24,795 research outputs found

    Backwater controls of avulsion location on deltas

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    River delta complexes are built in part through repeated river-channel avulsions, which often occur about a persistent spatial node creating delta lobes that form a fan-like morphology. Predicting the location of avulsions is poorly understood, but it is essential for wetland restoration, hazard mitigation, reservoir characterization, and delta morphodynamics. Following previous work, we show that the upstream distance from the river mouth where avulsions occur is coincident with the backwater length, i.e., the upstream extent of river flow that is affected by hydrodynamic processes in the receiving basin. To explain this observation we formulate a fluvial morphodynamic model that is coupled to an offshore spreading river plume and subject it to a range of river discharges. Results show that avulsion is less likely in the downstream portion of the backwater zone because, during high-flow events, the water surface is drawn down near the river mouth to match that of the offshore plume, resulting in river-bed scour and a reduced likelihood of overbank flow. Furthermore, during low-discharge events, flow deceleration near the upstream extent of backwater causes enhanced deposition locally and a reduced channel-fill timescale there. Both mechanisms favor preferential avulsion in the upstream part of the backwater zone. These dynamics are fundamentally due to variable river discharges and a coupled offshore river plume, with implications for predicting delta response to climate and sea level change, and fluvio-deltaic stratigraphy

    Unusual presentation of an avulsion of the long digital extensor tendon in a dog: radiographic, computed tomographic, arthroscopic, surgical and histological findings

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    A long digital extensor tendon avulsion is reported in a 15-month-old intact male Great Dane with a right pelvic limb lameness of 2-week duration. The orthopedic, radiographic, computed tomographic, arthroscopic, surgical and histological findings are described. Surgical excision of the avulsed bone fragment and re-attachment of the tendon to the lateral joint capsule of the stifle joint was successful and the dog was free of lameness 6 and 12 months after therapy

    The anatomy of exhumed river-channel belts: Bedform to belt‐scale river kinematics of the Ruby Ranch Member, Cretaceous Cedar Mountain Formation, Utah, USA

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    Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barform strata. Dune and bar strata, channel planform geometry and bed topography are measured within exhumed fluvial strata exposed as ridges in the Ruby Ranch Member of the Cretaceous Cedar Mountain Formation, Utah, USA. The ridges are composed of lithified stacked channel belts, representing at least five or six re‐occupations of a single‐strand channel. Lateral sections reveal well‐preserved barforms constructed of subaqueous dune cross‐sets. The topography of palaeobarforms is preserved along the top surface of the outcrops. Comparisons of the channel‐belt centreline to local palaeotransport directions indicate that channel planform geometry was preserved through the re‐occupations, rather than being obscured by lateral migration. Rapid avulsions preserved the state of the active channel bed and its individual bars at the time of abandonment. Inferred minimum sedimentation durations for the preserved elements, inferred from cross‐set thickness distributions and assumed bedform migration rates, vary within a belt from one to ten days. Using only these local sedimentological measurements, the depositional setting is interpreted as a fluvial megafan, given the similarity in river kinematics. This paper provides a systematic methodology for the future synthesis of vertical and planview data, including the drone‐equipped 2020 Mars Rover mission, to exhumed fluvial and deltaic strata

    L-configuration re-attachment of distal biceps tendon rupture

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    In distal biceps tendon ruptures, re-attachment to the radial tuberosity should ensure adequate tendon to bone contact for optimal healing

    Littoral Rights Under the Takings Doctrine: The Clash Between the Ius Naturale And Stop The Beach Renourishment

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    Background. Organizing and performing patient transfers in the continuum of care is part of the work of nurses and other staff of a multiprofessional healthcare team. An understanding of discharge practices is needed in order to ultimate patients’ transfers from high technological intensive care units (ICU) to general wards. Aim. To describe, as experienced by intensive care and general ward staff, what strategies could be used when organizing patient’s care before, during, and after transfer from intensive care. Method. Interviews of 15 participants were conducted, audio-taped, transcribed verbatim, and analyzed using qualitative content analysis. Results. The results showed that the categories secure, encourage, and collaborate are strategies used in the three phases of the ICU transitional care process. The main category; a safe, interactive rehabilitation process, illustrated how all strategies were characterized by an intention to create and maintain safety during the process. A three-way interaction was described: between staff and patient/families, between team members and involved units, and between patient/family and environment. Discussion/Conclusions. The findings highlight that ICU transitional care implies critical care rehabilitation. Discharge procedures need to be safe and structured and involve collaboration, encouraging support, optimal timing, early mobilization, and a multidiscipline approach

    Blunt traumatic celiac artery avulsion managed with celiac artery ligation and open aorto-celiac bypass.

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    Traumatic celiac artery injuries are rare and highly lethal with reported mortality rates of 38-62%. The vast majority are caused by penetrating trauma with only 11 reported cases due to blunt trauma (Graham et al., 1978; Asensio et al., 2000, 2002). Only 3 of these cases were complete celiac artery avulsions. Management options described depend upon the type of injury and have included medical therapy with anti-platelet agents or anti-coagulants, endovascular stenting, and open ligation. We report a case of a survivor of complete celiac artery avulsion from blunt trauma managed by open bypass

    Isolated olecranon fractures in children affected by osteogenesis imperfecta type I treated with single screw or tension band wiring system: outcomes and pitfalls in relation to bone mineral density

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    The purpose of this study is to compare the results of 2 techniques, tension band wiring (TBW) and fixation with screws, in olecranon fractures in children affected with osteogenesis imperfecta (OI) type I. Between 2010 and 2014, 21 olecranon fractures in 18 children with OI (average age: 12 years old) were treated surgically. Ten patients were treated with the screw fixation and 11 with TBW. A total of 65% of olecranon fractures occurred as a result of a spontaneous avulsion of the olecranon during the contraction of the triceps muscle. The average follow-up was 36 months. Among the children treated with 1 screw, 5 patients needed a surgical revision with TBW due to a mobilization of the screw. In this group, the satisfactory results were 50%. In patients treated with TBW, the satisfactory results were 100% of the cases. The average Z-score, the last one recorded in the patients before the trauma, was -2.53 in patients treated with screw fixation and -2.04 in those treated with TBW. TBW represents the safest surgical treatment for patients suffering from OI type I, as it helps to prevent the rigidity of the elbow through an earlier recovery of the range of motion, and there was no loosening of the implant. In analyzing the average Z-score before any fracture, the fixation with screws has an increased risk of failure in combination with low bone mineral density

    The homuncular jigsaw: investigations of phantom limb and body awareness following brachial plexus block or avulsion

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    Many neuropsychological theories agree that the brain maintains a relatively persistent representation of one's own body, as indicated by vivid "phantom" experiences. It remains unclear how the loss of sensory and motor information contributes to the presence of this representation. Here, we focus on new empirical and theoretical evidence of phantom sensations following damage to or an anesthetic block of the brachial plexus. We suggest a crucial role of this structure in understanding the interaction between peripheral and central mechanisms in health and in pathology. Studies of brachial plexus function have shed new light on how neuroplasticity enables "somatotopic interferences", including pain and body awareness. Understanding the relations among clinical disorders, their neural substrate, and behavioral outcomes may enhance methods of sensory rehabilitation for phantom limbs
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