192 research outputs found

    2D fermion on the strip with boundary defects as a CFT with excited spin fields

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    We consider a two-dimensional fermion on the strip in the presence of an arbitrary number of zero-dimensional boundary changing defects. We show that the theory is still conformal with time dependent stress-energy tensor and that the allowed defects can be understood as excited spin fields. Finally we compute correlation functions involving these excited spin fields without using bosonization

    Morpho-sedimentary evolution of a microtidal meandering channel driven by 130-years of natural and anthropogenic modifications of the Venice Lagoon (Italy)

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    Abstract Tidal channels form the pathways for tidal currents to propagate and distribute clastic sediments and nutrients, thus providing a primary control on tidal-landscape ecomorphodynamics. Most tidal channels in both estuarine and lagoonal environments have a tendency to meander, yet very few studies exist that investigate the full spectrum of processes controlling tidal meander morpho-sedimentary evolution. The Venice Lagoon (Italy) offers a unique opportunity to shed light on this topic, because a long record of morphological and sedimentary data is available, which allows one to relate tidal channel evolution to the hydrodynamic and morphological changes undergone by the lagoon. In particular, during the last 130 years, feedback between rising relative sea levels and anthropogenic interventions have caused severe modifications of the Lagoon hydro- and morpho-dynamics. Here we investigate how these modifications fed back into the morpho-sedimentary evolution of a meandering tidal channel located in the northern Lagoon. Combining extensive datasets of aerial photographs, topographic and bathymetric surveys, geophysical investigations, sedimentary core analysis, and numerical modeling, we show that enhanced local tidal ranges and water discharges determine adjustments of channel cross-sectional geometries proportional to increasing tidal prisms, while changes in local tidal asymmetries caused modifications of the local sediment transport regime, resulting in the development of bar-pool patterns according to the dominant tidal phase. Such bar-pool patterns eventually determine channel migration through a bar-push mechanism controlled by a fluvial-like, quasi-linear relationship between local channel curvature and lateral migration rates. Critical differences in sediment transport regime are however highlighted between fluvial and tidal meanders, the latter being potentially characterized by high concentrations of suspended sediment during periods of slack waters when wind-driven sediment transport processes are not negligible. This could hamper the formation of high-relief bedforms, with profound implications for the sedimentology of tidal point-bar deposits

    Ultrasound-guided hook-wire localization for surgical excision of non-palpable superficial inguinal lymph nodes in dogs: A pilot study

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    The evaluation of loco-regional lymph nodes (LN) plays an important prognostic role and assists the clinical decision making in canine cancer patients. Excision of non-palpable LN can be challenging. The aim of the study was to evaluate surgical time, successful excision rate and surgical complications associated with the use of an ultrasound-guided hook-wire (UGHW) LN localization method for non-palpable superficial inguinal LN (SILN) in dogs. Dogs that presented for excision of non-palpable SILN, performed with the aid of an UGHW placement, were enrolled. Information including signalment, SILN width, UGHW placement and surgical procedure time, hook-wire position, successful excision and intra-and post-operative complications were reviewed. Seventeen dogs were enrolled. Median LN width was 3 mm (range 2–11). Median time of preoperative UGHW placement and surgical LN excision was 8 min and 15 min, respectively. Successful SILN excision was achieved in all cases. Two minor intra-operative (hook migration and wire fragmentation) and one minor post-operative complications (seroma) were observed. No major intraoperative or post-operative complications occurred. The UGHW LN localization method is safe and effective and may allow a high rate of successful SILN excisions in dogs. This method has the potential to facilitate LN excision for other superficial LN locations

    Mast cell tumours in less than 12 months of age: a multi-institutional retrospective study

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    Objectives: To describe the clinicopathological and genetic characteristics of mast cell tumours in dogs less than 12 months old. Materials and methods: Retrospective review of dogs aged less than 12 months when diagnosed with mast cell tumours at three referral hospitals in the UK. Results: Sixteen pure-bred dogs were included, of which 11 were female. The median age at first presentation and diagnosis were 7.6 and 9 months, respectively. In 13 dogs the mast cell tumours were cutaneous and in three they were subcutaneous. Four cutaneous mast cell tumours were described as high-grade (Patnaik or Kiupel) and nine were Patnaik grade II; three had mitotic index of >5 in 10 high-power fields. Of the three subcutaneous tumours, two had an infiltrative growth pattern and one had mitotic index of 10 per 10 high-power fields. Of 10 tested dogs, seven had c-kit mutations in exon 11 and Ki-67 score was above the cut-off value in nine. Four of 12 cases showed evidence of metastasis in the regional lymph nodes. After varying treatment protocols, all patients were alive and disease free at a median of 1115 days after diagnosis. Clinical significance: The prognosis of mast cell tumours in dogs less than a year old appears better than the adult counterparts, even without extensive treatment

    MALASSEZIA, MITES AND BACTERIA IN THE EXTERNAL EAR CANAL OF DOGS AND CATS WITH OTITIS EXTERNA

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    Occurrence of Malassezia, mites and bacteria, was evaluated through cytology, culture and microscopical analysis of auricular cerumen collected from 115 cats and 203 dogs with otitis externa. For the dentification of Malassezia species, a PCR-based technique was also used. All the patients enrolled in the study were examined for Malassezia and all cats and 101 dogs were also investigated for mites. Bacteriological examination was performed on 16 cats and 60 dogs. The associations between Malassezia and the other pathogens and the correlations between Malassezia and season, gender and ear conformation, were evaluated. Malassezia pachydermatis was isolated from 58.2% cats and 52.7% dogs, while Otodectes cynotis was identified in 66.1% cats and in 5.9% dogs. Bacteria were detected in 18.7% cats and 36.7% dogs and Staphylococcus pseudointermedius, Staphylococcus epidermidis, Pseudomonas aeruginosa, Streptococcus canis, Escherichia coli and Bacillus sp. were identified. M. pachydermatis was isolated in pure culture from 28.3% cats and from 87.1% dogs, while it was associated with O. cynotis in 70.1% of cats and in 5% of dogs, and with bacteria in 1.5% of cats and 23.3% of dogs. Mixed infections caused by M. pachydermatis, bacteria (S. pseudointermedius) and mites occurred in 1 cat and 1 dog. Our results suggest that ear conformation is an important individual predisposing factor for Malassezia otitis in dogs and indicated the influence of the season on onset of Malassezia infections in cats

    Direct Mott Insulator-to-Superfluid Transition in the Presence of Disorder

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    We introduce a new renormalization group theory to examine the quantum phase transitions upon exiting the insulating phase of a disordered, strongly interacting boson system. For weak disorder we find a direct transition from this Mott insulator to the Superfluid phase. In d > 4 a finite region around the particle-hole symmetric point supports this direct transition, whereas for 2=< d <4 perturbative arguments suggest that the direct transition survives only precisely at commensurate filling. For strong disorder the renormalization trajectories pass next to two fixed points, describing a pair of distinct transitions; first from the Mott insulator to the Bose glass, and then from the Bose glass to the Superfluid. The latter fixed point possesses statistical particle-hole symmetry and a dynamical exponent z, equal to the dimension d.Comment: 4 pages, Latex, submitted to Physical Review Letter

    Dimensional crossover of a boson gas in multilayers

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    We obtain the thermodynamic properties for a non-interacting Bose gas constrained on multilayers modeled by a periodic Kronig-Penney delta potential in one direction and allowed to be free in the other two directions. We report Bose-Einstein condensation (BEC) critical temperatures, chemical potential, internal energy, specific heat, and entropy for different values of a dimensionless impenetrability P0P\geqslant 0 between layers. The BEC critical temperature TcT_{c} coincides with the ideal gas BEC critical temperature T0T_{0} when P=0P=0 and rapidly goes to zero as PP increases to infinity for any finite interlayer separation. The specific heat CVC_{V} \textit{vs} TT for finite PP and plane separation aa exhibits one minimum and one or two maxima in addition to the BEC, for temperatures larger than TcT_{c} which highlights the effects due to particle confinement. Then we discuss a distinctive dimensional crossover of the system through the specific heat behavior driven by the magnitude of PP. For T<TcT<T_{c} the crossover is revealed by the change in the slope of logCV(T)\log C_{V}(T) and when T>TcT>T_{c}, it is evidenced by a broad minimum in CV(T)C_{V}(T).Comment: Ten pages, nine figure

    Timing of adjuvant chemotherapy after limb amputation and effect on outcome in dogs with appendicular osteosarcoma without distant metastases

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    Objective: To determine an optimal time interval between amputation and initiation of adjuvant chemotherapy (TIamp-chemo) in dogs with appendicular osteosarcoma without distant metastases and whether TIamp-chemo was associated with outcome. Animals: 168 client-owned dogs treated at 9 veterinary oncology centers. Procedures: Data were collected from the dogs' medical records concerning potential prognostic variables and outcomes. Dogs were grouped as to whether they received chemotherapy within 3, 5, 7, 10, 15, 20, 30, or &gt; 30 days after amputation of the affected limb. Analyses were performed to identify variables associated with time to tumor progression and survival time after limb amputation and to determine an optimal TIamp-chemo. Results: Median TIamp-chemo was 14 days (range, 1 to 210 days). Median time to tumor progression for dogs with a TIamp-chemo ≤ 5 days (375 days; 95% CI, 162 to 588 days) was significantly longer than that for dogs with a TIamp-chemo &gt; 5 days (202 days; 95% CI, 146 to 257 days). Median overall survival time for dogs with a TIamp-chemo ≤ 5 days (445 days; 95% CI, 345 to 545 days) was significantly longer than that for dogs with a TIamp-chemo &gt; 5 days (239 days; 95% CI, 186 to 291 days). Conclusions and clinical relevance: Findings indicated that early (within 5 days) initiation of adjuvant chemotherapy after limb amputation was associated with a significant and clinically relevant survival benefit for dogs with appendicular osteosarcoma without distant metastases. These results suggested that the timing of chemotherapy may be an important prognostic variabl

    Outcome comparison between radiation therapy and surgery as primary treatment for dogs with periarticular histiocytic sarcoma: An Italian Society of Veterinary Oncology study

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    Localized histiocytic sarcoma may occur as a primary lesion in periarticular tissues of large appendicular joints. Treatment options for the primary lesion include radical surgical excision, radiation therapy (RT), or both, in combination with chemotherapy for potential systemic metastases. In an effort to better characterize the time to progression (TTP) following surgical vs non-surgical approaches for periarticular histiocytic sarcoma (PAHS), a contemporary European population of affected dogs was retrospectively surveyed. Medical records were queried for newly-diagnosed PAHS cases undergoing surgery (predominantly limb amputation) or RT followed by systemic chemotherapy. Of 49 dogs, 34 underwent RT and 15 underwent surgery. All dogs received adjuvant chemotherapy. There was no statistically significant difference in TTP or overall survival between groups. The median TTP was 336 days for the operated dogs and 217 days for the irradiated dogs (P =.117). The median overall survival time was 398 days for the operated dogs and 240 days for the irradiated dogs (P =.142). On multi-variable analysis, the variables significantly associated with an increased risk of both tumour progression and tumour-related death were regional lymph node and distant metastasis at admission. Survival and local control rates following RT may be comparable to radical resection. These data may better inform shared decision-making processes between multi-disciplinary care providers and owners
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