Characterizing neutral modes of fractional states in the second Landau level.

Fractionally charged quasiparticles, which obey non-abelian statistics, were predicted to exist in the ν=8/3, ν=5/2, and ν=7/3 fractional quantum Hall states (in the second Landau level). Here we present measurements of charge and neutral modes in these states. For both ν=7/3 and ν=8/3 states, we found a quasiparticle charge e=1/3 and an upstream neutral mode only in ν=8/3-excluding the possibility of non-abelian Read-Rezayi states and supporting Laughlin-like states. The absence of an upstream neutral mode in the ν=7/3 state also proves that edge reconstruction was not present in the ν=7/3 state, suggesting its absence also in ν=5/2 state, and thus may provide further support for the non-abelian anti-pfaffian nature of the ν=5/2 state.

Once daily ceftriaxone for meningococcemia and meningococcal meningitis.

Twenty children with meningococcal disease (15 with meningococcal meningitis and 5 with meningococcemia without meningitis) were treated with ceftriaxone, 80 to 100 mg/kg/day for 4 days. An additional 22 patients with meningococcal disease (13 with meningitis, 9 with meningococcemia without meningitis) were treated with penicillin G. On the basis of the Damrosch-Stiehm scoring system, 19 patients were classified in the poor prognostic group and were treated with antishock therapy. Clinical recovery time and normalization of CSF were compared in two groups. When the complications were compared, necrotic skin lesions were more frequently seen in the penicillin G group than in those who received ceftriaxone. Ceftriaxone is an effective and safe drug and offers the advantage of once daily administration for treatment of meningococcal disease in pediatric patients.

Extracting net current from an upstream neutral mode in the fractional quantum Hall regime.

Upstream neutral modes, counter propagating to charge modes and carrying energy without net charge, had been predicted to exist in some of the fractional quantum Hall states and were recently observed via noise measurements. Understanding such modes will assist in identifying the wavefunction of these states, as well as shedding light on the role of Coulomb interactions within edge modes. Here, operating mainly in the ν=2/3 state, we place a quantum dot a few micrometres upstream of an ohmic contact, which serves as a 'neutral modes source'. We show that the neutral modes heat the input of the dot, causing a net thermo-electric current to flow through it. Heating of the electrons leads to a decay of the neutral mode, manifested in the vanishing of the thermo-electric current at T>110 mK. This set-up provides a straightforward method to investigate upstream neutral modes without turning to the more cumbersome noise measurements.