Bounded solutions of fermions in the background of mixed vector-scalar Poeschl-Teller-like potentials

The problem of a fermion subject to a convenient mixing of vector and scalar potentials in a two-dimensional space-time is mapped into a Sturm-Liouville problem. For a specific case which gives rise to an exactly solvable effective modified Poschl-Teller potential in the Sturm-Liouville problem, bound-state solutions are found. The behaviour of the upper and lower components of the Dirac spinor is discussed in detail and some unusual results are revealed. The Dirac delta potential as a limit of the modified Poschl-Teller potential is also discussed. The problem is also shown to be mapped into that of massless fermions subject to classical topological scalar and pseudoscalar potentials. Copyright (C) EPLA, 2007.

Bounded solutions of neutral fermions with a screened Coulomb potential

The intrinsically relativistic problem of a fermion subject to a pseudoscalar screened Coulomb plus a uniform background potential in two-dimensional space-time is mapped into a Sturm-Liouville. This mapping gives rise to an effective Morse-like potential and exact bounded solutions are found. It is shown that the uniform background potential determinates the number of bound-state solutions. The behaviour of the eigenenergies as well as of the upper and lower components of the Dirac spinor corresponding to bounded solutions is discussed in detail and some unusual results are revealed. An apparent paradox concerning the uncertainty principle is solved by recurring to the concepts of effective mass and effective Compton wavelength. (c) 2005 Elsevier B.V. All rights reserved.

Exact closed-form solutions of the Dirac equation with a scalar exponential potential

The problem of a fermion subject to a general scalar potential in a two-dimensional world for nonzero eigenenergies is mapped into a Sturm-Liouville problem for the upper component of the Dirac spinor. In the specific circumstance of an exponential potential, we have an effective Morse potential which reveals itself as an essentially relativistic problem. Exact bound solutions are found in closed form for this problem. The behaviour of the upper and lower components of the Dirac spinor is discussed in detail, particularly the existence of zero modes. (c) 2005 Elsevier B.v. All rights reserved.

Best site for embryo transfer: the upper or lower half of endometrial cavity?

BACKGROUND: the objective of the present study was to determine the importance of the site of embryo transfer (upper or lower half endometrial cavity) on implantation and clinical pregnancy rates. METHODS: A total of 400 transfers guided by ultrasound were randomly assigned to two groups according to the distance between the uterine fundus and the catheter tip at the time of embryo placement. Group I (n=200) consisted of transfers corresponding to a distance of <50% of the endometrial cavity length (ECL), i.e. transfer in upper half of the cavity; and group II (n=200) consisted of transfers corresponding to a distance of greater than or equal to50%, of the ECL, i.e. transfer in lower half of cavity. The Student's t-test, Mann-Whitney test and Fisher's exact test were used where appropriate. RESULTS: the general characteristics of the study population and the main transfer cycle characteristics had an equal distribution (P>0.05) between groups I and II. No significant difference in implantation or pregnancy rates was observed between groups I and II. CONCLUSION: the implantation or pregnancy rates were similar whether the embryos were deposited in the upper or lower half of the endometrial cavity.

Effects of age and gender on upper airway, lower airway and upper lip growth

The aim of the present retrospective study was to evaluate the influence of age and gender on upper and lower airway width and upper lip length. In this study, 390 lateral cephalograms were divided into 13 age groups (ranging from 6 to 18 years) and were analyzed. The inter-group differences were analyzed using a MANOVA (Multivariate Analysis of the Variance), and the intragroup differences were analyzed using an ANOVA (Analysis of the Variance) and Tukey's test. The results of the present study indicated that although the airway width and the upper lip length increased with age, the lower airway width exhibited variable growth between the ages of six and eighteen years. The airway width was significantly greater in females than males, whereas the upper airway width was similar between these two genders. The lip length was significantly shorter in females than males. The lower airway width and upper lip length were significantly different between males and females, whereas the upper airway width was similar for the genders. The upper airway width and upper lip exhibited incremental growth between the ages of six and eighteen years. The upper lip closely followed the growth pattern of the upper airway width; the growth plateaued between the ages of 6 and 9 years, increased from 9 to 16 years and plateaued from 16 to 18 years.

Lower bounds on blow up solutions of the three-dimensional Navier-Stokes equations in homogeneous Sobolev spaces

Suppose that u(t) is a solution of the three-dimensional Navier-Stokes equations, either on the whole space or with periodic boundary conditions, that has a singularity at time T. In this paper we show that the norm of u(T - t) in the homogeneous Sobolev space (H)over dot(s) must be bounded below by c(s)t(-(2s-1)/4) for 1/2 < s < 5/2 (s not equal 3/2), where c(s) is an absolute constant depending only on s; and by c(s)parallel to u(0)parallel to((5-2s)/5)(L2)t(-2s/5) for s > 5/2. (The result for 1/2 < s < 3/2 follows from well-known lower bounds on blowup in Lp spaces.) We show in particular that the local existence time in (H)over dot(s)(R-3) depends only on the (H)over dot(s)-norm for 1/2 < s < 5/2, s not equal 3/2. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4762841]

Magnetic properties of Cu1+xMn2-xO4 and Ni1+xMn2-xO4 solid solutions

Magnetic properties of two spinel oxides solid solutions, Cul+xMn2-xO4 and Ni1+xMn2-xO4 are reported. These series are characterized by two magnetic transitions: the upper one, of ferrimagnetic type, occurs at about 85 K (for copper-based) and at 105-110 K (for nickel-based spinels), independently of the x-content: the lower transition may be related to a Neel-type collinear ordering and takes place at 30 and 45 K, respectively. Application of moderate fields (H > 250 Oe) make both transitions to merge into one broad maximum in the magnetization, which takes place at lower temperature when applying larger fields. Magnetization cycles with temperature (ZFC/FC) or field (loops) allowed us to well characterize the ordered state. The effective moment follows the expected behavior when manganese ions are being substituted by ions of lower magnetic moment (Ni(2+)andCU(2+)). (c) 2007 Elsevier Ltd. All rights reserved.

An infection control protocol: effectiveness of immersion solutions to reduce the microbial growth on dental prostheses

This investigation evaluated the effectiveness of an infection control protocol for cleansing and disinfecting removable dental prostheses. Sixty-four dentures were rubbed with sterile cotton swab immediately after they had been taken from patients' mouths. Samples were individually placed in the culture medium and immediately incubated at 37 +/- 2 degreesC. The dentures were scrubbed for 1 min with 4% chlorhexidine, rinsed for 1 min in sterile water and placed for 10 min in one of the following immersion solutions: 4% chlorhexidine gluconate, 1% sodium hypochlorite, Biocide (iodophors) and Amosan (alkaline peroxide). After the disinfection procedures, the dentures were immersed in sterile water for 3 min, reswabbed and the samples were incubated. All samples obtained in the initial culture were contaminated with micro-organisms. All the lower dentures immersed in Biocide showed positive growth, and the upper dentures were positive for growth in six of eight dentures. The 4% chlorhexidine gluconate, 1% sodium hypochlorite and Amosan solutions have been proved effective to reduce the growth of the micro-organisms in the 10 min immersion period. The protocol evaluated in this study seems to be a viable method to prevent cross-contamination between dental personnel and patients.

Differences in metabolic and inflammatory responses in lower and upper body high-intensity intermittent exercise

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of temperature on salt-salt aqueous biphasic systems: manifestations of upper critical solution temperature

Water-miscible ionic liquids (ILs) may be salted out using kosmotropic salts such as potassium phosphate (K3PO4) to form salt-salt aqueous biphasic systems (ABS). The effect of temperature on these systems has been studied using phase diagrams and it is observed that the degree of binodal shift decreases (requiring lower IL and kosmotropic salt concentrations) with the increase of temperature following the trend [C(4)mim]Cl > [C(4)py]Cl > [C(4)mmim] Cl > [N-4444]Cl. This trend can be correlated with the decreasing hydrogen bonding abilities of each salt. The phase behavior was also interpreted on the basis of critical solution temperature behavior of pure aqueous ionic liquid solutions. Additionally, the distribution of alcohols in these systems was studied as a function of temperature and it was found that the distribution ratios did not change with changes in temperature. The Gibbs energy of transfer of a methylene group in these systems and correlation to tie-line length was also determined. It was concluded that while the miscibility of alcohols increases in the ILs with increasing temperature, phase divergence in the aqueous biphasic system decreases, and thus these competing forces tend to cancel each other out for small polar molecules. A comparison is provided for the response to temperature in the currently studied salt-salt systems and analogous ABS formed by the addition of hydrophilic polymers to kosmotropic salts (polymer-salt) or other polymers (polymer-polymer).

Aircraft-based in-situ aerosol mass spectrometry: Chemical characterization and source identification of submicron particulate matter in the free and upper troposphere and lower stratosphere

The composition of the atmosphere is frequently perturbed by the emission of gaseous and particulate matter from natural as well as anthropogenic sources. While the impact of trace gases on the radiative forcing of the climate is relatively well understood the role of aerosol is far more uncertain. Therefore, the study of the vertical distribution of particulate matter in the atmosphere and its chemical composition contribute valuable information to bridge this gap of knowledge. The chemical composition of aerosol reveals information on properties such as radiative behavior and hygroscopicity and therefore cloud condensation or ice nucleus potential. rnThis thesis focuses on aerosol pollution plumes observed in 2008 during the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) campaign over Greenland in June/July and CONCERT (Contrail and Cirrus Experiment) campaign over Central and Western Europe in October/November. Measurements were performed with an Aerodyne compact time-of-flight aerosol mass spectrometer (AMS) capable of online size-resolved chemical characterization of non-refractory submicron particles. In addition, the origins of pollution plumes were determined by means of modeling tools. The characterized pollution episodes originated from a large variety of sources and were encountered at distinct altitudes. They included pure natural emissions from two volcanic eruptions in 2008. By the time of detection over Western Europe between 10 and 12 km altitude the plume was about 3 months old and composed to 71 % of particulate sulfate and 21 % of carbonaceous compounds. Also, biomass burning (BB) plumes were observed over Greenland between 4 and 7 km altitude (free troposphere) originating from Canada and East Siberia. The long-range transport took roughly one and two weeks, respectively. The aerosol was composed of 78 % organic matter and 22 % particulate sulfate. Some Canadian and all Siberian BB plumes were mixed with anthropogenic emissions from fossil fuel combustion (FF) in North America and East Asia. It was found that the contribution of particulate sulfate increased with growing influences from anthropogenic activity and Asia reaching up to 37 % after more than two weeks of transport time. The most exclusively anthropogenic emission source probed in the upper troposphere was engine exhaust from commercial aircraft liners over Germany. However, in-situ characterization of this aerosol type during aircraft chasing was not possible. All long-range transport aerosol was found to have an O:C ratio close to or greater than 1 implying that low-volatility oxygenated organic aerosol was present in each case despite the variety of origins and the large range in age from 3 to 100 days. This leads to the conclusion that organic particulate matter reaches a final and uniform state of oxygenation after at least 3 days in the free troposphere. rnExcept for aircraft exhaust all emission sources mentioned above are surface-bound and thus rely on different types of vertical transport mechanisms, such as direct high altitude injection in the case of a volcanic eruption, or severe BB, or uplift by convection, to reach higher altitudes where particles can travel long distances before removal mainly caused by cloud scavenging. A lifetime for North American mixed BB and FF aerosol of 7 to 11 days was derived. This in consequence means that emission from surface point sources, e.g. volcanoes, or regions, e.g. East Asia, do not only have a relevant impact on the immediate surroundings but rather on a hemispheric scale including such climate sensitive zones as the tropopause or the Arctic.

Surgical treatment of upper, middle and lower cervical injuries and non-unions by anterior procedures

The goals of any treatment of cervical spine injuries are: return to maximum functional ability, minimum of residual pain, decrease of any neurological deficit, minimum of residual deformity and prevention of further disability. The advantages of surgical treatment are the ability to reach optimal reduction, immediate stability, direct decompression of the cord and the exiting roots, the need for only minimum external fixation, the possibility for early mobilisation and clearly decreased nursing problems. There are some reasons why those goals can be reached better by anterior surgery. Usually the bony compression of the cord and roots comes from the front therefore anterior decompression is usually the procedure of choice. Also, the anterior stabilisation with a plate is usually simpler than a posterior instrumentation. It needs to be stressed that closed reduction by traction can align the fractured spine and indirectly decompress the neural structures in about 70%. The necessary weight is 2.5 kg per level of injury. In the upper cervical spine, the odontoid fracture type 2 is an indication for anterior surgery by direct screw fixation. Joint C1/C2 dislocations or fractures or certain odontoid fractures can be treated with a fusion of the C1/C2 joint by anterior transarticular screw fixation. In the lower and middle cervical spine, anterior plating combined with iliac crest or fibular strut graft is the procedure of choice, however, a solid graft can also be replaced by filled solid or expandable vertebral cages. The complication of this surgery is low, when properly executed and anterior surgery may only be contra-indicated in case of a significant lesion or locked joints.

Imaging appearances of Buerger's disease complications in the upper and lower limbs

Thromboangiitis obliterans (Buerger's disease) is a rare, non-atherosclerotic, segmental, inflammatory vasculitis that most commonly involves small and medium-sized arteries, veins and nerves of the extremities and affects tobacco smokers between the ages of 25 and 45 years. The manifestations of Buerger's disease can be extremely variable and, therefore, awareness of the condition is important for both general and musculoskeletal radiologists. This paper presents the radiological appearance of the sequelae of Buerger's disease involving the upper and lower limbs.