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Open Access Publications from the University of California

Scholarly Works (6 results)

  • Article
  • Peer Reviewed
Research Reports (2008)

Carsharing (or short-term auto use) organizations provide members access to a fleet of shared vehicles on an hourly basis, reducing the need for private vehicle ownership. This paper reflects a ten-year retrospective of carsharing in Canada and the United States (U.S.), including results from a 2008 operator survey. Since 1994, a total of 50 carsharing programs have been deployed in North AmericaØ33 are operational, and 17 are defunct. As of July 1, 2008, there are 14 active programs in Canada and 19 in the U.S., with approximately 319,000 carsharing members sharing over 7,500 vehicles in North America. Another six programs are planned to launch in North America by January 2009. The four largest providers in the U.S. and Canada support 99% and 95.2% of total membership, respectively.

In this ten-year retrospective, the authors examine North America's carsharing evolution from initial market entry and experimentation (1994 to mid-2002) to growth and market diversification (mid-2002 to late-2007) to commercial mainstreaming (late-2007 to present). This evolution includes increased competition, new market entrants, program consolidation, increased market diversification, capital investment, technological advancement, and greater inter-operator collaboration. Ongoing growth and competition are forecasted. Rising fuel costs and increased climate change awareness will likely facilitate this expansion.

    Cover page: North American Carsharing: A Ten-Year Retrospective
    • Article
    • Peer Reviewed
    UC Berkeley Previously Published Works (2009)

    Carsharing organizations (or short-term auto use) provide members access to a fleet of shared vehicles on an hourly basis, reducing the need for private vehicle ownership. This paper reflects a ten-year retrospective of carsharing in Canada and the United States (U.S.), including results from a 2008 operator survey. Since 1994, a total of 50 carsharing programs have been deployed in North America⎯33 are operational, and 17 are defunct. As of July 1, 2008, there were 14 active programs in Canada and 19 in the U.S., with approximately 319,000 carsharing members sharing over 7,500 vehicles in North America. Another six programs were planned to launch in North America by January 2009. The four largest providers in the U.S. and Canada support 99% and 95.2% of total membership, respectively.

    In this ten-year retrospective, the authors examine North America’s carsharing evolution from initial market entry and experimentation (1994 to mid-2002) to growth and market diversification (mid-2002 to late-2007) to commercial mainstreaming (late-2007 to present). This evolution includes increased competition, new market entrants, program consolidation, increased market diversification, capital investment, technological advancement, and greater inter-operator collaboration. Ongoing growth and competition are forecasted. Rising fuel costs and increased climate change awareness will likely facilitate this expansion.

      Cover page: North American Carsharing: A Ten-Year Retrospective
      • Article
      • Peer Reviewed
      Recent Work (2009)

      Carsharing organizations (or short-term auto use) provide members access to a fleet of shared vehicles on an hourly basis, reducing the need for private vehicle ownership. This paper reflects a ten-year retrospective of carsharing in Canada and the United States (U.S.), including resultsfrom a 2008 operator survey. Since 1994, a total of 50 carsharing programs have been deployed in North America33 are operational, and 17 are defunct. As of July 1, 2008, there were 14 active programs in Canada and 19 in the U.S., with approximately 319,000 carsharing memberssharing over 7,500 vehicles in North America. Another six programs were planned to launch in North America by January 2009. The four largest providers in the U.S. and Canada support 99%and 95.2% of total membership, respectively.

      In this ten-year retrospective, the authors examine North America’s carsharing evolution from initial market entry and experimentation (1994 to mid-2002) to growth and market diversification (mid-2002 to late-2007) to commercial mainstreaming (late-2007 to present). This evolution includes increased competition, new market entrants, program consolidation, increased market diversification, capital investment, technological advancement, and greater inter-operator collaboration. Ongoing growth and competition are forecasted. Rising fuel costs and increased climate change awareness will likely facilitate this expansion.

        Cover page: North American Carsharing: A Ten Year Retrospective
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2020)

        Objective

        To compare risk factors, clinical presentation, and outcomes after posterior circulation arterial ischemic stroke (PCAIS) and anterior circulation arterial ischemic stroke (ACAIS) in neonates and children.

        Methods

        In this international multicenter observational study including neonates and children up to 18 years of age with arterial ischemic stroke (AIS), we compared clinical and radiologic features according to stroke location.

        Results

        Of 2,768 AIS cases, 507 (18%) were located in the posterior circulation, 1,931 (70%) in the anterior circulation, and 330 (12%) involved both. PCAIS was less frequent in neonates compared to children (8.8% vs 22%, p < 0.001). Children with PCAIS were older than children with ACAIS (median age 7.8 [interquartile range (IQR) 3.1-14] vs 5.1 [IQR 1.5-12] years, p < 0.001), and more often presented with headache (54% vs 32%, p < 0.001) and a lower Pediatric NIH Stroke Scale score (4 [IQR 2-8] vs 8 [IQR 3-13], p = 0.001). Cervicocephalic artery dissections (CCAD) were more frequent (20% vs 8.5%, p < 0.001), while cardioembolic strokes were less frequent (19% vs 32%, p < 0.001) in PCAIS. Case fatality rates were equal in both groups (2.9%). PCAIS survivors had a better outcome (normal neurologic examination at hospital discharge in 29% vs 21%, p = 0.002) than ACAIS survivors, although this trend was only observed in children and not in neonates.

        Conclusion

        PCAIS is less common than ACAIS in both neonates and children. Children with PCAIS are older and have a higher rate of CCAD, lower clinical stroke severity, and better outcome than children with ACAIS.
          Cover page: Comparative study of posterior and anterior circulation stroke in childhood: Results from the International Pediatric Stroke Study.
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2017)

          Background

          The reproducibility of transcranial Doppler (TCD) ultrasound measurements in Sturge-Weber syndrome (SWS) and TCD's ability to predict neurological progression is unknown.

          Methods

          In 14 individuals with SWS, TCD measured mean flow velocity, pulsatility index, peak systolic velocity, and end-diastolic velocity in the middle, posterior, and anterior cerebral arteries of the affected and unaffected hemisphere. TCD was performed either once (n = 5) or twice in one day (n = 9). We assessed the reproducibility of the measurements performed twice on the same day on subjects and compared the TCD measurements to previously published age-matched controls. Clinically obtained neuroimaging was scored for extent and severity of SWS brain involvement. Patients were prospectively assigned SWS neuroscores.

          Results

          Middle cerebral artery velocity (r = 0.79, P = 0.04, n = 7), posterior cerebral artery velocity (r = 0.90, P = 0.04, n = 5), and anterior cerebral artery pulsatility index (r = 0.82, P = 0.02, n = 7) were reproducible TCD measurements comparing same-day percent side-to-side differences. In subjects with SWS, affected and unaffected mean peak systolic velocity and end-diastolic velocity in the middle, posterior, and anterior cerebral arteries were globally lower compared with age-matched control subjects. Subjects with the lowest affected middle cerebral artery velocity had the greatest worsening in the total neurological score between time 1 and 2 (r = -0.73, P = 0.04, n = 8) and the most severe magnetic resonance imaging involvement of the affected frontal lobe (r = -0.82, P = 0.007, n = 9).

          Conclusions

          TCD may be a reliable measure with potential clinical value, indicating that blood flow may be globally decreased in SWS patients with unilateral brain involvement.
            Cover page: Reliability and Clinical Correlation of Transcranial Doppler Ultrasound in Sturge-Weber Syndrome
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2024)
            BACKGROUND: Surgical revascularization decreases the long-term risk of stroke in children with moyamoya arteriopathy but can be associated with an increased risk of stroke during the perioperative period. Evidence-based approaches to optimize perioperative management are limited and practice varies widely. Using a modified Delphi process, we sought to establish expert consensus on key components of the perioperative care of children with moyamoya undergoing indirect revascularization surgery and identify areas of equipoise to define future research priorities. METHODS: Thirty neurologists, neurosurgeons, and intensivists practicing in North America with expertise in the management of pediatric moyamoya were invited to participate in a three-round, modified Delphi process consisting of a 138-item practice patterns survey, anonymous electronic evaluation of 88 consensus statements on a 5-point Likert scale, and a virtual group meeting during which statements were discussed, revised, and reassessed. Consensus was defined as ≥ 80% agreement or disagreement. RESULTS: Thirty-nine statements regarding perioperative pediatric moyamoya care for indirect revascularization surgery reached consensus. Salient areas of consensus included the following: (1) children at a high risk for stroke and those with sickle cell disease should be preadmitted prior to indirect revascularization; (2) intravenous isotonic fluids should be administered in all patients for at least 4 h before and 24 h after surgery; (3) aspirin should not be discontinued in the immediate preoperative and postoperative periods; (4) arterial lines for blood pressure monitoring should be continued for at least 24 h after surgery and until active interventions to achieve blood pressure goals are not needed; (5) postoperative care should include hourly vital signs for at least 24 h, hourly neurologic assessments for at least 12 h, adequate pain control, maintaining normoxia and normothermia, and avoiding hypotension; and (6) intravenous fluid bolus administration should be considered the first-line intervention for new focal neurologic deficits following indirect revascularization surgery. CONCLUSIONS: In the absence of data supporting specific care practices before and after indirect revascularization surgery in children with moyamoya, this Delphi process defined areas of consensus among neurosurgeons, neurologists, and intensivists with moyamoya expertise. Research priorities identified include determining the role of continuous electroencephalography in postoperative moyamoya care, optimal perioperative blood pressure and hemoglobin targets, and the role of supplemental oxygen for treatment of suspected postoperative ischemia.
              Cover page: Pediatric Moyamoya Revascularization Perioperative Care: A Modified Delphi Study.
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