3,106 research outputs found
Evidence for Charging Effects in CdTe/CdMgTe Quantum Point Contacts
Here we report on fabrication and low temperature magnetotransport
measurements of quantum point contacts patterned from a novel two-dimensional
electron system - CdTe/CdMgTe modulation doped heterostructure. From the
temperature and bias dependence we ascribe the reported data to evidence for a
weakly bound state which is naturally formed inside a CdTe quantum
constrictions due to charging effects. We argue that the spontaneous
introduction of an open dot is responsible for the replacement of flat
conductance plateaus by quasi-periodic resonances with amplitude less than
2e^{2}/h, as found in our system. Additionally, below 1 K a pattern of weaker
conductance peaks, superimposed upon wider resonances, is also observed.Comment: 4 pages, 4 figure
Low-effort place recognition with WiFi fingerprints using deep learning
Using WiFi signals for indoor localization is the main localization modality
of the existing personal indoor localization systems operating on mobile
devices. WiFi fingerprinting is also used for mobile robots, as WiFi signals
are usually available indoors and can provide rough initial position estimate
or can be used together with other positioning systems. Currently, the best
solutions rely on filtering, manual data analysis, and time-consuming parameter
tuning to achieve reliable and accurate localization. In this work, we propose
to use deep neural networks to significantly lower the work-force burden of the
localization system design, while still achieving satisfactory results.
Assuming the state-of-the-art hierarchical approach, we employ the DNN system
for building/floor classification. We show that stacked autoencoders allow to
efficiently reduce the feature space in order to achieve robust and precise
classification. The proposed architecture is verified on the publicly available
UJIIndoorLoc dataset and the results are compared with other solutions
A Comparative Review on Ombuds: Recommendations of Action for the Turkish Ombudsman and Guidelines for the Ombudsman and Public Authorities
Simulated Greenland Surface Mass Balance in the GISS ModelE2 GCM: Role of the Ice Sheet Surface
The rate of growth or retreat of the Greenland and Antarctic ice sheets remains a highly uncertain component of future sea level change. Here we examine the simulation of Greenland ice sheet surface mass balance (GrIS SMB) in the NASA Goddard Institute for Space Studies (GISS) ModelE2 General Circulation Model (GCM). GCMs are often limited in their ability to represent SMB compared with polarregion Regional Climate Models (RCMs). We compare ModelE2 simulated GrIS SMB for presentday (19962005) simulations with fixed ocean conditions, at a spatial resolution of 2 latitude by 2.5 longitude (~200 km), with SMB simulated by the Modle Atmosphrique Rgionale (MAR) RCM (19962005 at a 25 km resolution). ModelE2 SMB agrees well with MAR SMB on the whole, but there are distinct spatial patterns of differences and large differences in some SMB components. The impact of changes to the ModelE2 surface are tested, including a subgridscale representation of SMB with surface elevation classes. This has a minimal effect on ice sheetwide SMB, but corrects local biases. Replacing fixed surface albedo with satellitederived values and an agedependent scheme has a larger impact, increasing simulated melt by 60100%. We also find that lower surface albedo can enhance the effects of elevation classes. Reducing ModelE2 surface roughness length to values closer to MAR reduces sublimation by ~50%. Further work is required to account for meltwater refreezing in ModelE2, and to understand how differences in atmospheric processes and model resolution influence simulated SMB
C.H.E. Det Optimisme, disiplin dan wawasan
Optimisme, disiplin dan wawasan. Tiga perkataan ini cukup untuk menggambarkan kualiti beliau. Optimisme – kepercayaan teguh beliau bahawa cita-cita yang diisi
akan menatijahkan kejayaan, dan tanpa pengisian, cita-cita tersebut sekadar tinggal angan-angan. Disiplin – tunjang prinsip beliau bahawa usaha ke arah kecemerlangan
menuntut sikap dan watak yang khusus, dan tanpa disiplin, kegagalan pasti menanti. Wawasan – pandangan jauh beliau bahawa kejayaan sebenar terletak kepada keupayaan untuk melestarikan pencapaian di atas garis masa yang panjang. 87 tahun usia yang bakal dilewati tanggal 20 Disember kelak, dan tiga kualiti ini – DISIPLIN, OPTIMISME dan WAWASAN terus segar mendasari penyandang keempat jawatan Perdana Menteri Malaysia, Tun Dr. Mahathir Mohamad
Greenland Ice Sheet Surface Melt and Its Relation to Daily Atmospheric Conditions
Melt area is one of the most reliably monitored variables associated with surface conditions over the full Greenland Ice Sheet (GrIS). Surface melt is also an important indicator of surface mass balance and has potential relevance to the ice sheet's global sea level contribution. Melt events are known to be spatially heterogeneous and have varying time scales. To understand the forcing mechanisms, it is necessary to examine the relation between the existing conditions and melt area on the time scales that melt is observed. Here, we conduct a regression analysis of atmospheric reanalysis variables including sea level pressure, near-surface winds, and components of the surface energy budget with surface melt. The regression analysis finds spatial heterogeneity in the associated atmospheric circulation conditions. For basins in the southern GrIS, there is an association between melt area and high pressure located south of the Denmark Strait, which allows for southerly flow over the western half of the GrIS. Instantaneous surface melt over northern basins is also associated with low pressure over the central Arctic. Basins associated with persistent summer melt in the southern and western GrIS are associated with the presence of an enhanced cloud cover, a resulting decreased downwelling solar radiative flux, and an enhanced downwelling longwave radiative flux. This contrasts with basins to the north and east, where an increased downwelling solar radiative flux plays a more important role in the onset of a melt event. The analysis emphasizes the importance of daily variability in synoptic conditions and their preferred association with melt events
Fluctuations of an Atomic Ledge Bordering a Crystalline Facet
When a high symmetry facet joins the rounded part of a crystal, the step line
density vanishes as sqrt(r) with r denoting the distance from the facet edge.
This means that the ledge bordering the facet has a lot of space to meander as
caused by thermal activation. We investigate the statistical properties of the
border ledge fluctuations. In the scaling regime they turn out to be
non-Gaussian and related to the edge statistics of GUE multi-matrix models.Comment: Version with major revisions -- RevTeX, 4 pages, 2 figure
Complex bounds for multimodal maps: bounded combinatorics
We proved the so called complex bounds for multimodal, infinitely
renormalizable analytic maps with bounded combinatorics: deep renormalizations
have polynomial-like extensions with definite modulus. The complex bounds is
the first step to extend the renormalization theory of unimodal maps to
multimodal maps.Comment: 20 pages, 3 figure
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