Variational principle and a perturbative solution of non-linear string equations in curved space

String dynamics in a curved space-time is studied on the basis of an action functional including a small parameter of rescaled tension $\epsilon=\gamma/\alpha^{\prime}$, where $\gamma$ is a metric parametrizing constant. A rescaled slow worldsheet time $T=\epsilon\tau$ is introduced, and general covariant non-linear string equation are derived. It is shown that in the first order of an $\epsilon$-expansion these equations are reduced to the known equation for geodesic derivation but complemented by a string oscillatory term. These equations are solved for the de Sitter and Friedmann -Robertson-Walker spaces. The primary string constraints are found to be split into a chain of perturbative constraints and their conservation and consistency are proved. It is established that in the proposed realization of the perturbative approach the string dynamics in the de Sitter space is stable for a large Hubble constant $H (\alpha^{\prime}H^{2}\gg1)$.Comment: 22 pages, LATEX, no figure

Multiple Metastases of a Transmissible Venereal Tumor in a Dog

Background: Transmissible venereal tumor (TVT) is a common contagious neoplasm in dogs that spreads through coitus. Extra-genital presentations of this tumor are frequent and usually develop through implantation of neoplastic cells on exposed mucosae. TVT metastasis is rare, and when it happens it’s usually affecting regional lymph nodes and adjacent cutaneous tissue.Case: A female mixed breed dog, with estimated age of 7 to 11-month-old, was rescued from the streets and taken to a veterinary clinic in the city of Porto Alegre, RS. The animal had multiple nodules on its body, vulva, ocular mucosa, and gingiva, along with signs of malnutrition and apathy. Cytological examination of the nodules and vulva was done and yielded a cytologic picture compatible with TVT.  Weakly treatment with 0.3 mg/m² vincristine sulphate was used until clinical cure was noted. Approximately two weeks after clinical cure, the dog showed a blue colored eye and was referred for ophthalmological, where it was diagnosed with vision loss due to glaucoma secondary to a neoplasm. The eye was then removed and sent for histopathological evaluation. Histopathology of the eye was compatible with TVT diagnosis. One month after enucleation the animal display dispenia, pain, aggressiveness and epistaxis. The animal was euthanized and submitted for post-mortem evaluation. At necropsy there was a well-defined grayish-white, nodule near the thalamus. Similar nodules were also found on the lung, and anterior chamber of the eye. Histologically, all the nodules were compatible with TVT. Immunohistochemical examination was done, with the neoplastic cells being positive for vimentin and negative for cytokeratin, CD79a, CD3 and CD117. Based on the post-mortem examination and clinical history, diagnosis of TVT was given.Discussion: The clinical manifestation of the tumor in the genitalia presented by the animal is characteristic of TVT, but the extragenital presentation is less common. Although extragenital manifestations are well reported, most are due to auto-implantation (contact with the dog’s own genitalia) or hetero-implantation (contact with the genitalia of another dog). Metastases originating from the genitalia are markedly less common (5% of cases), and when they occur, they usually affect regional lymph nodes due to lymphatic communication. However, they can also occur in other organs, such as the liver, kidneys, spleen, tonsils, skin and subcutaneous tissue, bone, CNS, mesentery, and eyes. In this case, it is difficult to determine if the ocular tumor reported was due to metastasis or implantation by direct eye contact with TVT cells, since the animal lived on the street, and it was not possible to establish a more accurate history. The dog in this study was treated with vincristine sulfate; however, the treatment was stopped after one month, when no signs of the tumor were observed. Treatment with vincristine is the method of choice for TVT, since it is highly effective. However, rare cases of recurrence after treatment may occur. In addition, this drug does not cross the blood-brain barrier, and this may have favored the rapid reappearance of the tumor after treatment. The metastases from TVT to the CNS are extremely rare, with only a few cases reported in the literature. However, the possibility of metastases in animals with neurological and historical signs of TVT should be considered in the diagnosis. This case draws attention to the occurrence of TVT in the CNS of dogs with ocular TVT

Phase behavior of (polyacrylamides + water) solutions: concentration, pressure and isotope effects

Phase diagrams of poly(N-isopropylacrylamide) (PNIPAAM) as well as of hydrophilically-modified copolymers in aqueous solution were determined. A high-accuracy He-Ne Laser scattering technique was used for the detection of operational spinodal (sp) and cloud-point (cp) curves. Polymer concentration was varied from 0.5 to 20 wt.%. In the case of copoly(PNIPAAM/vinylsaccharide) several different chain lengths were considered. Pressure (up to 400 bar) and solvent isotope effects were studied. We predict a closed-loop type phase diagram for the copolymers, which presents an estimated hypercritical point in H2O solutions at Mw~0.5×105, although only lower critical solution temperature (LCST) is experimentally accessible. At lower molecular weights, the solutions are always in the one-phase region.http://www.sciencedirect.com/science/article/B6TG2-43MC9F5-N/1/63fb7dd8bec4ff798723b9bcb318a0a

Ethical challenges in care for older patients who resist help

Abstract Background: Situations where patients resist necessary help can be professionally and ethically challenging for health professionals, and the risk of paternalism, abuse and coercion are present. Research question: The purpose of this study was to examine ethical challenges in situations where the patient resists healthcare. Research design: The method used was clinical application research. Academic staff and clinical coresearchers collaborated in a hermeneutical process to shed light on situations and create a basis for new action. Participants and research context: Four research groups were established. Each group consisted of six to eight clinical co-researchers, all employees with different health profession backgrounds and from different parts of the municipal healthcare services, and two scientific researchers. Ethical considerations: The study was conducted in compliance with ethical guidelines and principles. Participants were informed that participation was voluntary and that confidentiality would be maintained. They signed a consent form. Findings: The findings showed that the situations where patients opposed help related to personal hygiene, detention in an institution and medication associated with dental treatment. The situations were perceived as demanding and emotionally stressful for the clinicians. Discussion: The situations can be described as everyday ethics and are more characterised by moral uncertainty and moral distress than by being classic ethical dilemmas. Conclusion: Norwegian legislation governing the use of force seems to provide decision guidance with the potential to reduce uncertainty and moral stress if the clinicians' legal competence had been greater

Environmental Exposure of the Mouse Germ Line: DNA Adducts in Spermatozoa and Formation of De Novo Mutations during Spermatogenesis

Background: Spermatozoal DNA damage is associated with poor sperm quality, disturbed embryonic development and early embryonic loss, and some genetic diseases originate from paternal de novo mutations. We previously reported poor repair of bulky DNA-lesions in rodent testicular cells. Methodology/Principal Findings: We studied the fate of DNA lesions in the male germ line. B[a]PDE-N 2-dG adducts were determined by liquid chromatography-tandem mass spectrometry, and de novo mutations were measured in the cIItransgene, in Big BlueHmice exposed to benzo[a]pyrene (B[a]P; 3650 mg/kg bw, i.p.). Spermatozoa were harvested at various time-points following exposure, to study the consequences of exposure during the different stages of spermatogenesis. B[a]PDE-N 2-dG adducts induced by exposure of spermatocytes or later stages of spermatogenesis persisted at high levels in the resulting spermatozoa. Spermatozoa originating from exposed spermatogonia did not contain DNA adducts; however de novo mutations had been induced (p = 0.029), specifically GC-TA transversions, characteristic of B[a]P mutagenesis. Moreover, a specific spectrum of spontaneous mutations was consistently observed in spermatozoa. Conclusions/Significance: A temporal pattern of genotoxic consequences following exposure was identified, with an initial increase in DNA adduct levels in spermatozoa, believed to influence fertility, followed by induction of germ line de nov