Extra dimensions, orthopositronium decay, and stellar cooling

In a class of extra dimensional models with a warped metric and a single brane the photon can be localized on the brane by gravity only. An intriguing feature of these models is the possibility of the photon escaping into the extra dimensions. The search for this effect has motivated the present round of precision orthopositronium decay experiments. We point out that in this framework a photon in plasma should be metastable. We consider the astrophysical consequences of this observation, in particular, what it implies for the plasmon decay rate in globular cluster stars and for the core-collapse supernova cooling rate. The resulting bounds on the model parameter exceed the possible reach of orthopositronium experiments by many orders of magnitude.Comment: 13 pages, no figure

Stellar Recipes for Axion Hunters

There are a number of observational hints from astrophysics which point to the existence of stellar energy losses beyond the ones accounted for by neutrino emission. These excessive energy losses may be explained by the existence of a new sub-keV mass pseudoscalar Nambu--Goldstone boson with tiny couplings to photons, electrons, and nucleons. An attractive possibility is to identify this particle with the axion -- the hypothetical pseudo Nambu--Goldstone boson predicted by the Peccei--Quinn solution to the strong CP problem. We explore this possibility in terms of a DFSZ-type axion and of a KSVZ-type axion/majoron, respectively. Both models allow a good global fit to the data, prefering an axion mass around 10 meV. We show that future axion experiments -- the fifth force experiment ARIADNE and the helioscope IAXO -- can attack the preferred mass range from the lower and higher end, respectively. An axion in this mass range can also be the main constituent of dark matter.Comment: 32 pages, 5 figure

Nucleon-Nucleon Bremsstrahlung emission of massive Axion

We consider the problem of axion production by bremsstrahlung emission in a nuclear medium. The usual assumption of a massless axion is replaced by more general hypotheses, so that we can describe the emission process for axions with mass up to a few MeV. We point out that in certain physical situations the contribution from non-zero mass is non-negligible. In particular, in the mechanism for the production of Gamma Ray Bursts via emission of heavy axions the axion mass m_a ~ 1MeV is comparable with the temperature of the nuclear medium and thus can not be disregarded. Looking at our results we find, in fact, a fairly considerable reduction of the axion luminosity in that mechanism.Comment: 16 pages, 5 figure

LIMB BODY WALL COMPLEX IN TWO HETEROZYGOTIC TWINS: A CASE REPORT

Introdution. Limb-Body Wall Complex (LBWC) is a congenital defect which includes at least two of the following characteristics: abdominal and/or thoracic body wall defects, exencephaly or encephalocoele with or without craniofacial defects (56%) and spinal defects associated with marked vertebral or sacral defects (95%). Case Report. We present a case report of an infant with LBWC, borned by diamniotic twin pregnancy. A prenatal ultrasound reported an healthy fetus and a fetus with multiple malformations. At birth we found a big abdominal wall defect, absence of scrotal sac and testicles, asymmetric chest and no major deformities in craniofacial region. At 2 hours of life, we removed the amniotic sac, we put the stomach and the spleen in the abdominal cavity, which is virtual, and positioned a spring-loaded silo. At 15th day of life we had complete reduction of the intestinal loops and liver and we closed the wall defect with a prosthesis and a cryopreserved skin. The general conditions of the patient, very severe since birth, became progressively worse and he died in the 21st day of life. Discussion. Once the diagnosis is done the physician should offer the parents a therapeutic abortion, and above all, in case they want to carry the pregnancy to term, we need to prepare them to the severity of the malformation and the high probability of death

Intracavity intensity noise suppression in the inverse Compton scattering source BriXSinO exploiting carrier-envelope offset manipulation

We report on a technique that exploits the control of the carrier -envelope offset to suppress the frequency-to-intensity noise conversion in the locking of a mode-locking laser against a high-finesse optical enhancement resonator. A proper combination of the laser carrier-envelope offset and the resonator finesse allows the improvement of the signal-to-noise ratio of the optical intensity trapped into the optical resonator. In this paper, we show the application of this technique in the laser system of the inverse Compton scattering source BriXSinO, currently under development in Milan, Italy, demonstrating the possibility of achieving an intracavity intensity noise reduction of a factor of 20

Origin and destination attachment: study of cultural integration on Twitter

The cultural integration of immigrants conditions their overall socio-economic integration as well as natives’ attitudes towards globalisation in general and immigration in particular. At the same time, excessive integration—or assimilation—can be detrimental in that it implies forfeiting one’s ties to the origin country and eventually translates into a loss of diversity (from the viewpoint of host countries) and of global connections (from the viewpoint of both host and home countries). Cultural integration can be described using two dimensions: the preservation of links to the origin country and culture, which we call origin attachment, and the creation of new links together with the adoption of cultural traits from the new residence country, which we call destination attachment. In this paper we introduce a means to quantify these two aspects based on Twitter data. We build origin and destination attachment indices and analyse their possible determinants (e.g., language proximity, distance between countries), also in relation to Hofstede’s cultural dimension scores. The results stress the importance of language: a common language between origin and destination countries favours origin attachment, as does low proficiency in the host language. Common geographical borders seem to favour both origin and destination attachment. Regarding cultural dimensions, larger differences among origin and destination countries in terms of Individualism, Masculinity and Uncertainty appear to favour destination attachment and lower origin attachment

URACHAL CYST: AN UNSPECTED COMPLICATION

The urachus is the remnant of the allantois, which usually becomes obliterated shortly after birth. Urachal remnants due to an incomplete obliteration of different portion of the urachus are rare, but they need to be treated surgically because of their potential for infectious complications and malignant degeneration. We present a case report with an unespected postoperative complication. M.E., a 10 years old boy, came to the Accident and Emergency Department for an acute abdominal pain, without other symptoms, twice in one year. The blood tests, urine sample and voiding cystourethrogram were normal. The ultrasound scan showed a thickened urachal duct. After antibiotic and anti-inflammatory therapy for two weeks, we performed laparoscopic surgery. In the second postoperative day the patient showed abdominal pain and hematuria. An ultrasound scan and a voiding cystourethrogram showed a leak from the dome of bladder. We performed an open surgery to close the defect on the bladder’s dome. The patient was discharged in 10th postoperative day. Now he is healthy. Clinically manifest persistent urachal anomalies are rare, but they carry a risk of recurrent infection and subsequent malignant degeneration. For these reasons the radical excision of the remnant is suggested. Today, due to the large laparoscopic experience, all the reports showed that this technique can be used safely, but we have to pay attention to all steps of the procedure. This case is a paradigmatic situation and it illustrates the importance of a meticulous technique during the excision of urachal remnant. Indeed even if laparoscopic excision could be safe and effective, it is not free of complication