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Nonlinear dynamic fracture problems with polynomial and strain-limiting constitutive relations [article]

Victoria Patel
2021 arXiv   pre-print
We extend the framework of dynamic fracture problems with a phase-field approximation to the case of a nonlinear constitutive relation between the Cauchy stress tensor 𝕋, linearised strain ϵ(𝐮) and strain rate ϵ(𝐮_t ). The relationship takes the form ϵ(𝐮_t) + αϵ(𝐮) = F(𝕋) where F satisfies certain p-growth conditions. We take particular care to study the case p=1 of a 'strain-limiting' solid, that is, one in which the strain is bounded a priori. We prove the existence of long-time, large-data
more » ... ak solutions of a balance law coupled with a minimisation problem for the phase-field function and an energy-dissipation inequality, in any number d of spatial dimensions. In the case of Dirichlet boundary conditions, we also prove the satisfaction of an energy-dissipation equality.
arXiv:2108.03896v1 fatcat:fj2pfc4jsvat5nxo5jptjadjum

Chitosan against cutaneous pathogens

Jackson Champer, Julie Patel, Nathalie Fernando, Elaheh Salehi, Victoria Wong, Jenny Kim
2013 AMB Express  
Two common cutaneous pathogens, Propionibacterium acnes and Staphylococcus aureus, have increasingly developed resistance to frontline antibiotics (Song et al. 2011; Patel et al. 2010; Jappe et al. 2008  ... 
doi:10.1186/2191-0855-3-37 pmid:23829873 pmcid:PMC3720194 fatcat:6mu5jtbho5fvfbligmcqbpl6oq

The role of oral bacteria in COVID-19

Jay Patel, Victoria Sampson
2020 The Lancet Microbe  
doi:10.1016/s2666-5247(20)30057-4 pmid:32835339 pmcid:PMC7333982 fatcat:njtdjjkkfrggxico22vewx7dde

Pediatric tibial shaft fractures

Varatharaj Mounasamy, NiravK Patel, Joanna Horstman, Victoria Kuester, Senthil Sambandam
2018 Indian Journal of Orthopaedics  
., hemophilia) Open fractures Associated neurovascular injury Patel, et al.: Pediatric tibial shaft fractures  ... 
doi:10.4103/ortho.ijortho_486_17 pmid:30237610 pmcid:PMC6142797 fatcat:kxkimndkhbahnisksgb7juqbvy

Clinical correlates of blood-derived circulating tumor DNA in pancreatic cancer

Hitendra Patel, Ryosuke Okamura, Paul Fanta, Charmi Patel, Richard B. Lanman, Victoria M. Raymond, Shumei Kato, Razelle Kurzrock
2019 Journal of Hematology & Oncology  
(The rate of tissue TP53 alterations was 76% [19 of 25] for metastatic sites and 78% [32 of 41] for primary sites; for KRAS alterations, it was 84% [21 of 25] versus 95% Patel et al.  ... 
doi:10.1186/s13045-019-0824-4 pmid:31801585 pmcid:PMC6894333 fatcat:xkghxwjojnhilhyasovaqcy7pa

Rivaroxaban in acute venous thromboembolism: UK prescribing experience

Victoria Speed, Jignesh P. Patel, Derek Cooper, Stephen Miller, Lara N. Roberts, Raj K. Patel, Roopen Arya
2021 Research and Practice in Thrombosis and Haemostasis  
Rivaroxaban was reported as effective as traditional therapies for the acute treatment of venous thromboembolism (VTE) with fewer major bleeding complications in the seminal Einstein program and is now a recommended option for the treatment of VTE around the world. To report the safety and efficacy of rivaroxaban in daily care for the management of acute VTE in the United Kingdom. The FIRST registry is a UK-only, multicenter, noninterventional, observational VTE study (NCT02248610). Consecutive
more » ... patients diagnosed with acute VTE, managed with rivaroxaban, were recruited and followed for up to 5 years. The primary outcomes were treatment-emergent symptomatic objectively diagnosed recurrent VTE, major and clinically relevant nonmajor bleeding (CRNMB), and all-cause mortality. A total of 1262 participants were recruited between 2014 and 2018. Participants were heterogeneous, with age range 18 to 95 years, weight 35 to 234 kg, and maximum body mass index 64.4 kg/m2. The median duration of treatment exposure was 135 days (interquartile range [IQR], 84-307) and overall follow-up 497 days (IQR, 175-991). There were seven episodes of symptomatic VTE recurrence, 0.6%, (0.74/100 patient-years; 95% confidence interval [CI], 0.19-1.28). There were 79 of 1239 (6.4%), 8.66 of 100 patient-years (95% CI, 6.90-10.73) first episodes of major or CRNMB, which were most frequently reported by women aged <50 years as abnormal vaginal bleeding. Rivaroxaban is an effective and safe single drug modality for the treatment of VTE in daily practice in the United Kingdom. Data to determine the optimal anticoagulation therapy for women of childbearing age are needed.
doi:10.1002/rth2.12607 pmid:34723054 pmcid:PMC8531140 fatcat:jxz2ory5wbfllofl2aamaujdti

Topical clobetasol for the treatment of toxic epidermal necrolysis: study protocol for a randomized controlled trial

Reason Wilken, Chin Shang Li, Victoria R. Sharon, Kyoungmi Kim, Falin B. Patel, Forum Patel, Emanual Maverakis
2015 Trials  
Toxic epidermal necrolysis (TEN) is a rare systemic allergic drug eruption with high patient mortality. Currently, no established treatments have been shown to be effective for TEN beyond supportive care. Prior studies of systemic corticosteroids have yielded conflicting data, with some showing a possible benefit and others reporting in increased mortality. However, topical steroids have shown promise for treatment of ocular sequelae of TEN, such as scarring and vision loss. We have designed a
more » ... andomized controlled trial to evaluate topical clobetasol for treatment of the epidermal manifestations of TEN. In addition, we propose genetic studies to characterize the TEN transcriptome and alterations in cutaneous gene expression that might occur following topical steroid treatment. Methods/Design: This split-body randomized, double-blind, placebo-controlled Phase IIa proof-of-concept trial will evaluate the safety and efficacy of once-daily topical clobetasol applied to the skin of patients with TEN. This multicenter trial will recruit a total of 15 patients between the ages of 12 and 85 from the University of California Davis Medical Center and Shriners Hospital for Children inpatient burn units. Designated treatment areas on opposite sides of the body will be treated with blinded clobetasol 0.05 % ointment or control petrolatum ointment daily for 14 days. On day 3 of therapy, a biopsy will be taken from the treated area for genetic studies. The primary study aims will be to establish the safety of topical clobetasol treatment and determine the time to cessation of skin detachment for the control and clobetasol-treated areas. Secondary endpoints will evaluate efficacy using parameters such as time to 90 % re-epithelialization and percentage of affected skin at 0, 3, 6, 9, 12 and 15 days. Genomic DNA and RNA will be obtained from biopsy samples, to characterize the TEN transcriptome and identify changes in gene expression after topical steroid treatment. Discussion: Topical steroids have shown promise for treating ocular complications of TEN, but to date have not been evaluated for cutaneous manifestations of the disease. This trial will investigate clinical and molecular outcomes of topical clobetasol application and hopefully provide insight into the disease pathophysiology. Trial registration: NCT02319616.
doi:10.1186/s13063-015-0879-7 pmid:26297574 pmcid:PMC4546316 fatcat:745ukiqvrjhhrgrntu56m3cs6y

Multimodal therapy of idiopathic pyoderma gangrenosum

Victoria Sharon, Barbara Burrall, Forum Patel, Yong He, Thomas Konia, Itzel Bustos Villalobos, Emanual Maverakis
2014 Dermatology Online Journal  
A 13-year old girl was admitted to the University of California Davis Medical Center for evaluation and treatment of cutaneous bullae and ulcerations over her lower extremities that were refractory to antibiotic therapy and incision and drainage. Her disease continued to worsen with the appearance of multiple new bullae and the progression of old ones into deep ulcers with undermined borders. Biopsy revealed a neutrophilic dermatosis and diagnostic work-up was negative for infectious or
more » ... ne etiologies. Given her clinical presentation, biopsy results, and negative work-up, a diagnosis of pyoderma gangrenosum (PG) was made and she was started on immunosuppressive medications. The patient was started on a multidrug regimen of prednisone and cyclosporine but remission was not achieved until the addition of adalimumab. After the inflammatory component of her disease was under control, wound care measures were maximized to promote ulcer healing. Wound care measures included compression and debridement. Upon complete closure of all wounds she was successfully transitioned to mycophenolate mofetil monotherapy for maintenance therapy. This case emphasizes the need for combinational therapy to successfully treat severe cases of PG, which are often refractory to monotherapy with prednisone or cyclosporine. It also highlights the importance of appropriate wound care to achieve complete ulcer healing. A previously healthy, 13-year old girl presented to the University of California, Davis Emergency Room with a history of lower extremity cutaneous bullae. Her first bulla was noted five days prior on her right lower extremity. She was initially treated by an outside emergency room for a presumptive abscess with incision and drainage followed by oral amoxicillin/clavulanate and trimethoprim/sulfamethoxazole. Over the next few days, she developed a fever (maximum temperature of 101.4 degrees Fahrenheit), tachycardia (120 beats per minute), arthralgia, and multiple new bullae over her upper and lower extremities. She was subsequently admitted to the UC Davis Medical Center for I.V. antibiotic therapy (clindamycin and vancomycin) and surgical debridement. During the following 48 hours, several of the debrided nodules enlarged in width and depth, forming large putrid ulcerations ( Figure 1A and 1B) . The patient denied any constitutional symptoms of fatigue, abdominal pain, constipation, emesis, oral ulcers, loose stool, melena, or hematochezia.
doi:10.5070/d3206022856 fatcat:5c3wurk2tja7lkv7gsr76uiov4

Regulation of eotaxin-3/CCL26 expression in human monocytic cells

Victoria E. L. Stubbs, Christopher Power, Kamala D. Patel
2010 Immunology  
Patel and Dr C. Power are both Canada Research Chairs. KDP is an Alberta Heritage Foundation for Medical Research Scientist and CP is an AHFMR Senior Scholar. Dr V.E.L.  ... 
doi:10.1111/j.1365-2567.2009.03214.x pmid:20059579 fatcat:6o3w6qgfajfjtg3ghxjbaheczi

Clostridium tertium bacteremia and hepatic abscess in a non-neutropenic patient

Victoria Milano, Lauren Biehle, Shalvi Patel, John Hammer
2019 IDCases  
Patel, and Dr. Hammer Roles/Writingoriginal draft: Dr. Milano, Dr. Biehle, Dr. Patel Writingreview & editing: Dr. Milano, Dr. Biehle, Dr. Patel, and Dr. Hammer.  ...  Patel, and Dr. Hammer Data curation: Dr. Milano, Dr. Biehle, Dr. Patel, and Dr. Hammer Investigation: Dr. Milano and Dr. Biehle Methodology: Dr. Milano, Dr. Biehle, Dr. Patel, and Dr.  ... 
doi:10.1016/j.idcr.2019.e00510 pmid:30976516 pmcid:PMC6441761 fatcat:eicikq75ivh2jadznmmy6uo7bi

Structural Effects of Lanthanide Dopants on Alumina

Ketan Patel, Victoria Blair, Justin Douglas, Qilin Dai, Yaohua Liu, Shenqiang Ren, Raymond Brennan
2017 Scientific Reports  
Lanthanide (Ln 3+ ) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO 3 , Ln 2 O 3 ), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of
more » ... transformation and enables phase population control, which is achieved without the formation of new phases. The delay in phase transition (θ → α), and alteration of powder morphology, particle dimensions, and composition ratios between αand θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)-and lutetium (Lu)-doped alumina. This study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications. Aluminum oxide (Al 2 O 3 ), also known as alumina, is a common ceramic material of interest for advanced applications. Apart from the most thermodynamically stable α -phase, alumina also exists in several metastable/ transitional phases 1 . These metastable phases are classified into two major categories, including face centered cubic (FCC) and hexagonal closed packing (HCP) anionic arrangements 2 . These polymorphs depend on the arrangement of cations within each oxygen sub-group. The existence of several crystalline polymorphs and vacant octahedral sites enables alumina to be adopted for a variety of doping studies and technological applications 3-5 . Lanthanide (Ln 3+ ) ion-doped Al 2 O 3 is particularly appealing, since the local environment of the doped ions is known to critically influence the optical and mechanical properties of Al 2 O 3 due to the large size mismatch between Ln dopants and aluminum 6-8 . For example, the presence of dopants (ytterbium, gadolinium or lanthanum) strengthens the grain boundaries of alumina, largely affecting the mechanical properties 9-11 . A study conducted on doping alumina with lanthanum (La) showed a reduction in the phase transformation (γ → α ) temperature by 100 °C, thus increasing the thermal stability of γ -Al 2 O 3 12 . Although Ln doping has shown favorable effects on alumina, understanding the dopant location within the alumina matrix remains a challenge. Due to the large size of the Ln-ions compared to Al 3+ (0.054 nm for Al 3+ and 0.103 nm → 0.0861 nm for Ln 3+ series), which results in an ionic size mismatch between the dopants (Ln 3+ ) and the Al 3+ cations, the solubility of lanthanide cations in alumina is a significant challenge 13,14 . Additionally, there is a limited understanding of the local structures and distributions of Ln-ions within the alumina matrix [15] [16] [17] [18] [19] . Previous reports on Ln-doping of alumina have generally been conducted at doping concentrations of 0.5-5 wt% 20-25 . The formation of a new phase, LnAlO 3 or Ln 2 O 3 , is observed in previously reported cases, which complicates understanding of the role Ln-doping plays on structure and phase transition of the alumina lattice 26,27 . This also makes it intriguing to assess the role of other Ln-elements as "structural promoters" due to their phase transformation delays and resulting effects on the structure of doped alumina. lattice. The formation of 100% α -phase was also observed in the case of Dy-and Lu-doped alumina. This study revealed a new perspective on the significance of Ln-doping in alumina. Experimental Details Synthesis of Ln-doped alumina powders was achieved by starting with an in-situ nano-precipitation method to synthesize ammonium aluminum hydroxide carbonate (NH 4 Al 1−x RE x (OH) 2 CO 3 ) in an aqueous environment. The resulting powder was calcined at 1300 °C for 30 minutes in air. The detailed synthesis method is described in the Supporting Information section. The structural and chemical composition characterization was carried out by using an FEI Quanta 450FEG Scanning Electron Microscope. High resolution synchrotron powder diffraction data were collected using beamline 11-BM at the Advanced Photon Source (APS), Argonne National Laboratory. Discrete detectors covering an angular range from − 6 to 16° 2θ were scanned over a 34° 2θ range, with data points collected every 0.001° 2θ at a scan speed of 0.01°/s. All NMR data was recorded on a Bruker AVIII 400 MHz NMR Spectrometer with a 4 mm, two-channel MAS probe. Approximately 75 mg of material was packed into a 4 mm Zirconia rotor with Kel-F drive cap (Wilmad Lab Glass) and spun at the magic angle using a rate denoted in the text. The magic angle was confirmed using a KBr sample. 27 Al NMR pulses, offset, and chemical shift references were calibrated and check periodically during the data acquisition run using an alumina (powder) sample. For 1D 27 Al MAS spectra, the Bruker pulse program, excitation pulse, interscan delay, acquisition time, number of scans, sweep width, and experiment duration were "onepulse", 0.6 μ s at 100 W, 0.5 s, 16 ms, 20480, 600 ppm and 3 h, respectively. The data were processed by zero filling FID to 4096 points, Fourier Transform, phase correction, and referencing. For 2D 27 Al MQ-MAS spectra, the precise acquisition parameters were optimized for each individual sample. A representative example of the Bruker pulse program, excitation, conversion and selective pulses, interscan delay, acquisition time in F2 and F1, sweep width in F2 and F1, and experiment time were 7 μ s at 73 W, 2.5 μ s at 73 W, 30 μ s at 350 mW, 0.5 s, 24 ms, 10 ms, 400 ppm, the MAS spin rate (10 or 12 kHz, see figure caption) and three days, respectively. The data were processed by zero filling the matrix to 4096 × 512 complex points, 100 Hz line broadening in F2, Fourier Transform in both F2 and F1, phase correction, and shearing transform.
doi:10.1038/srep39946 pmid:28059121 pmcid:PMC5216414 fatcat:bry437qaibgonjz4kba7v23kny

1143 Predictors of Duct Dependent Congenital Heart Disease in Infants Transferred by Newborn Emergency Transport Service (NETS) Victoria

N. Gupta, C. Kamlin, M. Stewart, M. Cheung, N. Patel
2012 Archives of Disease in Childhood  
-2012-302724.1143 COF Kamlin, 2,4 M Stewart, 5 M Cheung, 4 N Patel. 1 Neonatal Unit, John Radcliffe Hospital, Oxford, UK; 2 Newborn Emergency Transport Services (NETS), Royal Children Hospital; 3 Department  ...  Fetal and CARDIAC INVOLVEMENT IN NEWBORN OF DIABETIC MOTHER: DIAGNOSIS AND FOLLOW UP OF EVOLUTION DISEASE IN INFANTS TRANSFERRED BY NEWBORN EMERGENCY TRANSPORT SERVICE (NETS) VICTORIA doi:10.1136/archdischild  ... 
doi:10.1136/archdischild-2012-302724.1143 fatcat:ep4yynyfhrdj5l7gd2j4gbmcby

Existence and uniqueness of global weak solutions to strain-limiting viscoelasticity with Dirichlet boundary data [article]

Miroslav Bulíček, Victoria Patel, Yasemin Şengül, Endre Süli
2020 arXiv   pre-print
We consider a system of evolutionary equations that is capable of describing certain viscoelastic effects in linearized yet nonlinear models of solid mechanics. The essence of the paper is that the constitutive relation, involving the Cauchy stress, the small strain tensor and the symmetric velocity gradient, is given in an implicit form. For a large class of implicit constitutive relations we establish the existence and uniqueness of a global-in-time large-data weak solution. We then focus on
more » ... he class of so-called limiting strain models, i.e., models for which the magnitude of the strain tensor is known to remain small a priori, regardless of the magnitude of the Cauchy stress tensor. For this class of models, a new technical difficulty arises, which is that the Cauchy stress is only an integrable function over its domain of definition, resulting in the underlying function spaces being nonreflexive and thus the weak compactness of bounded sequences of elements of these spaces is lost. Nevertheless, even for problems of this type we are able to provide a satisfactory existence theory, as long as the initial data have finite elastic energy and the boundary data fulfill natural compatibility conditions.
arXiv:2011.11683v1 fatcat:ifexsxnmp5fbhmq6szew6wrpie

Weak-strong Uniqueness for Heat Conducting non-Newtonian Incompressible Fluids [article]

Pablo Alexei Gazca-Orozco, Victoria Patel
2022 arXiv   pre-print
In this work, we introduce a notion of dissipative weak solution for a system describing the evolution of a heat-conducting incompressible non-Newtonian fluid. This concept of solution is based on the balance of entropy instead of the balance of energy and has the advantage that it admits a weak-strong uniqueness principle, justifying the proposed formulation. We provide a proof of existence of solutions based on finite element approximations, thus obtaining the first convergence result of a
more » ... erical scheme for the full evolutionary system including temperature dependent coefficients and viscous dissipation terms. Then we proceed to prove the weak-strong uniqueness property of the system by means of a relative energy inequality.
arXiv:2109.10636v2 fatcat:ctg6lfc5xjbj5bttcnsblvcpty
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