Expansion microscopy is a recently introduced technique in which fluorophores on fixed specimens are linked to a swellable polymer that is physically expanded to enable super-resolution microscopy with ordinary microscopes. We have developed and characterized new methods for linking fluorophores to the polymer that now enable expansion microscopy with conventional fluorescently-labeled antibodies and fluorescent proteins. Our methods simplify the procedure, expand the palette of compatible labels, and will aid in rapid dissemination of the technique.

A search for heavy Majorana neutrinos in events containing a pair of high-p T leptons of the same charge and high-p T jets is presented. The search uses 20.3 fb −1 of pp collision data collected with the ATLAS detector at the CERN Large Hadron Collider with a centre-of-mass energy of √ s = 8 TeV. The data are found to be consistent with the background-only hypothesis based on the Standard Model expectation. In the context of a Type-I seesaw mechanism, limits are set on the production cross-section times branching ratio for production of heavy Majorana neutrinos in the mass range between 100 and 500 GeV. The limits are subsequently interpreted as limits on the mixing between the heavy Majorana neutrinos and the Standard Model neutrinos. In the context of a left-right symmetric model, limits on the production cross-section times branching ratio are set with respect to the masses of heavy Majorana neutrinos and heavy gauge bosons W R and Z . Conclusions 20The ATLAS collaboration 28 IntroductionThe discovery of mixing between generations of neutrinos [1] has established that at least two of the neutrinos have small non-zero masses. A unique feature of neutrinos compared to other fermions in the Standard Model (SM) is that neutrinos could be their own antiparticles, so-called Majorana fermions. If this is realised in nature, then the unusually low mass scale of the light neutrinos could be generated by a seesaw mechanism [2][3][4][5][6][7] which -1 -JHEP07(2015)162 Figure 1. The tree-level diagram for the production of a heavy Majorana neutrino (N ) in the mTISM model. Lepton flavour is denoted by α and β. Lepton flavour is assumed to be conserved, such that α = β. The W boson produced from the N decay is on-shell and, in this case, decays hadronically.would imply the existence of yet unobserved heavy Majorana neutrino states. The nature of Majorana neutrinos would explicitly allow for lepton number violation.In this paper, a search is presented for heavy Majorana neutrinos using the ATLAS detector at the Large Hadron Collider (LHC). The data sample was collected in 2012 during √ s = 8 TeV pp collisions and corresponds to an integrated luminosity of 20.3 fb −1 . Heavy Majorana neutrinos with masses above 50 GeV are considered. In this regime, the production and subsequent decay of heavy Majorana neutrinos could lead to a final state containing exactly two charged leptons, where the leptons may have the same or opposite charge in equal fractions of the heavy neutrino decays. Only lepton pairs of the same charge (same-sign) are considered as there is a smaller expected SM background for pairs of same-sign leptons than for pairs of leptons of opposite charge (opposite-sign). The search includes the ee and µµ final states.The search is guided by two theoretical models. In the first model, the SM is extended in the simplest way to include right-handed neutrinos [8], such that light neutrino masses are generated by a Type-I seesaw mechanism or by radiative corrections [9]. In this minimal Type-I seesaw mechanism...

The prevailing amyloid hypothesis for Alzheimer's disease (AD) holds that amyloid beta-protein (Abeta) causes neuronal degeneration by forming neurotoxic fibrillar structures. Yet, many aspects of AD pathology and symptoms are not well explained by this hypothesis. Here, we present evidence that neurotoxicity of soluble oligomeric Abeta closely corresponds to the selective neurodegeneration so distinctly manifest in AD. Selectivity was first observed in vitro, where only the human central nervous system neuronal cells were susceptible to soluble oligomeric Abeta. Furthermore, in mouse cerebral slice treated with soluble oligomeric Abeta, selective regiospecific toxicity was evident in the hippocampal CA1, a division important for memory, but not in the CA3 subfield. The fibrillar Abeta, however, killed neurons in all regions of the cerebral slice cultures and also in cerebellar slices. Remarkably, even at the highest soluble oligomeric Abeta concentrations, cerebellar neurons were completely spared, consistent with one of the hallmark features of AD pathology. Our observation of the selective neurodegeneration of soluble oligomeric Abeta to neurons involved in cognitive function may provide a new opportunity for the development of an effective AD therapy as well as elucidating the pathological mechanism of AD.

The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to dielectron or dimuon final states. Results are presented from an analysis of proton-proton (pp) collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb −1 in the dimuon channel. A narrow resonance with Standard Model Z couplings to fermions is excluded at 95% confidence level for masses less than 2.79 TeV in the dielectron channel, 2.53 TeV in the dimuon channel, and 2.90 TeV in the two channels combined. Limits on other model interpretations are also presented, including a grand-unification model based on the E 6 gauge group, Z Ã bosons, minimal Z 0 models, a spin-2 graviton excitation from Randall-Sundrum models, quantum black holes, and a minimal walking technicolor model with a composite Higgs boson.

A search for pair production of vector-like quarks, both up-type (T ) and downtype (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at √ s = 8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb −1 . Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT → W b+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT → Ht+X and BB → Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → W b, Zt, Ht and B → W t, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.