5,141 research outputs found
The rational classification of links of codimension >2
Fix an integer m and a multi-index p = (p_1, ..., p_r) of integers p_i < m-2.
The set of links of codimension > 2, with multi-index p, E(p, m), is the set of
smooth isotopy classes of smooth embeddings of the disjoint union of the
p_i-spheres into the m-sphere. Haefliger showed that E(p, m) is a finitely
generated abelian group with respect to embedded connected summation and
computed its rank in the case of knots, i.e. r=1. For r > 1 and for
restrictions on p the rank of this group can be computed using results of
Haefliger or Nezhinsky. Our main result determines the rank of the group E(p,
m) in general. In particular we determine precisely when E(p,m) is finite. We
also accomplish these tasks for framed links. Our proofs are based on the
Haefliger exact sequence for groups of links and the theory of Lie algebras.Comment: 16 page
DNA double helices for single molecule electronics
The combination of self-assembly and electronic properties as well as its
true nanoscale dimensions make DNA a promising candidate for a building block
of single molecule electronics. We argue that the intrinsic double helix
conformation of the DNA strands provides a possibility to drive the electric
current through the DNA by the perpendicular electric (gating) field. The
transistor effect in the poly(G)-poly(C) synthetic DNA is demonstrated within a
simple model approach. We put forward experimental setups to observe the
predicted effect and discuss possible device applications of DNA. In
particular, we propose a design of the single molecule analog of the Esaki
diode.Comment: 4 pages, 4 figur
Spin-dependent pump current and noise in an adiabatic quantum pump based on domain walls in a magnetic nanowire
We study the pump current and noise properties in an adiabatically modulated
magnetic nanowire with double domain walls (DW). The modulation is brought
about by applying a slowly oscillating magnetic and electric fields with a
controllable phase difference. The pumping mechanism resembles the case of the
quantum dot pump with two-oscillating gates. The pump current, shot noise, and
heat flow show peaks when the Fermi energy matches with the spin-split resonant
levels localized between the DWs. The peak height of the pump current is an
indicator for the lifetime of the spin-split quasistationary states between the
DWs. For sharp DWs, the energy absorption from the oscillating fields results
in side-band formations observable in the pump current. The pump noise carries
information on the correlation properties between the nonequilibrium electrons
and the quasi-holes created by the oscillating scatterer. The ratio between the
pump shot noise and the heat flow serves as an indicator for quasi-particle
correlation.Comment: 18 pages, 5 figure
Hakikat Politik Dinasti Dari Perspektif Filsafat Sangkan Paraning Dumadi Dalam Bingkai Pancasila
Sekalipun pemilihan umum baru akan berlangsung pada tahun 2024, dinamika politik di Indonesia telah mulai memanas sejak pertengahan tahun 2022. Puncaknya di tahun 2023, pada saat Gibran Rakabuming Raka mendapatkan ‘tiket’ dicalonkan sebagai wakil presiden melalui rangkaian prahara Mahkamah Konstitusi, yang diyakini oleh banyak orang sebagai proses politik dinasti. Makalah ini meninjau hakikat politik dinasti dengan menggunakan pendekatan filsafat masyarakat orang Jawa, yaitu ‘sangkan paraning dumadi’, yang salah satu maknanya adalah mengingatkan manusia tentang dari mana ia berasal dan ke mana dia akan kembali. Filsafat sangkan paraning dumadi hidup dalam nilai-nilai Pancasila yang merupakan hasil kristalisasi konsep, nilai, etika dan moral yang digali dari bangsa Indonesia yang majemuk. Hakikat politik dinasti itu adalah upaya melanggengkan politik kekuasaan, dengan menggunakan upaya neopatrimonialistik, dalam tangan sekelompok orang, yang merasa paling benar, paling adil, dan bahkan telah lupa akan makna hidup dan tujuannya. Politik dinasti jelas bertentangan dengan filsafat sangkan paraning dumadi yang hidup dalam nilai-nilai Pancasila, karena mengingkari Tuhan sebagai sumber, pusat alam semesta dan kehidupan, serta akhir dari segalanya. Politik dinasti dalam praktiknya tidak luput dari tindakan yang menghalalkan segala cara dalam upaya mencapai kedudukan dan kesenangan, sehingga tidak menghiraukan nilai-nilai Ketuhanan. Tidak salah jika dalam persepsi sebagian besar masyarakat, praktik politik dinasti adalah salah satu penyebab utama maraknya korupsi, karena lebih mementingkan politik daripada kepentingan rakyat
Effect of Cash Conversion Cycle, Firm Size, and Firm Age to Profitability
This study aims to provide empirical evidence about effect of cash conversion cycle, firm size, and firm age to profitability. This study uses a quantitative approach, data collection techniques using purposive sampling method. The population in this research is manufacturing companies listed in Indonesia Stock Exchange (BEI) in the period 2012-2014 with a total sample of 101 companies and a total of as many as 303 samples of whole observation observation. This study uses panel data regression. This study was conducted to analyze the effect of the cash conversion cycle, firm size and age of the company to profitability by manufacturing companies using panel data through eviews 7.0. Establishment of a model in this study there are three models, namely common effect, fixed effect model and random effect model. Selection of the best model there are three, namely chow test, Hausman test, and langrangge multiplier. The results showed that the variable cash conversion cycle, firm size, firm age and positive effect on the variable return on assets. Variable leverage as control variables have no effect on the variable return on assets
Non-adiabatic Current Excitation in Quantum Rings
We investigate the difference in the response of a one-dimensional
semiconductor quantum ring and a finite-width ring to a strong and short-lived
time-dependent perturbation in the THz regime. In both cases the persistent
current is modified through a nonadiabatic change of the many-electron states
of the system, but by different mechanisms in each case.Comment: LaTeX, 5 pages with 6 embedded postscript figures, submitted to 20th
Nordic Semiconductor Meeting, Tampere (2003
Energy Requirement of Control: Comments on Szilard's Engine and Maxwell's Demon
In mathematical physical analyses of Szilard's engine and Maxwell's demon, a
general assumption (explicit or implicit) is that one can neglect the energy
needed for relocating the piston in Szilard's engine and for driving the trap
door in Maxwell's demon. If this basic assumption is wrong, then the
conclusions of a vast literature on the implications of the Second Law of
Thermodynamics and of Landauer's erasure theorem are incorrect too. Our
analyses of the fundamental information physical aspects of various type of
control within Szilard's engine and Maxwell's demon indicate that the entropy
production due to the necessary generation of information yield much greater
energy dissipation than the energy Szilard's engine is able to produce even if
all sources of dissipation in the rest of these demons (due to measurement,
decision, memory, etc) are neglected.Comment: New, simpler and more fundamental approach utilizing the physical
meaning of control-information and the related entropy production. Criticism
of recent experiments adde
Detection of spin polarized currents in quantum point contacts via transverse electron focusing
It has been predicted recently that an electron beam can be polarized when it
flows adiabatically through a quantum point contact in a system with spin-orbit
interaction. Here, we show that a simple transverse electron focusing setup can
be used to detect such polarized current. It uses the amplitude's asymmetry of
the spin-split transverse electron focusing peak to extract information about
the electron's spin polarization. On the other hand, and depending on the
quantum point contact geometry, including this one-body effect can be important
when using the focusing setup to study many-body effects in quantum point
contacts.Comment: 5 pages, 5 figure
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