10,967 research outputs found
Domain Adaptive Neural Networks for Object Recognition
We propose a simple neural network model to deal with the domain adaptation
problem in object recognition. Our model incorporates the Maximum Mean
Discrepancy (MMD) measure as a regularization in the supervised learning to
reduce the distribution mismatch between the source and target domains in the
latent space. From experiments, we demonstrate that the MMD regularization is
an effective tool to provide good domain adaptation models on both SURF
features and raw image pixels of a particular image data set. We also show that
our proposed model, preceded by the denoising auto-encoder pretraining,
achieves better performance than recent benchmark models on the same data sets.
This work represents the first study of MMD measure in the context of neural
networks
Interferometric mapping of Magnetic fields: G30.79 FIR 10
We present polarization maps of G30.79 FIR 10 (in W43) from thermal dust
emission at 1.3 mm and from CO J= line emission. The observations were
obtained using the Berkeley-Illinois-Maryland Association array in the period
2002-2004. The G30.79 FIR 10 region shows an ordered polarization pattern in
dust emission, which suggests an hourglass shape for the magnetic field. Only
marginal detections for line polarization were made from this region.
Application of the Chandrashkar-Fermi method yielded mG
and a statistically corrected mass to magnetic flux ratio , or essentially critical.Comment: 11 pages, 2 Figures, Published in Ap
Iron Intercalation in Covalent-Organic Frameworks: A Promising Approach for Semiconductors
Covalent-organic frameworks (COFs) are intriguing platforms for designing
functional molecular materials. Here, we present a computational study based on
van der Waals dispersion-corrected hybrid density functional theory (DFT-D) to
design boroxine-linked and triazine-linked COFs intercalated with Fe. Keeping
the original symmetry of the pristine COF (COF-Fe-0), we have
computationally designed seven new COFs by intercalating Fe atoms between two
organic layers. The equilibrium structures and electronic properties of both
the pristine and Fe-intercalated COF materials are investigated here. We
predict that the electronic properties of COFs can be fine tuned by adding Fe
atoms between two organic layers in their structures. Our calculations show
that these new intercalated-COFs are promising semiconductors. The effect of Fe
atoms on the electronic band structures and density of states (DOSs) has also
been investigated using the aforementioned DFT-D method. The contribution of
the -subshell electron density of the Fe atoms plays an important role in
improving the semiconductor properties of these new materials. These
intercalated-COFs provide a new strategy to create semi-conducting materials
within a rigid porous network in a highly controlled and predictable manner.Comment: 39 pages. arXiv admin note: text overlap with arXiv:1703.0261
Land Use Influence on the Characteristics of Groundwater Inputs to the Great Bay Estuary, New Hampshire
This research examines the sources and factors affecting nutrient-laden groundwater discharge to the Great Bay Estuary. To further understand this relationship, examination of groundwater residence time, a review of historic land uses, and nitrate source tracking strategies were used. Seven submarine groundwater discharge (SGD) sites were selected, and groundwater monitoring networks were installed to examine the relationship between land use and groundwater quality at the discharge zones. Field activities were performed in the summer and fall of 2003 and 2004. Estuarine water intrusion in groundwater discharge samples confounded the analyses for major ion chemistry and boron isotopes. CFC-derived and modeled groundwater ages in the study area averaged 23.2 years (±15.0 years). CFC analysis enabled correlation of nitrate concentrations at the SGD sites with the historic land use coverage for the years 1974 (for most of the sites) or 1962 (SGD 58.4). Two types of correlation were made: 1) between the agricultural and residential land use for all observed nitrate concentrations in the recharge areas, and 2) correlation with the nitrate concentrations between developed and undeveloped land uses. Both statistical correlations (Kendall’s Tau and Spearman’s Rho) indicated a connection between the increase of residential land use of the last three decades with the high nitrate-bearing groundwater discharging to the Great Bay (NH). The geochemical composition of the SGD water was also investigated by using simple mixing models that attempted to explain the water chemistry characteristics of the targeted SGD sites. Based on these models it was concluded that overburden groundwater comprises 75% to 95% of the groundwater discharging at the SGD sites. A significant correlation (Tau’s, p=0.021) between nitrate-bearing groundwater and CFCderived groundwater ages was detected supporting the hypothesis that high nitrate bearing groundwater will be discharged to the Great Bay in the near future accounting for the increase of residential land use of 1990’s. Continuous monitoring of SGD sites was suggested to be included as part of the periodic environmental quality monitoring activities of the Great Bay. Long-term step-wise sampling for groundwater dating is required to develop a stronger chronological evolution of groundwater nitrate inputs. Further research should concentrate on detailing the overburden water chemistry, flow paths, and nitrogen loading characteristics
The Nature of the Peculiar Virgo Cluster Galaxies NGC 4064 and NGC 4424
We present a detailed study of the peculiar HI-deficient Virgo cluster spiral
galaxies NGC 4064 and NGC 4424, using CO 1-0 interferometry, optical
imaging and integral-field spectroscopic observations, in order to learn what
type of environmental interactions have afected these galaxies. Optical imaging
reveals that NGC 4424 has a strongly disturbed stellar disk, with banana-shaped
isophotes and shells. NGC 4064, which lies in the cluster outskirts, possesses
a relatively undisturbed outer stellar disk and a central bar. In both galaxies
H-alpha emission is confined to the central kiloparsec. CO observations reveal
bilobal molecular gas morphologies, with H-alpha emission peaking inside the CO
lobes, implying a time sequence in the star formation process.Gas kinematics
reveals strong bar-like non-circular motions in the molecular gas in both
galaxies, suggesting that the material is radially infalling. In NGC 4064 the
stellar kinematics reveal strong bar-like non-circular motions in the central 1
kpc. On the other hand, NGC 4424 has extremely modest stellar rotation
velocities (Vmax ~ 30 km s-1), and stars are supported by random motions as far
out as we can measure it. The observations suggest that the peculiarities of
NGC 4424 are the result of an intermediate-mass merger plus ram pressure
stripping. In the case of NGC 4064, the evidence suggests an already stripped
"truncated/normal" galaxy that recently suffered a minor merger or tidal
interaction with another galaxy. We propose that galaxies with
"truncated/compact" H-alpha morphologies such as these are the result of the
independent effects of ram pressure stripping, which removes gas from the outer
disk, and gravitational interactions such as mergers, which heat stellar disks,
drive gas to the central kpc and increase the central mass concentrations.Comment: 42 pages, 21 figure
Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish Assemblages
The use of river-types is of practical value, serving as groups for which
assessment procedures can be developed and applied. An abiotic typology
was set by the Portuguese Water Agency, mainly based on 6 major
morphoclimatic regions. However, to be biologically meaningful, this typology
should fit the distribution patterns of the biological quality elements
communities proposed in Water Framework Directive under the lowest
possible human pressure. This study aimed to identify and characterize
fish-based geographical groups for continental Portugal and their environmental
and geographical discriptors, using taxonomic and functional
traits. Sampling took place between 2004 and 2006 during Spring. Fish
fauna from 155 reference sites was analysed using a multivariate
approach. Cluster Analysis on fish composition identified 10 fish-groups,
expressing a clear correspondence to the river basin level, due to the
restrict basin distribution of many species. Groups showed a wider aggregation
in 4 regions with a larger geographical correspondence, statistically
supported by Similarity Analysis, both on fish composition and mostly on
fish metrics/guilds. Principal Components Analysis revealed major environmental
drivers associated to fish-groups and fish-regions. Fish-groups
were hierarchically grouped over major and local regions, expressing a
large-scale response to a North-South environmental gradient defined by
temperature, precipitation, mineralization and altitude, and a regional scale
response mainly to drainage area and flow discharge. From North to
South, fish-regions were related to the morphoclimatic regions. Results
contributed to reduce redundance in abiotic river-types and set the final
typology for Portuguese rivers, constituting a fundamental tool for planning
and managing water resources
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