The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.2

Possible molecular conformations in peptide nanorings and nanotubes were theoretically investigated by a mathematical conformation analysis as well as ab initio Hartree−Fock calculations. The mathematical analysis predicts not only the conventional nanorings having an extended-type (E-type) backbone (trans zigzag) but also the novel ones having bound-type (B-type) backbones with a smaller internal diameter. Ab initio calculations for the amino acid substitution reveal that all 20 encoded residues can form both types of the above nanorings as a local minimum. However, the energetically stable type is determined in accordance with the kind of the replaced side chains. Moreover, the present work theoretically reveals that both types of nanorings stack to form nanotubes through inter-ring hydrogen bonds, i.e., larger E-type nanotubes and smaller B-type nanotubes. Electronically, the HOMO and LUMO states of the nanoring and nanotube backbones are formed by the in-plane π state. The replacement by the appropriate residues is furthermore predicted to intrude additional levels in the energy gap and to form the frontier states localized at the side chains.

An approach of membership revocation in group signatures is verifier-local revocation (VLR for short). In this approach, only verifiers are involved in the revocation mechanism, while signers have no involvement. Thus, since signers have no load, this approach is suitable for mobile environments. Although Boneh and Shacham recently proposed a VLR group signature scheme from bilinear maps, this scheme does not satisfy the backward unlikability. The backward unlikability means that even after a member is revoked, signatures produced by the member before the revocation remain anonymous. In this paper, we propose VLR group signature schemes with the backward unlinkability from bilinear maps. 2 Model and Security Definitions We show a model of VLR group signature scheme with backward unlinkability, which is extended from a model of VLR group signature scheme proposed in [7]. Definition 1. A VLR group signature scheme with backward unlinkability consists of the following algorithms: KeyGen(n, T): It is a probabilistic algorithm on inputs n, which is the number of members, and T , which is the number of time intervals. It outputs a Then, the security requirements, Correctness, Traceability, and BU-anonymity, are defined as follows, which are also extended from [7]. Definition 2 (Correctness). Correctness requires that for all (gpk, gsk, grt) = KeyGen(n, T), all j ∈ [1, T ], all RL j , all i ∈ [1, n], and all M ∈ {0, 1} * , Verify(gpk, j, RL j , Sign(gpk, j, gsk[i], M), M) = valid ⇐⇒ grt[i][j] / ∈ RL j .

An approach of membership revocation in group signatures is verifier-local revocation (VLR for short). In this approach, only verifiers are involved in the revocation mechanism, while signers have no involvement. Thus, since signers have no load, this approach is suitable for mobile environments. Although Boneh and Shacham recently proposed a VLR group signature scheme from bilinear maps, this scheme does not satisfy the backward unlikability. The backward unlikability means that even after a member is revoked, signatures produced by the member before the revocation remain anonymous. In this paper, we propose VLR group signature schemes with the backward unlinkability from bilinear maps. 2 Model and Security Definitions We show a model of VLR group signature scheme with backward unlinkability, which is extended from a model of VLR group signature scheme proposed in [7]. Definition 1. A VLR group signature scheme with backward unlinkability consists of the following algorithms: KeyGen(n, T): It is a probabilistic algorithm on inputs n, which is the number of members, and T , which is the number of time intervals. It outputs a group public key gpk, an n-element vector of members' secret keys gsk =

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GaAs-GaAsP and InGaAs-AlGaAs strained-layer superlattice photocathodes are presented as emission sources for highly polarized electron beams. The GaAs-GaAsP cathode achieved a maximum polarization of 92(±6)% with a quantum efficiency of 0.5%, while the InGaAs-AlGaAs cathode provides a higher quantum efficiency (0.7%) but a lower polarization (77(±5)%). Criteria for achieving high polarization using superlattice (SL) photocathodes are discussed based on experimental spin-resolved quantum efficiency spectra.