 18,037 and in G3 was € 19,872 (p = 0.043). The amount of the refund, based on the DRG system, was € 7,650 per patient, independently of the type of surgery. Our analysis shows that the use of alternative non-microvascular techniques, in high-risk patients, is functionally and oncologically sound, and can even produce a cost savings. In particular, the infrahyoid flap (G2) ensures excellent functional results, accompanied by the best economic savings in the worst group of patients. Our data reflect a large disconnection between the DRG system and actual treatment costs.Abstract available from the publisher

Palliative combined treatment for unresectable cutaneous basosquamous cell carcinoma of the head and neck.

A case is presented of a patient with a skin basosquamous cell carcinoma of the frontal region infiltrating the cerebral tissue and with a widespread unresectable regional metastatic ulceration of the left parotid region. The patient underwent combined palliative treatment: surgical coverage of the ulceration by means of a pectoralis mayor flap transposition and radiotherapy. After 18 months of follow-up, no signs of tumour progression were noted, the patient is currently free from pain, no increase in trismus was seen, and a slight gain in weight was recorded. Unresectable cancer is mainly treated by concurrent chemoradiation; radiotherapy, however, is contraindicated in deep neoplastic ulcerations with exposure of large vessels. The data reported suggest that surgical coverage of an unresectable neoplastic ulcer is feasible, and combined with early administration of radiation permits a palliative approach in an otherwise untreatable condition.Abstract available from the publisher