Entangling oscillators through environment noise

We consider two independent bosonic oscillators immersed in a common bath, evolving in time with a completely positive, markovian, quasi-free (Gaussian) reduced dynamics. We show that an initially separated Gaussian state can become entangled as a result of a purely noisy mechanism. In certain cases, the dissipative dynamics allows the persistence of these bath induced quantum correlations even in the asymptotic equilibrium state.Comment: 14 pages, plain-Te

Non-equilibrium states of a photon cavity pumped by an atomic beam

We consider a beam of two-level randomly excited atoms that pass one-by-one through a one-mode cavity. We show that in the case of an ideal cavity, i.e. no leaking of photons from the cavity, the pumping by the beam leads to an unlimited increase in the photon number in the cavity. We derive an expression for the mean photon number for all times. Taking into account leaking of the cavity, we prove that the mean photon number in the cavity stabilizes in time. The limiting state of the cavity in this case exists and it is independent of the initial state. We calculate the characteristic functional of this non-quasi-free non-equilibrium state. We also calculate the energy flux in both the ideal and open cavity and the entropy production for the ideal cavity.Comment: Corrected energy production calculations and made some changes to ease the readin

Covariant Quantum Dynamical Semigroups: Unbounded generators

A survey of the probabilistic approaches to quantum dynamical semigroups with unbounded generators is given. An emphasis is made upon recent advances in the structural theory of covariant Markovian master equations. The relations with the classical Levy-Khinchin formula are elucidated. As an example, a complete characterizations of the Galilean covariant irreversible quantum Markovian evolutions is given in terms of the corresponding quantum master and Langevin equations. Important topics for future investigation are outlined.Comment: 14 pages,Latex, no figures, submitted to the Semigroup Volume, Group 21, Goslar 199

Intérêt comparé de la manométrie ano-rectale et de l'électrocardiographie dans le diagnostic de la neuropathie autonome diabétique.

Searching for silent anorectal autonomic neuropathy, we investigated the anorectal sensorimotor function in 79 continent diabetics. Thirty four per cent of the patients had a basal anal sphincter pressure lower than 40 mm Hg N = 54.5 +/- 15.5 mm Hg and 11 p. 100 had a threshold of conscious rectal sensation higher than 20 ml (N less than or equal to 20 ml). An electrocardiogram was performed and the change in heart rate resulting from successive deep breaths was recorded for each patient. Cardiac autonomic neuropathy was diagnosed when cardiac frequency did not change with ventilation. This was reflected by a ratio E/I (largest RR space during expiration on the electrocardiogram to the shortest during inspiration) close to one. Compared to cardiac criteria for autonomic neuropathy, the sensitivity of anorectal manometry in the detection of diabetic autonomic neuropathy was 77.2 p. 100 and specificity was 82 p. 100. Low basal anal sphincter pressure in asymptomatic diabetics seems to be a sensitive and specific criteria for the assessment of diabetic autonomic neuropathy and correlates closely with cardiac criteria

Acute localized diverticulitis: optimum management requires accurate staging.

Between 1977 and 1989, 151 patients were treated in our institution for acute sigmoid diverticulitis. Thirty-one patients were operated on for diffuse peritonitis, and were excluded from the study. One hundred twenty patients had localized disease. There were 59 men and 61 women, with a mean age of 60 years (range, 30 to 87 years). Thirteen were under 40 years of age. A "phlegmonous" diverticulitis (no pericolic abscess) was diagnosed in 78 cases (group I). A pericolic abscess was identified in 42 cases (group II). The medical treatment was successful in 97% of the patients of the group I. Only 15 patients required a delayed elective resection for recurrence or chronic complications, within the next 24 months. There were no operative deaths. All the other patients were doing well after a mean follow-up of 5 years (9-144 months), without any disease-related death. Patients presenting with a localized pericolic abscess (group II, n = 42) were initially treated either conservatively (n = 22) or by a more or less extensive drainage (n = 20). There were two deaths in the "conservative" group. Primary or delayed colonic resection was indicated in 34 cases because of uncontrolled sepsis, recurrence or secondary chronic complications. It is concluded that accurate classification of the disease is essential. If no peritonitis has developed, the presence of an abscess is the main determinant in both prognosis and treatment. Most patients who develop an acute phlegmonous diverticulitis do well with conservative treatment, and prophylactic resection is not indicated. Curative colectomy is reserved for patients developing persistent complications over the next few months.(ABSTRACT TRUNCATED AT 250 WORDS