b \bar b b\bar b production in proton-nucleus collisions at the LHC

A sizable rate of events, with several pairs of $b$-quarks produced contemporarily by multiple parton interactions, may be expected at very high energies as a consequence of the large parton luminosities. The production rates are further enhanced in hadron-nucleus reactions, which may represent a convenient tool to study the phenomenon. We compare the different contributions to $b{\bar b}b{\bar b}$ production, due to single and double parton scatterings, in collisions of protons with nuclei at the CERN-LHC.Comment: 13 pages, 4 figure

Double parton distributions in the leading logarithm approximation of perturbative QCD

Recent CDF measurements of the inclusive cross section for a double parton scattering attach a great importance to any theoretical calculations of two-particle distribution functions. Using a parton interpretation of the leading logarithm diagrams of perturbative QCD theory, generalized Lipatov-Altarelli-Parisi-Dokshitzer equations for the two-parton distributions are re-obtained. The solutions of these equations are not at all the product of two single-parton distributions what is usually applied to the current analysis as ansatz.Comment: 8 pages, LaTe

Scale Factor in Double Parton Collisions and Parton Densities in Transverse Space

The scale factor $\sigma_{eff}$, which characterizes double parton collisions in high energy hadron interactions, is a direct manifestation of the distribution of the interacting partons in transverse space, in such a way that different distributions give rise to different values of $\sigma_{eff}$ in different double parton collision processes. We work out the value of the scale factor in a few reactions of interest, in a correlated model of the multi-parton density of the proton recently proposed.Comment: 10 pages, 2 figure

Rare spontaneous monochorionic dizygotic twins: a case report and a systematic review

Background: Monochorionic dizygotic twins are a rare condition, mostly related to assisted reproductive technology. This type of twinning is burdened by the same risk of pregnancy complications found in monochorionic monozygotic pregnancies. Case presentation: We report a case of spontaneous monochorionic dizygotic twins sharing situs inversus abdominalis and isolated levocardia, with only one twin affected by biliary atresia with splenic malformation syndrome. We also conducted a literature review of the 14 available documented monochorionic dizygotic twin gestations spontaneously conceived. Conclusions: It is still unclear how this unusual type of twinning can occur in spontaneous conception. The evidence so far suggest the importance to timely diagnose the chorionicity, in order to adequately manage the typical complications associated with monochorionicity

Total Face Approach (TFA): a novel 3D approach to describe the main cephalometric craniomaxillofacial parameters

The aim of this study is to propose a 3D skeletal classification and relative normal values of reference. Method: from a pool of 271 cone-beam computerized tomography images 108 chinsummit examinations of the skull were selected and divided into 3 traditional skeletal classes. The same Cone-beam Computerized Tomography (CBCT) images were then assessed using the cephalometric multiplanar analysis following the total face approach protocol. Results: the results of this study indicate standard 3D cephalometric norms for the vertical and sagittal evaluation of the skull. Conclusions: data obtained from our measurements allowed the creation of intervals supplying nosological classification that could be used in orthodontics, orthognatic surgery and implant surgery in fully edentulous patients

Possible explanations for different surface quality in laser cutting with 1 micron and 10 microns beams

In laser　cutting　of　thick　steel　sheets,　quality　difference　is　observed　between　cut　surfaces　obtained　with 1 micron and 10 micron laser beams. This paper investigates physical mechanisms for this interesting and important problem of the wavelength dependence. First, striation generation process is described, based on a 3D structure of melt flow on a kerf front, which was revealed for the first time by our recent experimental observations. Two fundamental processes are suggested to explain the difference in the cut surface quality: destabilization of the melt flow in the central part of the kerf front and downward displacement of discrete melt accumulations along the side parts of the front. Then each of the processes is analyzed using a simplified analytical model. The results show that in both processes, different angular dependence of the absorptivity of the laser beam can result in the quality difference. Finally we propose use of radial polarization to improve the quality with the 1 micron wavelength

Case Report: Anterior Cruciate Ligament Calcification in a Patient With Chondrocalcinosis: Micro-Computed Tomography Presentation

In this case report, an incidental postoperative diagnosis of anterior cruciate ligament (ACL) calcification, associated with calcification of posterior cruciate ligament (PCL) and lateral meniscus insertions, was made using micro-computed tomography (μCT) technology in a knee specimen obtained during a total knee replacement (TKR) surgery due to painful tri-compartmental osteoarthritis (OA) with chondrocalcinosis signs at preoperative X-ray. Anterior cruciate ligament calcification is an uncommon finding, and conventional X-ray and MRI are not so helpful in its identification. μCT scan, in contrast, is of interest because it provides highly spatial three-dimensional information with excellent visualization of bones and calcifications. The μCT technology used in this case report allowed us to perform a detailed analysis and a 3-D reconstruction of the calcium pyrophosphate dihydrate (CPPD) crystal deposition about the knee without the need to section the specimens into slice as performed in previous studies. The 3-D model obtained with μCT scan permits to gain more insight into the shape of the calcification within the fibers of the ligamentous structures of the joint

Same-sign W pair production as a probe of double parton scattering at the LHC

We study the production of same-sign W boson pairs at the LHC in double parton interactions. Compared with simple factorised double parton distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to non-trivial kinematic correlations between the W bosons. A numerical study of the prospects for observing this process using same-sign dilepton signatures, including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV centre-of-mass energy is then performed. It is shown that a small excess of same-sign dilepton events from double parton scattering over a background dominated by single scattering WZ(gamma*) production could be observed at the LHC.Comment: 14 pages, 8 figures. Added references, slight changes in the text

Severe bicompartmental bone bruise is associated with rotatory instability in anterior cruciate ligament injury

Purpose: The presence and severity of bone bruise is more and more investigated in the non-contact anterior cruciate ligament (ACL) injury context. Recent studies have advocated a correlation between bone bruise and preoperative knee laxity. The aim of the present study was to investigate the correlation between bone bruise and preoperative rotatory knee laxity. Methods: Twenty-nine patients (29.1 ± 9.8 years) with MRI images at a maximum of 3 months after ACL injury (1.6 ± 0.8 months) were included. The bone bruise severity was evaluated according to the International Cartilage Repair Society (ICRS) scale for lateral femoral condyle, lateral tibial plateau, medial femoral condyle, and medial tibial plateau. The intraoperative rotational knee laxity was evaluated through a surgical navigation system in terms of internal–external rotation at 30° and 90° of knee flexion (IE30, IE90) and internal–external rotation and acceleration during pivot-shift test (PS IE, PS ACC). The KOOS score was also collected. The association between ICRS grade of bone bruise and rotational laxity or KOOS was investigated. Results: Significant correlation (p < 0.05) was found between the bone bruise severity on the medial tibial plateau and rotational laxity (IE90, PS IE, and PS ACC) and between the severity of bone bruise on femoral lateral condyle and KOOS-Symptoms sub-score. The presence of bone bruise on the medial tibial plateau was significantly associated with a lateral femoral notch sign > 2 mm (very strong odds ratio). No kinematical differences were found between none-to-deep and extensive-generalized lateral bone bruise, while higher IE30 and IE90 were found in extensive-generalized bicompartmental bone bruise than isolated extensive-generalized lateral bone bruise. Conclusion: A severe bicompartmental bone bruise was related to higher rotatory instability in the intraoperative evaluation of ACL deficient knees. The severity of edema on the medial tibial plateau was directly correlated with higher intraoperative pivot shift, and the size of edema on the lateral femoral condyle was associated with lower preoperative clinical scores. Level of evidence: Level II