Sustaining supercooled mixed phase via resonant oscillations of the order parameter

We investigate the dynamics of a first order transition when the order parameter field undergoes resonant oscillations, driven by a periodically varying parameter of the free energy. This parameter could be a background oscillating field as in models of pre-heating after inflation. In the context of condensed matter systems, it could be temperature $T$, or pressure, external electric/magnetic field etc. We show that with suitable driving frequency and amplitude, the system remains in a type of mixed phase, without ever completing transition to the stable phase, even when the oscillating parameter of the free energy remains below the corresponding critical value (for example, with oscillating temperature, $T$ always remains below the critical temperature $T_c$). This phenomenon may have important implications. In cosmology, it will imply prolonged mixed phase in a first order transition due to coupling with background oscillating fields. In condensed matter systems, it will imply that using oscillating temperature (or, more appropriately, pressure waves) one may be able to sustain liquids in a mixed phase indefinitely at low temperatures, without making transition to the frozen phase.Comment: 17 pages, 7 figures, Expanded version with more detail

Excited hadrons as a signal for quark-gluon plasma formation

At the quark-hadron transition, when quarks get confined to hadrons, certain orbitally excited states, namely those which have excitation energies above the respective $L = 0$ states of the same order as the transition temperature $T_c$, may form easily because of thermal velocities of quarks at the transition temperature. We propose that the ratio of multiplicities of such excited states to the respective $L = 0$ states can serve as an almost model independent signal for the quark-gluon plasma formation in relativistic heavy-ion collisions. For example, the ratio $R^*$ of multiplicities of $D_{SJ}^{*\pm}(2317)(J^P = 0^+)$ and $D_S^{*\pm}(2112)(J^P = 1^-)$ when plotted with respect to the center of mass energy of the collision $\sqrt{s}$ (or vs. centrality/number of participants), should show a jump at the value of $\sqrt{s}$ beyond which the QGP formation occurs. This should happen irrespective of the shape of the overall plot of $R^*$ vs. $\sqrt{s}$. Recent data from RHIC on $\Lambda^*/\Lambda$ vs. N$_{part}$ for large values of N$_{part}$ may be indicative of such a behavior, though there are large error bars. We give a list of several other such candidate hadronic states.Comment: 19 pages, RevTex, no figures, minor change

A dual-mass resonant mems gyroscope design with electrostatic tuning for frequency mismatch compensation

The micro-electro-mechanical systems (MEMS)-based sensor technologies are considered to be the enabling factor for the future development of smart sensing applications, mainly due to their small size, low power consumption and relatively low cost. This paper presents a new structurally and thermally stable design of a resonant mode-matched electrostatic z-axis MEMS gyroscope considering the foundry constraints of relatively low cost and commercially available silicon-on-insulator multi-user MEMS processes (SOIMUMPs) microfabrication process. The novelty of the proposed MEMS gyroscope design lies in the implementation of two separate masses for the drive and sense axis using a unique mechanical spring configuration that allows minimizing the cross-axis coupling between the drive and sense modes. For frequency mismatch compensation between the drive and sense modes due to foundry process uncertainties and gyroscope operating temperature variations, a comb-drive-based electrostatic tuning is implemented in the proposed design. The performance of the MEMS gyroscope design is verified through a detailed coupled-field electric-structural-thermal finite element method (FEM)-based analysis

Pelatihan Mendesain Percepatan Penyusunan Skripsi

Penyusunan Skripsi atau tugas akhir mahasiswa merupakan fase bagi seorang mahasiswa dalam penyelesaian proses Pendidikan di jenjang S1. Fase ini cukup krusial, karena bisa jadi terdapat beberapa mahasiswa berusaha fokus dan ingin cepat mengakhiri masa studi di perguruan tinggi, namun tidak sedikit juga terdapat mahasiswa yang terlena atau lengah dengan berbagai aktivitas pribadi lainnya, sehingga penyusunan Skripsi jadi terbengkalai dan tak terurus yang berakibat pada lambatnya penyelesaian Skripsi oleh yang bersangkutan. Pelatihan percepatan penyusunan Skripsi diyakini mampu membantu para mahasiswa dalam upaya mempercepat penyusunan Skripsi mereka dan tentunya juag mempercepat penyelesaian studi mereka pada jenjang S1. Pada kegiatan ini dijelaskan dan praktekkan bagaimana cara melakukan perancangan terhadap kegiatan penyusunan Skripsi, dan bagaimana cara melaksanakan rancangan yang telah dibuat

Bentonite Reinforced Chitosan Scaffold: Effect of Bentonite Exfoliation on Scaffold Properties

Chitosan is under investigation as biodegradable scaffolding material for tissue engineering. Crosslinked chitosan alone cannot form a self-supporting scaffold hence it needs reinforcement. The group reported fabrication of chitosan scaffolds reinforced by exfoliated and non-exfoliated bentonite and compared their properties. Scaffolds were fabricated by freeze-drying technique. Bentonite was exfoliated by allowing it to swell in water for a certain time interval. XRD profile showed that swelling reduced the crystallinity of bentonite. Both types of bentonite dispersed well in the chitosan matrix and imparted structural stability to the scaffolds. Scaffolds had interconnected pores, apparent porosity of scaffold with exfoliated bentonite was higher than of scaffold with unexfoliated bentonite. The scaffolds swelled almost 35% in 3 days without losing the structural integrity. The scaffolds could be compressed to 50% of their original height. Compression modulus of scaffold with exfoliated bentonite was higher than that of unexfoliated bentonite scaffold