8,376 research outputs found
Nonadiabatic Geometric Quantum Computation Using A Single-loop Scenario
A single-loop scenario is proposed to realize nonadiabatic geometric quantum
computation. Conventionally, a so-called multi-loop approach is used to remove
the dynamical phase accumulated in the operation process for geometric quantum
gates. More intriguingly, we here illustrate in detail how to use a special
single-loop method to remove the dynamical phase and thus to construct a set of
universal quantum gates based on the nonadiabatic geometric phase shift. The
present scheme is applicable to NMR systems and may be feasible in other
physical systems.Comment: 4 pages, 3 figure
Chaotic Properties of Subshifts Generated by a Non-Periodic Recurrent Orbit
The chaotic properties of some subshift maps are investigated. These
subshifts are the orbit closures of certain non-periodic recurrent points of a
shift map. We first provide a review of basic concepts for dynamics of
continuous maps in metric spaces. These concepts include nonwandering point,
recurrent point, eventually periodic point, scrambled set, sensitive dependence
on initial conditions, Robinson chaos, and topological entropy. Next we review
the notion of shift maps and subshifts. Then we show that the one-sided
subshifts generated by a non-periodic recurrent point are chaotic in the sense
of Robinson. Moreover, we show that such a subshift has an infinite scrambled
set if it has a periodic point. Finally, we give some examples and discuss the
topological entropy of these subshifts, and present two open problems on the
dynamics of subshifts
Erosion-induced massive organic carbon burial and carbon emission in the Yellow River basin, China
Soil erosion and terrestrial deposition of soil organic carbon (SOC) can
potentially play a significant role in global carbon cycling. Assessing the
redistribution of SOC during erosion and subsequent transport and burial is
of critical importance. Using hydrological records of soil erosion and
sediment load, and compiled organic carbon (OC) data, estimates of the eroded
soils and OC induced by water in the Yellow River basin during the period
1950–2010 were assembled. The Yellow River basin has experienced intense
soil erosion due to combined impact of natural process and human activity.
Over the period, 134.2 ± 24.7 Gt of soils and 1.07 ± 0.15 Gt of
OC have been eroded from hillslopes based on a soil erosion rate of
1.7–2.5 Gt yr<sup>−1</sup>. Approximately 63% of the eroded soils were
deposited in the river system, while only 37% were discharged into the
ocean. For the OC budget, approximately 0.53 ± 0.21 Gt (49.5%) was
buried in the river system, 0.25 ± 0.14 Gt (23.5%) was delivered
into the ocean, and the remaining 0.289 ± 0.294 Gt (27%) was
decomposed during the erosion and transport processes. This validates the
commonly held assumption that 20–40% of the eroded OC would be oxidized
after erosion. Erosion-induced OC redistribution on the landscape likely
represented a carbon source, although a large proportion of OC was buried. In
addition, about half of the terrestrially redeposited OC (49.4%) was
buried behind dams, revealing the importance of dam trapping in sequestering
the eroded OC. Although several uncertainties need to be better constrained,
the obtained budgetary results provide a means of assessing the
redistribution of the eroded OC within the Yellow River basin. Human
activities have significantly altered its redistribution pattern over the
past decades
Sensitivity of various body indices and visceral adiposity index in predicting metabolic syndrome among Chinese patients with adult growth hormone deficiency
Mineralogical and geochemical study of carp otoliths from Baiyangdian Lake and Miyun Water Reservoir in China
Carp otoliths from two different freshwaters (Baiyangdian Lake and Miyun Water Reservoir) were mineralogically and chemically analyzed. The water quality standard of Miyun Water Reservoir is Grade 2 which is much better than the Grade 5 of Baiyangdian Lake. The aim of this study was to examine the differences in otoliths in mineralogy and chemistry from the two sites with quite different qualities. All the analyzed carps showed lapillus and sagitta otoliths made of aragonite, except for B-22 (from Baiyangdian Lake) whose lapillus consisted of vaterite and sagitta consisted of aragonite and vaterite; all asteriscus are composed of vaterite. It is inferred that the occurrence of vaterictic otoliths is linked to poor water quality. Chemical analysis showed that significant difference of Pb concentration between sites was tested by t-test of the compare means (t-test comparison: t = 2.043, P<0.05). While the sitespecific differences of the other metals were not significant. In addition, a significant difference of Sn concentration was tested as well (t-test comparison: t = 2.652, P<0.05). Average content of lapilli Pb is consistent with the water dissolved Pb measurement, with higher dissolved Pb concentration in Baiyangdian Lake relative to the Miyun Water Reservoir.Key words: Carp otoliths, water quality, mineralogy, chemistry, Pb
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