Surface heterogeneity impacts on boundary layer dynamics via energy balance partitioning

The role of land-atmosphere interactions under heterogeneous surface conditions is investigated in order to identify mechanisms responsible for altering surface heat and moisture fluxes. Twelve coupled land surface – large eddy simulation scenarios with four different length scales of surface variability under three different horizontal wind speeds are used in the analysis. The base case uses Landsat ETM imagery over the Cloud Land Surface Interaction Campaign (CLASIC) field site for 3 June 2007. Using wavelets, the surface fields are band-pass filtered in order to maintain the spatial mean and variances to length scales of 200 m, 1600 m, and 12.8 km as lower boundary conditions to the model (approximately 0.25, 1.2 and 9.5 times boundary layer height). The simulations exhibit little variation in net radiation. Rather, there is a pronounced change in the partitioning of the surface energy between sensible and latent heat flux. The sensible heat flux is dominant for intermediate surface length scales. For smaller and larger scales of surface heterogeneity, which can be viewed as being more homogeneous, the latent heat flux becomes increasingly important. The simulations showed approximately 50 Wm<sup>−2</sup> difference in the spatially averaged latent heat flux. The results reflect a general decrease of the Bowen ratio as the surface conditions transition from heterogeneous to homogeneous. Air temperature is less sensitive to variations in surface heterogeneity than water vapor, which implies that the role of surface heterogeneity may be to maximize convective heat fluxes through modifying and maintaining local temperature gradients. More homogeneous surface conditions (i.e. smaller length scales), on the other hand, tend to maximize latent heat flux. The intermediate scale (1600 m) this does not hold, and is a more complicated interaction of scales. Scalar vertical profiles respond predictably to the partitioning of surface energy. Fourier spectra of the vertical wind speed, air temperature and specific humidity (<i>w</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i>, <i>T</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i> and <i>q</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i>) and associated cospectra (<i>w</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i><i>T</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i>, <i>w</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i><i>q</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i> and <i>T</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i><i>q</i><span style="position: relative; top: -.5em; left: -.65em;">~</span><i style=" margin-left:-.7em"></i>), however, are insensitive to the length scale of surface heterogeneity, but the near surface spectra are sensitive to the mean wind speed

Accuracy of Emergency Medical Services Dispatcher and Crew Diagnosis of Stroke in Clinical Practice.

BACKGROUND: Accurate recognition of stroke symptoms by Emergency Medical Services (EMS) is necessary for timely care of acute stroke patients. We assessed the accuracy of stroke diagnosis by EMS in clinical practice in a major US city. METHODS AND RESULTS: Philadelphia Fire Department data were merged with data from a single comprehensive stroke center to identify patients diagnosed with stroke or TIA from 9/2009 to 10/2012. Sensitivity and positive predictive value (PPV) were calculated. Multivariable logistic regression identified variables associated with correct EMS diagnosis. There were 709 total cases, with 400 having a discharge diagnosis of stroke or TIA. EMS crew sensitivity was 57.5% and PPV was 69.1%. EMS crew identified 80.2% of strokes with National Institutes of Health Stroke Scale (NIHSS) ≥5 and symptom durationmodel, correct EMS crew diagnosis was positively associated with NIHSS (NIHSS 5-9, OR 2.62, 95% CI 1.41-4.89; NIHSS ≥10, OR 4.56, 95% CI 2.29-9.09) and weakness (OR 2.28, 95% CI 1.35-3.85), and negatively associated with symptom duration \u3e270 min (OR 0.41, 95% CI 0.25-0.68). EMS dispatchers identified 90 stroke cases that the EMS crew missed. EMS dispatcher or crew identified stroke with sensitivity of 80% and PPV of 50.9%, and EMS dispatcher or crew identified 90.5% of patients with NIHSS ≥5 and symptom duration \u3c6 \u3eh. CONCLUSION: Prehospital diagnosis of stroke has limited sensitivity, resulting in a high proportion of missed stroke cases. Dispatchers identified many strokes that EMS crews did not. Incorporating EMS dispatcher impression into regional protocols may maximize the effectiveness of hospital destination selection and pre-notification

Recent Legal Literature

Daniel: A treatise on the Law of Negotiable Instruments; Voorheis: A Treatise on the Law of the Measure of Damages for Personal Injurie

Recent Legal Literature

Daniel: A treatise on the Law of Negotiable Instruments; Voorheis: A Treatise on the Law of the Measure of Damages for Personal Injurie

William Wilberforce: Integration of Faith and Politics

A research paper that covers the historical context, main issues, and significance of William Wilberforce and his social reforms