Debris Flow Fans in Yosemite Valley National Park, California

Formation of debris flow fans poses a potential hazard to the infrastructure and inhabitants of Yosemite Valley. Research was conducted on debris flow fans at three field sites in Yosemite Valley: Indian Creek, Eagle Creek, and Sentinel Creek. The study utilized a Trimble Pro XR Differential Global Positioning System (DGPS), Cosmogenic Berellium-10 (10Be) dating, and debris flow volume measurements to better understand the spatial distribution, age, and magnitude of prehistoric debris flow deposits at each field site. It is hypothesized that all three fans were constructed quickly after the last glacial maximum (LGM), which is dated at 19.8 ka. It is also proposed that increased rainfall and sediment production during the LGM provided the necessary conditions for debris flow initiation in each catchment. Future debris flow initiation is contingent on channels being pre-loaded with sediment and above average rainfall. At the present time, the channels are loaded with debris, but future debris flow initiation seems unlikely to occur because the fans have been inactive for thousands of years. Debris flows only pose a significant hazard to Yosemite Valley, if and when, the optimum conditions are met

Search for supersymmetry with a compressed mass spectrum in the vector boson fusion topology with 1-lepton and 0-lepton final states in proton-proton collisions at s=\sqrt{s}= 13 TeV

A search for supersymmetric particles produced in the vector boson fusion topology in proton-proton collisions is presented. The search targets final states with one or zero leptons, large missing transverse momentum, and two jets with a large separation in rapidity. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV collected in 2016 with the CMS detector at the LHC. The observed dijet invariant mass and lepton-neutrino transverse mass spectra are found to be consistent with the standard model predictions. Upper limits are set on the cross sections for chargino ($\widetilde\chi_1^\pm$) and neutralino ($\widetilde\chi_2^0$) production with two associated jets. For a compressed mass spectrum scenario in which the $\widetilde\chi_1^\pm$ and $\widetilde\chi_2^0$ decays proceed via a light slepton and the mass difference between the lightest neutralino $\widetilde\chi_1^0$ and the mass-degenerate particles $\widetilde\chi_1^\pm$ and $\widetilde\chi_2^0$ is 1 (30) GeV, the most stringent lower limit to date of 112 (215) GeV is set on the mass of these latter two particles