2,209 research outputs found
Particle Pair Production in Cosmological General Relativity
The Cosmological General Relativity (CGR) of Carmeli, a 5-dimensional (5-D)
theory of time, space and velocity, predicts the existence of an acceleration
a_0 = c / tau due to the expansion of the universe, where c is the speed of
light in vacuum, tau = 1 / h is the Hubble-Carmeli time constant, where h is
the Hubble constant at zero distance and no gravity.
The Carmeli force on a particle of mass m is F_c = m a_0, a fifth force in
nature.
In CGR, the effective mass density rho_eff = rho - rho_c, where rho is the
matter density and rho_c is the critical mass density which we identify with
the vacuum mass density rho_vac = -rho_c.
The fields resulting from the weak field solution of the Einstein field
equations in 5-D CGR and the Carmeli force are used to hypothesize the
production of a pair of particles.
The mass of each particle is found to be m = tau c^3 / 4 G, where G is
Newton's constant.
The vacuum mass density derived from the physics is rho_vac = -rho_c = -3 /
(8 pi G tau^2).
The cosmic microwave background (CMB) black body radiation at the temperature
T_o = 2.72548 K which fills that volume is found to have a relationship to the
ionization energy of the Hydrogen atom. Define the radiation energy
epsilon_gamma = (1 - g) m c^2 / N_gamma, where (1-g) is the fraction of the
initial energy m c^2 which converts to photons, g is a function of the baryon
density parameter Omega_b and N_gamma is the total number of photons in the CMB
radiation field. We make the connection with the ionization energy of the first
quantum level of the Hydrogen atom by the hypothesis epsilon_gamma = [(1 - g) m
c^2] / N_gamma = alpha^2 mu c^2 / 2, where alpha is the fine-structure constant
and mu = m_p f / (1 + f), where f= m_e / m_p with m_e the electron mass and m_p
the proton mass.Comment: 14 pages, 0 figures. The final publication is available at
springerlink.co
Clinical, epidemiological, and microbiological characteristics of bacteremia caused by high-level gentamicin-resistant Enterococcus faecalis
Enterococcus spp bacteremia is associated with high mortality and the appearance of high-level gentamicin resistance (HLGR) created additional challenges for the treatment of these infections. We evaluated the epidemiological and clinical characteristics of patients with bacteremias caused by HLGR and non_HLGR Enterococcus faecalis isolates at a teaching hospital in the State of São Paulo, Brazil. Patients with bacteremia due to E. faecalis diagnosed between January 1999 and December 2003 were included in the study. We collected clinical, epidemiological, and microbiological data from medical records. Banked isolates were typed using pulsed-field gel electrophoresis. We identified 145 cases of E. faecalis bacteremia: 66 (45.5%) were caused by HLGR isolates and 79 (54.5%) by non_HLGR. In the univariate analysis, patients with HLGR infection were older, had higher rates of bladder catheterization, and more often had treatment with cephalosporin, quinolone, and/or carbapenem compared with patients with non_HLGR infection (P < 0.05). Multivariate analysis indicated that older age, hematological malignancy, and previous use of vancomycin were independently associated with HLGR (P < 0.05). Mortality rates were not significantly different among patients with HLGR (50%) and non_HLGR (43%) infections (P = 0.40). Of the 32 genotyped isolates, 16 were distributed into 6 main electrophoresis patterns and 16 others had distinct patterns. E. faecalis bacteremia is associated with high mortality and is frequently caused by HLGR isolates at this teaching hospital. The variability among genotyped isolates suggests that endogenous infections, rather than patient-to-patient transmission of E. faecalis, are more common at this institution.89089
Finite bounded expanding white hole universe without dark matter
The solution of Einstein's field equations in Cosmological General Relativity
(CGR), where the Galaxy is at the center of a finite yet bounded spherically
symmetrical isotropic gravitational field, is identical with the unbounded
solution. This leads to the conclusion that the Universe may be viewed as a
finite expanding white hole. The fact that CGR has been successful in
describing the distance modulus verses redshift data of the high-redshift type
Ia supernovae means that the data cannot distinguish between unbounded models
and those with finite bounded radii of at least . Also it is shown that
the Universe is spatially flat at the current epoch and has been at all past
epochs where it was matter dominated.Comment: 11 pages, revised versio
Laparoscopic Upper-pole Nephroureterectomy In Infants
Objective: Report the results of laparoscopic upper-pole nephroureterectomy in infants. Materials and Methods: Six consecutive infants underwent 7 laparoscopic upper-pole nephroureterectomy. Pre and post-operative evaluation included renal sonography, voiding cystourethrogram and renal scintigraphy. All infants showed upper-pole exclusion. Surgery was performed through a transperitoneal approach with full flank position in all infants. Three or 4 ports were used according to the necessity of retracting the liver. The distal ureter was ligated close to the bladder whenever reflux was present and the dysplastic upper-pole was divided with the help of an electrocautery. Data regarding operative time, postoperative use of analgesics, time to resume oral feeding, hospital stay and tubular function were collected and analyzed. Results: All procedures were concluded as planned. Mean operative time was 135 min. One patient underwent staged bilateral upper-pole nephrectomy. There were no complications and the postoperative hospital stay was 48 hours in 5 procedures and 24 hours in 2 procedures. Pain medication was required only in the first day. Renal tubular function showed improvement in half of the cases. Conclusion: Laparoscopic partial nephrectomy is a safe and feasible procedure in infants. Due to the magnification provided by the lenses, a better vision of the structures is achieved, facilitating selective dissection of vascular upper-pole, renal parenchyma and distal ureter. This approach is less damaging to the lower pole, and is associated to low morbidity and a short hospital stay.3318791Peters, C.A., Laparoscopic and robotic approach to genitourinary anomalies in children (2004) Urol Clin North Am, 31, pp. 595-605Robinson, B.C., Snow, B.W., Cartwright, P.C., De Vries, C.R., Hamilton, B.D., Anderson, J.B., Comparison of laparoscopic versus open partial nephrectomy in a pediatric series (2003) J Urol, 169, pp. 638-640Steyaert, H., Valla, J.S., Minimally invasive urologic surgery in children: An overview of what can be done (2005) Eur J Pediatr Surg, 15, pp. 307-313Koyle, M.A., Woo, H.H., Kavoussi, L.R., Laparoscopic nephrectomy in the first year of life (1993) J Pediatr Surg, 28, pp. 693-695Valla, J.S., Breaud, J., Carfagna, L., Tursini, S., Steyaert, H., Treatment of ureterocele on duplex ureter: Upper pole nephrectomy by retroperitoneoscopy in children based on a series of 24 cases (2003) Eur Urol, 43, pp. 426-429Jordan, G.H., Winslow, B.H., Laparoendoscopic upper pole partial nephrectomy with ureterectomy (1993) J Urol, 150, pp. 940-943Horowitz, M., Shah, S.M., Ferzli, G., Syad, P.I., Glassberg, K.I., Laparoscopic partial upper pole nephrectomy in infants and children (2001) BJU Int, 87, pp. 514-516Gill, I.S., Delworth, M.G., Munch, L.C., Laparoscopic retroperitoneal partial nephrectomy (1994) J Urol, 152, pp. 1539-1542Borzi, P.A., A comparison of the lateral and posterior retroperitoneoscopic approach for complete and partial nephroureterectomy in children (2001) BJU Int, 87, pp. 517-520Desgrandchamps, F., Gossot, D., Jabbour, M.E., Meria, P., Teillac, P., Le Duc, A., A 3 trocar technique for transperitoneal laparoscopic nephrectomy (1999) J Urol, 161, pp. 1530-1532Hulbert, W.C., Rabinowitz, R., Prenatal diagnosis of duplex system hydronephrosis: Effect on renal salvage (1998) Urology, 51, pp. 23-26El-Ghoneimi, A., Farhat, W., Bolduc, S., Bagli, D., McLorie, G., Khoury, A., Retroperitoneal laparoscopic vs open partial nephroureterectomy in children (2003) BJU Int, 91, pp. 532-535Jednak, R., Kryger, J.V., Barthold, J.S., Gonzalez, R., A simplified technique of upper pole heminephrectomy for duplex kidney (2000) J Urol, 164, pp. 1326-1328Borzi, P.A., Yeung, C.K., Selective approach for transperitoneal and extraperitoneal endoscopic nephrectomy in children (2004) J Urol, 171, pp. 814-816Guillonneau, B., Ballanger, P., Lugagne, P.M., Valla, J.S., Vallancien, G., Laparoscopic versus lumboscopic nephrectomy (1996) Eur Urol, 29, pp. 288-291Janetschek, G., Seibold, J., Radmayr, C., Bartsch, G., Laparoscopic heminephroureterectomy in pediatric patients (1997) J Urol, 158, pp. 1928-193
Variation in quality of newly hatched chicks from Japanese breeder quail fed guava extract
The aim of this study was to evaluate the effects of guava extract as a dietary supplement for Japanese quail hens on incubation parameters, intestinal development, and the quality of newly hatched chicks. Six hundred and forty-eight eggs were collected from Japanese quail hens fed diets with 0.0, 3.0, 6.0, and 9.0 g/kg of guava extract. The study consisted of four treatments, six replicates, and 27 eggs per replicate. The guava extract contained 2% ellagic acid. The eggs were incubated at 37.5 °C and 65% relative air humidity. The hatch window, hatchability, embryo development in unhatched eggs, quality of newly hatched quails, and intestinal histomorphometry of a duodenum segment were evaluated. Differences among the treatments in hatchability and the hatch window were not significant. The guava extract did not affect mortality rate, live pecking, dead pecking, and contaminated and inverted eggs. The number of infertile eggs was lower in the groups that received 3.0 and 9.0 g/kg of extract in their diets. Use of up to 3.0 g/kg of guava extract in the diet increased the weight of both eggs and newly hatched chicks. The quality score of newly hatched quail was similar across treatments. The inclusion of 3.0 g/kg of guava extract in the diet of Japanese quail breeder hens increased the hatchling weight of the chicks and improved the villus to crypt ratio of their duodenum.
Keywords: embryology, embryo metabolism, hatchery, incubation, breeder nutritio
A small universe after all?
The cosmic microwave background radiation allows us to measure both the
geometry and topology of the universe. It has been argued that the COBE-DMR
data already rule out models that are multiply connected on scales smaller than
the particle horizon. Here we show the opposite is true: compact (small)
hyperbolic universes are favoured over their infinite counterparts. For a
density parameter of Omega_o=0.3, the compact models are a better fit to
COBE-DMR (relative likelihood ~20) and the large-scale structure data (sigma_8
increases by ~25%).Comment: 4 pages, RevTeX, 7 Figure
Controlling quantum entanglement through photocounts
We present a protocol to generate and control quantum entanglement between
the states of two subsystems (the system ) by making measurements on
a third subsystem (the monitor ), interacting with . For
the sake of comparison we consider first an ideal, or instantaneous projective
measurement, as postulated by von Neumann. Then we compare it with the more
realistic or generalized measurement procedure based on photocounting on . Further we consider that the interaction term (between and
) contains a quantum nondemolition variable of and discuss
the possibility and limitations for reconstructing the initial state of from information acquired by photocounting on .Comment: 12 pages, 3 figures, accepted for publication in Phys. Rev
Rank two quadratic pairs and surface group representations
Let be a compact Riemann surface. A quadratic pair on consists of a
holomorphic vector bundle with a quadratic form which takes values in fixed
line bundle. We show that the moduli spaces of quadratic pairs of rank 2 are
connected under some constraints on their topological invariants. As an
application of our results we determine the connected components of the
-character variety of .Comment: 37 pages, 1 figur
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