bluuebunny/crossref_metadata_2025 huggingface dataset:
OH column abundance over Table Mountain Facility, California: AM‐PM diurnal asymmetry
Authors: Li King‐Fai , Cageao Richard P. , Karpilovsky Elliott M. , Mills Franklin P. , Yung Yuk L. , Margolis Jack S. , Sander Stanley P.
Published: July 2005

Observations of the OH column abundance have been made by the Fourier Transform Ultraviolet Spectrometer at the JPL Table Mountain Facility (TMF) near Los Angeles since July 1997. In the January 1998–December 2003 data set we used five OH lines to derive the OH column abundance in the atmosphere. This data set was used to quantify the OH morning/afternoon asymmetry (AMPMDA). An analysis of summer and winter data showed that the daily OH maximum occurred 26–36 minutes after solar transit. This phase lag appears to be the primary reason why OH in the afternoon is larger than at corresponding solar zenith angles in the morning throughout the year. A simple heuristic model suggests that the asymmetry is a direct consequence of the finite lifetime of OH. Comparison of the TMF data with earlier results from Fritz Peak Observatory, Colorado, by Burnett et al. reveals significant differences in the behavior of the AMPMDA between the two sites.
Effect of particle size distributions on the retrieval of ice cloud properties
Authors: Han Qingyuan , Zeng Jian , Kuo Kwo‐Sen , Chen Hui , Smith Erik
Published: July 2005

Various measured size distributions obtained from aircraft measurements at different regions and seasons are used in the retrieval algorithms for ice cloud properties by several major satellite instruments such as MODIS, CERES and VIIRS. These measured size distributions are characterized by one parameter: effective size (diameter or radius). This study shows that the adoption of such measured size distributions leads to inconsistent results in retrieved cloud properties because neglecting the effect of effective variances causes non‐monotonic relations between crystal size and single scattering properties. We also show that single scattering properties of most observed size distributions of hexagonal columns can be adequately characterized by effective radius and effective variance. Therefore, in remote sensing of ice cloud properties, theoretical size distributions with explicitly assumed effective variances should be used, similar to the practice adopted for water clouds.
Radiation energy measured at earthquake source
Authors: Fukuyama Eiichi
Published: July 2005

We propose a new radiation energy, which is defined as an energy radiation measured close to the source. This energy enables us to rigorously handle the energy emitted not only from an earthquake but also from asperities of an earthquake. Therefore we can discuss a spatial variation of the radiation energy on the fault and compare it with the fracture energy distribution that consumed during the rupture. It should be noted that this new radiation energy includes the energy due to near field deformation. The difference between the traditional radiation energy and this new radiation energy is proven to be equal to the static strain energy change.
Contemporary climate change in the Amazon
Authors: Chagnon F. J. F. , Bras R. L.
Published: July 2005

Deforestation of the entire Amazon basin — the catastrophe scenario — is projected to result in regional decreases of precipitation and evaporation, potentially leading to sustained desertification. However, current levels and patterns of Amazon deforestation actually enhance mass and energy transfers between the land and the atmosphere through the creation of thermally driven circulations. The climatological effects of these circulations have long been thought to be inconsequential (e.g., Negri et al., 2004). In contrast, we find here that current deforestation causes a dramatic change in climatological rainfall occurrence patterns; high‐resolution satellite precipitation measurements show significantly more rainfall occurrences (p ≤ 0.0001) over deforested areas. Moreover, a 75 year‐long rain gauge record shows a long‐term shift in the seasonality of precipitation that is concurrent with deforestation. These findings suggest that current deforestation in the Amazon has already altered the regional climate. Such changes have implications for regional ecosystem dynamics, but may also affect global climatic patterns through tropospheric teleconnections.
On the definition of El Niño and associated seasonal average U.S. weather anomalies
Authors: Larkin Narasimhan K. , Harrison D. E.
Published: July 2005

A new NOAA definition of El Niño identifies a number of additional El Niño seasons beyond those conventionally agreed. These additional seasons are characterized by SST anomalies primarily in the western central equatorial Pacific. We show here that the seasonal weather anomalies over the U.S. associated with these additional Dateline El Niño seasons are substantially different from those associated with conventional El Niño seasons. Although some regions have similar associated anomalies, most of the major regional anomalies are quite different. Treating the two as a single phenomenon yields weaker overall seasonal weather associations and does not take advantage of the stronger associations available when the two are treated separately.
Winter climate variability changes over Europe and the Mediterranean region under increased greenhouse conditions
Authors: Rodríguez‐Fonseca B. , Sánchez E. , Arribas A.
Published: July 2005

Regional changes in seasonal precipitation over Europe have been analysed in two 30‐year simulations (current climate and A2‐SRES increased greenhouse‐gases scenario) using a Global (GCM) and a Regional Climate Model (RCM). The analysis of the simulations is approached using maximum covariance analysis (MCA) to establish the relationship between seasonal precipitation over the European‐Mediterranean region and the North Atlantic atmospheric patterns in the winter season. Our results show that the leading MCA modes in the control simulation are similar for both models and agree well with previous studies using observations. The analysis of the A2‐SRES scenario RCM results show changes with respect to the control simulation: the first two modes present slight shifts in their centres of action, whereas the third mode resembles more closely what is obtained in current climate simulations. Some differences, specially for the third mode, are obtained when comparing the RCM and the GCM simulations.
Relating near‐Earth observations of an interplanetary coronal mass ejection to the conditions at its site of origin in the solar corona
Authors: Fazakerley A. N. , Harra L. K. , Culhane J. L. , van Driel‐Gesztelyi L. , Lucek E. , Matthews S. A. , Owen C. J. , Mazelle C. , Balogh A. , Rème H.
Published: July 2005

A halo coronal mass ejection (CME) was detected on January 20, 2004. We use solar remote sensing data (SOHO, Culgoora) and near‐Earth in situ data (Cluster) to identify the CME source event and show that it was a long duration flare in which a magnetic flux rope was ejected, carrying overlying coronal arcade material along with it. We demonstrate that signatures of both the arcade material and the flux rope material are clearly identifiable in the Cluster and ACE data, indicating that the magnetic field orientations changed little as the material traveled to the Earth, and that the methods we used to infer coronal magnetic field configurations are effective.
Observations of energetic neutral oxygen by IMAGE/HENA and Geotail/EPIC
Authors: Lui A. T. Y. , Brandt P. C. , Mitchell D. G.
Published: July 2005

Energetic neutral oxygen emissions from two satellites, IMAGE and Geotail, are examined during a magnetic storm interval on 2001 November 24–25. These two satellite observations provide different viewing perspectives of the energetic neutral emissions from the Earth's magnetosphere. IMAGE has a high inclination orbit while Geotail has a low one. Overlapping energy range of energetic neutral oxygen occurs for HENA on IMAGE and EPIC on Geotail. Quantitative comparison of oxygen energy spectra during this storm period indicates that viewing perspective plays an important role in the total intensity measured. This study constitutes the first quantitative inter‐spacecraft comparison of energetic neutral oxygen intensity.
In situ observations of a solar wind compression‐induced hot plasma injection in Saturn's tail
Authors: Bunce E. J. , Cowley S. W. H. , Wright D. M. , Coates A. J. , Dougherty M. K. , Krupp N. , Kurth W. S. , Rymer A. M.
Published: July 2005

During the Saturn orbit insertion (SOI) fly‐through of the Cassini spacecraft, Saturn's magnetosphere underwent a significant corotating interaction region (CIR) related compression. Such compressions have recently been suggested to produce rapid bursts of tail reconnection, enhanced Saturn kilometric radiation (SKR), and consequent auroral dynamics. On the outbound pass the spacecraft became engulfed by hot plasma, associated with a reduction in field strength, and a change in orientation indicative of a dipolarisation. Concurrently, a substantial enhancement in SKR emissions took place, together with a disruption of the typical planetary modulation. We suggest this is the first in situ evidence of compression‐related tail collapse via magnetic reconnection and hot plasma acceleration in Saturn's magnetotail.
Energy spectra of ∼170–360 keV electron microbursts measured by the Korean STSAT‐1
Authors: Lee J.‐J. , Parks G. K. , Min K. W. , Kim H. J. , Park J. , Hwang J. , McCarthy M. P. , Lee E. , Ryu K. S. , Lim J. T. , Sim E. S. , Lee H. W. , Kang K. I. , Park H. Y.
Published: July 2005

Energy spectra of electron microbursts in the energy range 170–360 keV have been measured in the outer radiation zone by the low‐altitude (680 km), polar‐orbiting Korean satellite STSAT‐1. These electrons are the lower energy population of relativistic microbursts. Our observations show microburst energy spectra of precipitated electrons inside the loss cone (precipitated) have higher e‐folding energies during disturbed times than quiet times. The loss cone at these energies is empty except when microbursts abruptly appear and fill the loss cone in less than 50 msec. This fast pitch angle diffusion requires diffusion coefficients larger than ∼3.5 × 10−2 rad2/sec, while ∼1.5 × 10−5 rad2/sec was proposed by a wave particle interaction theory. The source of microbursts remains unknown as our observations are not adequately explained by wave and particle resonant interaction models.
Isotopic view on nitrate loss in Antarctic surface snow
Authors: Blunier Thomas , Floch Grégoire L. , Jacobi Hans‐Werner , Quansah Emmanuel
Published: July 2005

Massive post‐depositional processes alter the nitrate concentration in polar firn where the annual snow accumulation is low. This hinders a direct atmospheric interpretation of the ice core nitrate record. Fractionation of nitrate isotopes during post‐depositional nitrate loss may allow estimating the amount of nitrate loss in the past. We measured δ15N of nitrate in two Antarctic surface cores from the Dome C area. In concert with the known concentration decrease with depth we observe an increase in the isotopic signature. Assuming a Rayleigh type process we find an isotope effect of ɛ = −54‰. We measured the fractionation factor for photolysis in the laboratory and obtained ɛ = −11.7 ± 1.4‰. As the observed fractionation factor in the firn is much lower this rules out that photolysis in the surface snow is the main process leading to the dramatic nitrate loss in the top centimeters of the firn.
The Antarctic Circumpolar Productivity Belt
Authors: Ito T. , Parekh P. , Dutkiewicz S. , Follows M. J.
Published: July 2005

We illustrate the mechanisms controlling the spatial patterns of biological productivity in the Southern Ocean using a coupled, physical‐biogeochemical‐ecological model. The model captures a belt of enhanced export production, figuratively termed as the Antarctic Circumpolar Productivity Belt. As observed, there is a maximum in silica export to the south of the peak in the organic carbon export. We show that the meridional and zonal structures of the productivity belt are strongly controlled by the residual mean circulation; the net effect of the Ekman flow and the eddy‐induced circulation. The belt of maximum silica export coincides with the region of residual mean upwelling which supplies silica, iron and phosphate to the surface. The peak of organic carbon export is shifted to the north and is located at the boundary between iron and phosphate limited regimes. Here the equatorward residual mean flow supplies phosphate and aeolian deposition provides iron.
A method to infer short wave absorption due to aerosols using satellite remote sensing
Authors: Satheesh S. K. , Srinivasan J.
Published: July 2005

Retrieval of aerosol absorption using satellite remote sensing is an important but difficult problem. Earlier studies have demonstrated that the effect of aerosol absorption is small over surfaces with low reflectance, but is important over surfaces with large surface reflectance. Here, we propose a method to infer the short wave absorption characteristics of aerosols using satellite remote sensing. The proposed method exploits high surface reflectance of continents (especially deserts) and absorbing nature of aerosols. The advent of multi‐spectral satellites such as MODIS provides an excellent opportunity to infer the regional distribution of aerosol absorption. The method is validated using ground‐based measurements. The overall error in the inferred single scattering albedo is ±0.02 and ±0.03 corresponding to surface reflectance of 0.15 and 0.25 respectively.
Climatic and biogeochemical effects of a galactic gamma ray burst
Authors: Melott Adrian L. , Thomas Brian C. , Hogan Daniel P. , Ejzak Larissa M. , Jackman Charles H.
Published: July 2005

It is likely that one or more gamma ray bursts within our galaxy have strongly irradiated the Earth in the last Gy. This produces significant atmospheric ionization and dissociation, resulting in ozone depletion and DNA‐damaging ultraviolet solar flux reaching the surface for up to a decade. Here we show the first detailed computation of two other significant effects. Visible opacity of NO2 is sufficient to reduce solar energy at the surface up to a few percent, with the greatest effect at the poles, which may be sufficient to initiate glaciation. Rainout of dilute nitric acid could have been important for a burst nearer than our conservative “nearest burst”. These results support the hypothesis that the characteristics of the Late Ordovician mass extinction are consistent with GRB initiation.
High aerosol load over the Pearl River Delta, China, observed with Raman lidar and Sun photometer
Authors: Ansmann Albert , Engelmann Ronny , Althausen Dietrich , Wandinger Ulla , Hu Min , Zhang Yuanghang , He Qianshan
Published: July 2005

Height–resolved data of the particle optical properties, the vertical extend of the haze layer, aerosol stratification, and the diurnal cycle of vertical mixing over the Pearl River Delta in southern China are presented. The observations were performed with Raman lidar and Sun photometer at Xinken (22.6°N, 113.6°E) near the south coast of China throughout October 2004. The lidar run almost full time on 21 days. Sun photometer data were taken on 23 days, from about 0800 to 1700 local time. The particle optical depth (at about 533–nm wavelength) ranged from 0.3–1.7 and was, on average, 0.92. Ångström exponents varied from 0.65–1.35 (for wavelengths 380 to 502 nm) and from 0.75–1.6 (for 502 to 1044 nm), mean values were 0.97 and 1.22. The haze–layer mean extinction–to–backscatter ratio ranged from 35–59 sr, and was, on average, 46.7 sr. The top of the haze layer reached to heights of 1.5–3 km in most cases.
Effects of oblique subduction on the 3‐D pattern of small‐scale convection within the mantle wedge
Authors: Honda Satoru , Yoshida Takeyoshi
Published: July 2005

We have developed a 3‐D numerical model of obliquely subducting slab and mantle flow above. Using this model, we explore the effects of oblique subduction on the small‐scale convection within the mantle wedge. We find that the spatial pattern and time dependent characteristics of oblique subduction are similar to those of non‐oblique cases whose subduction speed is the same as the subduction velocity component normal to the strike of subducting slab. This also implies that the axes of rolls of small‐scale convection are nearly normal to the plate boundary, assuming that the plate boundary represents the strike of subducting plate. Only when the back‐arc lithosphere overlying the small‐scale convection moves along the strike of subduction, a significant change of the orientation of roll axes is observed.
An indigenous origin for the South Pole Aitken basin thorium anomaly
Authors: Garrick‐Bethell Ian , Zuber Maria T.
Published: July 2005

The northwest portion of the Moon's South Pole‐Aitken basin contains an anomalously high abundance of thorium as determined by Apollo and Lunar Prospector gamma‐ray spectroscopy. The anomaly's proximity to the antipode of the Imbrium basin has led several investigators to suggest that the anomaly is the result of convergence of thorium‐enriched ejecta from the Imbrium impact. Examination of this complex region with new higher‐resolution thorium data and several other datasets reveals that a convergence of ejecta cannot explain the anomaly. Alternatively, we propose an indigenous and likely ancient source.
Dual‐frequency radar ratio of nonspherical atmospheric hydrometeors
Authors: Matrosov S. Y. , Heymsfield A. J. , Wang Z.
Published: July 2005

Dual‐frequency cloud and precipitation radar systems are being actively developed and installed on different platforms. The use of two radar frequencies (with at least one frequency outside the Rayleigh type of scattering for hydrometeors of interest) allows independent estimates of hydrometeor effective size. With these estimates, radar‐based retrievals of such important parameters as cloud mass content or precipitation rate can be potentially performed with better accuracy compared to single‐ frequency radar measurements. This study presents quantitative assessments of the effects of nonsphericity of ice cloud particles which influence the dual‐frequency ratio used for characteristic size estimates.
On bimodality in warm season soil moisture observations
Authors: Teuling Adriaan J. , Uijlenhoet Remko , Troch Peter A.
Published: July 2005

It has recently been suggested that the bimodality in warm season soil moisture observations in Illinois is evidence of a soil moisture‐precipitation feedback. Other studies however provide little evidence for a strong feedback in this region. Here we show that seasonality in the meteorological conditions in combination with the non‐linearity of the soil moisture response alone can induce this bimodality. The existence of preferred wet and dry soil moisture states may have implications for the understanding and modeling of soil moisture dynamics in mid‐latitude regions.
Specific surface area, density and microstructure of frost flowers
Authors: Domine Florent , Taillandier Anne Sophie , Simpson William R. , Severin Ken
Published: July 2005

Frost flowers often grow on new sea ice. They are thought to have a high specific surface area (SSA) that provides sites for heterogeneous reactions. We have measured the SSA of frost flowers using CH4 adsorption at 77 K and obtained a value of 185 (+80 −50) cm2/g, much lower than inferred by others. Their density is 0.02 g/cm3. We calculate that the total surface area of frost flowers is 1.4 m2 per m2 of ice surface, so that they do not increase the ice surface area significantly. Their role as sites for enhanced heterogeneous reactions should be reconsidered. Frost flowers also commonly grow on fresh water and the saline brine seen on young sea ice is not necessary for their growth. Photo‐ and electro‐micrographs reveal hollow and concave structures, typical of very fast growing crystals. The brine that wicks up frost flowers considerably perturbs their growth.
Stormtime coupling of the ring current, plasmasphere, and topside ionosphere: Electromagnetic and plasma disturbances
Authors: Mishin E. V. , Burke W. J.
Published: July 2005

We compare plasma and field disturbances observed in the ring current/plasmasphere overlap region and in the conjugate ionosphere during the magnetic storm of 5 June 1991. Data come from the Combined Release and Radiation Effects Satellite (CRRES) flying in a geostationary transfer orbit and three satellites of the Defense Meteorological Satellite Program (DMSP) series in Sun‐synchronous polar orbits. In the region between ring current nose structures and the electron plasma sheet, CRRES detected wave‐like features in local electric and magnetic fields, embedded in structured cold plasmas. Mapped to the ionosphere, these fields should reflect structuring within subauroral plasma streams (SAPS). Indeed, during the period of interest, DMSP F8, F9, and F10 satellites observed highly structured SAPS in the evening ionosphere at topside altitudes. They were collocated with precipitating ring current ions, enhanced fluxes of suprathermal electrons and ions, elevated electron temperatures, and irregular plasma density troughs. Overall, these events are similar to electromagnetic structures observed by DMSP satellites within SAPS during recent geomagnetic storms (Mishin et al., 2003, 2004). Their features can be explained in terms of Alfvén and fast magnetosonic perturbations. We developed a scenario for the formation of elevated electron temperatures at the equatorward side of the SAPS. It includes a lower‐hybrid drift instability driven by diamagnetic currents, consistent with strong lower‐ and upper‐hybrid plasma wave activity and intense fluxes of the low‐energy electrons and ions near the ring current's inner edge.
Will solar minimum dim interest in space weather?
Authors: Lanzerotti Louis J.
Published: July 2005

With solar activity decreasing as solar minimum approaches, will public and private interest in space weather effects decrease as well? This question should be of interest to researchers and to those involved with space weather operations. Over the next few years the community should pay close attention to likely diminishing interest by managers in space weather, and the implications for support for space weather research.
Wavelength modulation spectroscopy using novel mechanical light chopper blade designs
Authors: Bhattacharyya Jayeeta , Ghosh Sandip , Arora B. M.
Published: July 2005

We describe two mechanical light chopper blade designs that can be used, with a monochromator and broadband light-source-based spectroscopy setup, to perform wavelength modulation spectroscopy. The left and the right half of a beam emerging from a monochromator would have spectral distributions that are skewed to longer and shorter wavelengths about the central wavelength for positive grating orders. Our two designs, the alternating double-slot blade and the vertical right-angled blade, allow switching between the two halves of the beam front to generate a small periodic variation in the wavelength distribution, enabling wavelength modulation spectroscopy. In contrast to existing methods of wavelength modulation, this technique does not require modification of the monochromator or the light source unit. We analyze the signal waveforms and show how, and under what conditions, wavelength modulation data can be extracted from the alternating signal components measured by the detector. To demonstrate their functioning and applicability, we have performed wavelength-modulated reflectance spectroscopy on epitaxial semiconductor samples using these chopper blades.
Axially open nonradiative structures: An example of single-mode resonator based on the sample holder
Authors: Annino G. , Cassettari M. , Martinelli M.
Published: July 2005

The concept of nonradiative dielectric resonator is generalized in order to include axially open configurations having rotational invariance. The resulting additional nonradiative conditions are established for the different resonance modes on the basis of their azimuthal modal index. An approximate chart of the allowed dielectric and geometrical parameters for the TE011 mode is given. A practical realization of the proposed device based on commercial fused quartz capillary tubes is demonstrated at millimeter wavelengths, together with simple excitation and tuning mechanisms. The observed resonances are characterized in their basic parameters, as well as in the field distribution by means of a finite element method. The predictions of the theoretical analysis are well confirmed, both in the general behavior and in the expected quality factors. The resulting device, in which the sample holder acts itself as single-mode resonating element, combines an extreme ease of realization with state-of-the-art performances. The general benefits of the proposed open single-mode resonators are finally discussed.
Structure of intermediate shocks and slow shocks in a magnetized plasma with heat conduction
Authors: Tsai C. L. , Wu B. H. , Lee L. C.
Published: July 2005

The structure of slow shocks and intermediate shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. This study is an extension of an earlier work [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002)], in which the effects of heat conduction are examined for the case that the tangential magnetic fields on the two side of initial current sheet are exactly antiparallel (By=0). For the By=0 case, a pair of slow shocks is formed as the result of evolution of the initial current sheet, and each slow shock consists of two parts: the isothermal main shock and the foreshock. In the present paper, cases with By≠0 are also considered, in which the evolution process leads to the presence of an additional pair of time-dependent intermediate shocks (TDISs). Across the main shock of the slow shock, jumps in plasma density, velocity, and magnetic field are significant, but the temperature is continuous. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. In contrast to the earlier study, the foreshock is found to reach a steady state with a constant width in the slow shock frame. In cases with By≠0, the plasma density and pressure increase and the magnetic field decreases across TDIS. The TDIS initially can be embedded in the slow shock’s foreshock structure, and then moves out of the foreshock region. With an increasing By, the propagation speed of foreshock leading edge tends to decrease and the foreshock reaches its steady state at an earlier time. Both the pressure and temperature downstreams of the main shock decrease with increasing By. The results can be applied to the shock heating in the solar corona and solar wind.
Finite rank Butler groups and torsion-free modules over a discrete valuation ring
Authors: Arnold D. , Dugas M. , Rangaswamy K.
Published: July 2005

Fully faithful functors from isomorphism at

p
p

categories of finite rank Butler groups to torsion-free modules of finite rank over the integers localized at a prime

p
p

are constructed via categories of representations of antichains over discrete valuation rings. Descriptions and properties of modules in the images of these functors are given, including a characterization of finite representation type and a complete list of indecomposables in that case.
The size of the Dini subdifferential
Authors: Benoist Joël
Published: July 2005

Given a lower semicontinuous function

f
:

R

h

→

R

∪
{
+
∞
}

f:\mathbb {R}^h \rightarrow \mathbb {R} \cup \{+\infty \}

, we prove that the points of

R

h

\mathbb {R}^h

, where the lower Dini subdifferential contains more than one element, lie in a countable union of sets which are isomorphic to graphs of some Lipschitzian functions defined on

R

h
−
1

\mathbb {R}^{h-1}

. Consequently, the set of all these points has a null Lebesgue measure.
On the dimension of a homeomorphism group
Authors: Brechner Beverly , Kawamura Kazuhiro
Published: July 2005

We prove that the homeomorphism group of each one of a collection of continua constructed in a paper by the first author (Trans. Amer. Math. Soc. 121 (1966), 516–548) is one dimensional. This answers a question posed in that paper.
Absolutely continuous measures on non quasi-analytic curves with independent powers
Authors: Olofsson Mats
Published: July 2005

We prove that every non quasi-analytic Carleman class contains functions whose graph supports measures that are absolutely continuous with respect to arc length measure and yet they have independent convolution powers in the measure algebra

M
(

R

2

)

M(\mathbb {R}^2)

. The proof relies on conditions which ensure that the canonical map between two Cantor sets can be extended to a function in an arbitrary prescribed non quasi-analytic Carleman class.
No 𝑛-point set is 𝜎-compact
Authors: Bouhjar Khalid , Dijkstra Jan , Mauldin R.
Published: July 2005

Let

n
n

be an integer greater than 1. We prove that there exist no

F
σ

F_\sigma

-subsets of the plane that intersect every line in precisely

n
n

points.
Global existence for the critical generalized KdV equation
Authors: Fonseca G. , Linares F. , Ponce G.
Published: July 2005

We discuss results regarding global existence of solutions for the critical generalized Korteweg-de Vries equation,
\[

u
t

+

u

x
x
x

+

u
4

u
x

=
0
,

x
,

t
∈

R

.

u_t+u_{xxx}+u^4\,u_x=0,\quad x,\,t\in \mathbb {R}.

\]
The theory established shows the existence of global solutions in Sobolev spaces with order below the one given by the energy space

H
1

(

R

)

H^1(\mathbb {R})

, i.e. solutions corresponding to data

u
0

∈

H
s

(

R

)

u_0\in H^s(\mathbb {R})

,

s
>
3

/

4

s>3/4

, with

‖

u
0

‖

L
2

>
‖
Q

‖

L
2

\|u_0\|_{L^2}>\|Q\|_{L^2}

, where

Q
Q

is the solitary wave solution of the equation.
Two-parameter spectral averaging and localization for non-monotonic random Schrödinger operators
Authors: Buschmann Dirk , Stolz Günter
Published: July 2005

We prove exponential localization at all energies for two types of one-dimensional random Schrödinger operators: the Poisson model and the random displacement model. As opposed to Anderson-type models, these operators are not monotonic in the random parameters. Therefore the classical one-parameter version of spectral averaging, as used in localization proofs for Anderson models, breaks down. We use the new method of two-parameter spectral averaging and apply it to the Poisson as well as the displacement case. In addition, we apply results from inverse spectral theory, which show that two-parameter spectral averaging works for sufficiently many energies (all but a discrete set) to conclude localization at all energies.
Strichartz estimates in the hyperbolic space and global existence for the semilinear wave equation
Authors: Tataru Daniel
Published: July 2005

The aim of this article is twofold. First we consider the wave equation in the hyperbolic space

H

n

\mathbb H^n

and obtain the counterparts of the Strichartz type estimates in this context. Next we examine the relationship between semilinear hyperbolic equations in the Minkowski space and in the hyperbolic space. This leads to a simple proof of the recent result of Georgiev, Lindblad and Sogge on global existence for solutions to semilinear hyperbolic problems with small data. Shifting the space-time Strichartz estimates from the hyperbolic space to the Minkowski space yields weighted Strichartz estimates in

R

n

×

R

\mathbb R^{n} \times \mathbb R

which extend the ones of Georgiev, Lindblad, and Sogge.
Correction to “Optimal factorization of Muckenhoupt weights”
Authors: Korey Michael
Published: July 2005

Peter Jones’ theorem on the factorization of

A
p

A_p

 weights is sharpened for weights with bounds near 

1
1

, allowing the factorization to be performed continuously near the limiting, unweighted case. When

1
>
p
>
∞

1>p>\infty

and

w
w

is an

A
p

A_p

 weight with bound

A
p

(
w
)
=
1
+
ε

A_p(w)=1+\varepsilon

, it is shown that there exist

A
1

A_1

 weights 

u
,
v

u,v

such that both the formula

w
=
u

v

1
−
p

w=uv^{1-p}

and the estimates

A
1

(
u
)
,

A
1

(
v
)
=
1
+

O

(

ε

)

A_1(u), A_1(v)=1+\mathcal O(\sqrt \varepsilon )

hold. The square root in these estimates is also proven to be the correct asymptotic power as

ε
→
0

\varepsilon \to 0

.
Axiom A flows with a transverse torus
Authors: Morales C.
Published: July 2005

Let

X
X

be an Axiom A flow with a transverse torus

T
T

exhibiting a unique orbit

O
O

that does not intersect

T
T

. Suppose that there is no null-homotopic closed curve in

T
T

contained in either the stable or unstable set of

O
O

. Then we show that

X
X

has either an attracting periodic orbit or a repelling periodic orbit or is transitive. In particular, an Anosov flow with a transverse torus is transitive if it has a unique periodic orbit that does not intersect the torus.
Hyperplane arrangements and linear strands in resolutions
Authors: Peeva Irena
Published: July 2005

The cohomology ring of the complement of a central complex hyperplane arrangement is the well-studied Orlik-Solomon algebra. The homotopy group of the complement is interesting, complicated, and few results are known about it. We study the ranks for the lower central series of such a homotopy group via the linear strand of the minimal free resolution of the field

C

\mathbf {C}

over the Orlik-Solomon algebra.
Linear systems of plane curves with a composite number of base points of equal multiplicity
Authors: Buckley Anita , Zompatori Marina
Published: July 2005

In this article we study linear systems of plane curves of degree

d
d

passing through general base points with the same multiplicity at each of them. These systems are known as homogeneous linear systems. We especially investigate for which of these systems, the base points, with their multiplicities, impose independent conditions and which homogeneous systems are empty. Such systems are called non-special. We extend the range of homogeneous linear systems that are known to be non-special. A theorem of Evain states that the systems of curves of degree

d
d

with

4
h

4^h

base points with equal multiplicity are non-special. The analogous result for

9
h

9^h

points was conjectured. Both of these will follow, as corollaries, from the main theorem proved in this paper. Also, the case of

4

h

9

k

4^{h}9^{k}

points will follow from our result. The proof uses a degeneration technique developed by C. Ciliberto and R. Miranda.
Tamagawa numbers of diagonal cubic surfaces, numerical evidence
Authors: Peyre Emmanuel , Tschinkel Yuri
Published: July 2005

A refined version of Manin’s conjecture about the asymptotics of points of bounded height on Fano varieties has been developed by Batyrev and the authors. We test numerically this refined conjecture for some diagonal cubic surfaces.
Securin and Separase Phosphorylation Act Redundantly to Maintain Sister Chromatid Cohesion in Mammalian Cells
Authors: Huang Xingxu , Hatcher Rashieda , York J. Philippe , Zhang Pumin
Published: July 2005

The spindle assembly checkpoint monitors the integrity of the spindle microtubules, which attach to sister chromatids at kinetochores and play a vital role in preserving genome stability by preventing missegregation. A key target of the spindle assembly checkpoint is securin, the separase inhibitor. In budding yeast, loss of securin results in precocious sister chromatid separation when the microtubule spindle is disrupted. However, in contrast to budding yeast, mammalian securin is not required for spindle checkpoint, suggesting that there are redundant mechanisms controlling the dissolution of sister chromatid cohesion in the absence of securin. One candidate mechanism is the inhibitory phosphorylation of separase. We generated a nonphosphorylable point mutant (S1121A) separase allele in securin-/- mouse embryonic stem cells. Securin-/-separase+/S1121A cells are viable but fail to maintain sister chromatid cohesion in response to the disruption of spindle microtubules, show enhanced sensitivity to nocodazole, and cannot recover from prometaphase arrest.
Cyclicity in the fossil record mirrors rock outcrop area
Authors: Smith Andrew B , McGowan Alistair J
Published: July 2005

In a recent article, Rohde & Muller (Rohde & Muller 2005
Nature
434
, 208–210) identified a strong 62 Myr cyclicity in the history of marine diversity through the Phanerozoic. The data they presented were highly convincing, yet they were unable to explain what process might have generated this pattern. A significant correlation between observed genus-level diversity (after removal of long-term trends) and the amount of marine sedimentary rock measured at a surface outcrop in Western Europe is demonstrated. This suggests that cyclicity originates from long-term changes in sedimentary depositional and erosional regimes, and raises the strong possibility that the cyclicity apparent in the record of marine fossils is not a biological signal but a sampling signal.
Problems with mitochondrial DNA as a marker in population, phylogeographic and phylogenetic studies: the effects of inherited symbionts
Authors: Hurst Gregory D.D , Jiggins Francis M
Published: July 2005

Mitochondrial DNA (mtDNA) has been a marker of choice for reconstructing historical patterns of population demography, admixture, biogeography and speciation. However, it has recently been suggested that the pervasive nature of direct and indirect selection on this molecule renders any conclusion derived from it ambiguous. We review here the evidence for indirect selection on mtDNA in arthropods arising from linkage disequilibrium with maternally inherited symbionts. We note first that these symbionts are very common in arthropods and then review studies that reveal the extent to which they shape mtDNA evolution. mtDNA diversity patterns are compatible with neutral expectations for an uninfected population in only 2 of 19 cases. The remaining 17 studies revealed cases of symbiont-driven reduction in mtDNA diversity, symbiont-driven increases in diversity, symbiont-driven changes in mtDNA variation over space and symbiont-associated paraphyly of mtDNA. We therefore conclude that these elements often confound the inference of an organism's evolutionary history from mtDNA data and that mtDNA on its own is an unsuitable marker for the study of recent historical events in arthropods. We also discuss the impact of these studies on the current programme of taxonomy based on DNA bar-coding.
The hydrophobic segment of Potato virus X TGBp3 is a major determinant of the protein intracellular trafficking
Authors: Schepetilnikov M. V. , Manske U. , Solovyev A. G. , Zamyatnin A. A. , Schiemann J. , Morozov S. Yu.
Published: July 2005

Potato virus X(PVX) encodes three movement proteins, TGBp1, TGBp2 and TGBp3. The 8 kDa TGBp3 is a membrane-embedded protein that has an N-terminal hydrophobic sequence segment and a hydrophilic C terminus. TGBp3 mutants with deletions in the C-terminal hydrophilic region retain the ability to be targeted to cell peripheral structures and to support limited PVX cell-to-cell movement, suggesting that the basic TGBp3 functions are associated with its N-terminal transmembrane region. Fusion of green fluorescent protein to the TGBp3 N terminus abrogates protein activities in intracellular trafficking and virus movement. The intracellular transport of TGBp3 from sites of its synthesis in the rough endoplasmic reticulum (ER) to ER-derived peripheral bodies involves a non-conventional COPII-independent pathway. However, integrity of the C-terminal hydrophilic sequence is required for entrance to this non-canonical route.
Vesicular stomatitis virus pseudotyped with severe acute respiratory syndrome coronavirus spike protein
Authors: Fukushi Shuetsu , Mizutani Tetsuya , Saijo Masayuki , Matsuyama Shutoku , Miyajima Naoko , Taguchi Fumihiro , Itamura Shigeyuki , Kurane Ichiro , Morikawa Shigeru
Published: July 2005

Severe acute respiratory syndrome coronavirus (SARS-CoV) contains a single spike (S) protein, which binds to its receptor, angiotensin-converting enzyme 2 (ACE2), induces membrane fusion and serves as a neutralizing antigen. A SARS-CoV-S protein-bearing vesicular stomatitis virus (VSV) pseudotype using the VSVΔG* system was generated. Partial deletion of the SARS-CoV-S protein cytoplasmic domain allowed efficient incorporation into VSV particles and led to the generation of a pseudotype (VSV-SARS-St19) at high titre. Green fluorescent protein expression was demonstrated as early as 7 h after infection of Vero E6 cells with VSV-SARS-St19. VSV-SARS-St19 was neutralized by anti-SARS-CoV antibody and soluble ACE2, and its infection was blocked by treatment of Vero E6 cells with anti-ACE2 antibody. These results indicated that VSV-SARS-St19 infection is mediated by SARS-CoV-S protein in an ACE2-dependent manner. VSV-SARS-St19 will be useful for analysing the function of SARS-CoV-S protein and for developing rapid methods of detecting neutralizing antibodies specific for SARS-CoV infection.
Structures of plant viruses from vibrational circular dichroism
Authors: Shanmugam Ganesh , Polavarapu Prasad L. , Kendall Amy , Stubbs Gerald
Published: July 2005

Vibrational circular dichroism (VCD) spectra in the amide I and II regions have been measured for viruses for the first time. VCD spectra were recorded for films prepared from aqueous buffer solutions and also for solutions using D2O buffers at pH 8. Investigations of four filamentous plant viruses, Tobacco mosaic virus (TMV), Papaya mosaic virus, Narcissus mosaic virus (NMV) and Potato virus X (PVX), as well as a deletion mutant of PVX, are described in this paper. The film VCD spectra of the viruses clearly revealed helical structures in the virus coat proteins; the nucleic acid bases present in the single-stranded RNA could also be characterized. In contrast, the solution VCD spectra showed the characteristic VCD bands for α-helical structures in the coat proteins but not for RNA. Both sets of results clearly indicated that the coat protein conformations are dominated by helical structures, in agreement with earlier reports. VCD results also indicated that the coat protein structures in PVX and NMV are similar to each other and somewhat different from that of TMV. The present study demonstrates the feasibility of measuring VCD spectra for viruses and extracting structural information from these spectra.
Poor taxon sampling, poor character sampling, and non‐repeatable analyses of a contrived dataset do not provide a more credible estimate of insect phylogeny: a reply to Kjer
Authors: Ogden T. Heath , Whiting Michael F. , Wheeler Ward C.
Published: July 2005

The wealth of data available for phylogenetic analysis of the insect orders, from both morphological and molecular sources, is steadily increasing. However, controversy exists among the methodologies one can use to reconstruct ordinal relationships. Recently, Kjer (2004) presented an analysis of insect ordinal relationships based exclusively on a single source of information: 18S rDNA sequence data. Kjer claims that his analysis resulted in a more “credible” phylogeny for the insect orders and strongly criticized our previous phylogenetic results. However, Kjer only used a subset of the data that are currently available for insect ordinal phylogeny, misrepresented our analyses, and omitted other analyses we have published on insect ordinal phylogeny. In our estimation, Kjer did a poor job of representing the current state of affairs in insect ordinal phylogenetics. Furthermore, we examine a number of analytical issues that are relevant not only for insect phylogeny, but systematics as a science, such as: repeatability and objectivity, locating alignment boundaries, secondary structure, goodness of fit measure, epistemological coherence, practicality and homology.

© The Willi Hennig Society 2005.
Thermodynamic Calculation of the ZrO2–YO1.5–MgO System
Authors: Du Yong , Jin Zhanpeng , Huang Peiyun
Published: July 2005

A thermodynamic evaluation of the ZrO2‐MgO system has been developed and combined with previous assessments of the ZrO2–YO1.5 and YO1.5–MgO systems to describe the ZrO2–YO1.5‐MgO Systems to describe the ZrO2–YO1.5‐MgO system by means of Bonnier's equation. The calculated results are shown by isothermal and vertical sections, a projection of the liquidus surfaces, and the reaction scheme. Comparisons between calculated and experimental diagrams demonstrate that the calculations satisfactorily account for most of the available experimental data.
Journal. Matrix‐Grain‐Bridging Contributions to the Toughness of Whisker‐Reinforced Ceramics
Authors: Becher Paul F. , Fuller Edwin R. , Angelini Peter
Published: July 2005

The fracture toughness of whisker‐reinforced, noncubic ceramic matrices increases with increases in matrix grain size, d, as well as with increases in whisker content. An analytical description for the grain‐bridging toughening contribution is combined with the whisker‐bridging contribution to describe the toughness of such composites. Results for SiC‐whisker‐reinforced alumina composites confirm both the predicted grain‐size effect and the coupled toughening response in the presence of these two toughening mechanisms.
Thermal Residual Stresses in Ceramic‐to‐Metal Brazed Joints
Authors: Levy Alvin
Published: July 2005

When a ceramic‐to‐metal brazed joint is fabricated, residual stresses develop as the material is cooled from the brazing temperature to room temperature. These residual stresses reduce the strength of the brazed joint, and in some cases lead to catastrophic failure at or near an interface, during the brazing process itself. Finite element analysis modeling techniques are presented and used to determine the residual stresses inherent in the bonding process. Elastoplastic material behavior of the active filler metal, including its temperature‐dependent stress–strain response, is accounted for. Various combinations of ceramics and metals are considered. Residual stresses are calculated and used to explain joint strength. The effects of the filler metal work‐hardening rate and thickness on the levels of residual stresses are investigated. Analysis shows that the conclusions reached from a laboratory‐brazed coupon test may not be applicable to the practical case in which ceramic tiles are brazed onto a metal substrate. There is qualitative agreement between analytical predictions and experimental findings regarding failure modes that occur during cooling from the brazing temperature to room temperature.
Corrosion Kinetics and Strength Degradation of Sintered δ‐Silicon Carbide in Potassium Sulfate Melts
Authors: Sato Tsugio , Kubota Kazuhide , Shimada Masahiko
Published: July 2005

Pressureless sintered α‐SiC ceramics containing carbon and boron as sintering aids and hot‐pressed SiC containing aluminum nitride as a sintering aid were corroded in K2SO4 melts at 1080° to 1150°C. SiC ceramics were oxidized and dissolved into K2SO4 melts. Since the corrosion of SiC ceramics in K2SO4 melts proceeded autocatalytically, a reaction product such as K2S1.44 was suspected to promote the corrosion reaction. The corrosion resistance of SiC containing AlN in K2SO4 melt was superior to that of SiC containing boron and carbon. Apparent activation energies for the corrosion of SiC ceramics were 309 to 331 kJ mol‐1. The fracture strength of the specimens corroded by K2SO4 melt degraded to 40% to 70% of the original values up to a 20% weight loss and then was almost constant up to 45% weight loss.