bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing long‐term fire risk at local scale by means of decision tree technique
Authors: Amatulli Giuseppe , Rodrigues Maria João , Trombetti Marco , Lovreglio Raffaella
Published: August 2006

The main problem encountered when applying remote sensing and geographic information systems techniques for wildfire risk assessment is the necessity to integrate different data sources. The methods applied so far are usually based on regression techniques or on coefficients relying on experts' knowledge. Hence fire managers are seeking an unbiased statistical model able to highlight the multivariate spatial relationships between the predictor variables, yielding understandable output readily accessible to end users. The present research aims to test the capability of classification and regression trees (CART) analysis to assess long‐term fire risk at a local scale. The CART analysis is a nonparametric statistical technique which generates decision rules in the form of a binary tree, for a classification or a regression process. A fire‐prone study area was selected in the southeast of Italy. Fire ignition points, relative to a 7 year period (1997–2003), were used to derive a fire occurrence map through a kernel density approach. The resulting map was then used as input response variable for the CART analysis with fire danger variables used as predictors. The rules induced by the regression process allowed the definition of different risk levels, expressed as 30 management units, which is useful for producing a fire risk map. The result of the regression process (r= 0.77), the capability of the CART analysis to highlight the hierarchical relationships among the predictor variables, and the improved interpretability of the regression rules represent a possible tool useful for better approaching the problem of assessing and representing fire risk.
Shear wave speed structure beneath the South Pacific superswell using broadband data from ocean floor and islands
Authors: Isse Takehi , Suetsugu Daisuke , Shiobara Hajime , Sugioka Hiroko , Yoshizawa Kazunori , Kanazawa Toshihiko , Fukao Yoshio
Published: August 2006

We determined three‐dimensional shear wave speed structure beneath the South Pacific superswell down to a depth of 200 km by analyzing Rayleigh wave records from broadband ocean bottom seismograph stations and island stations in the Pacific Ocean. The ocean bottom stations were deployed from 2003 to 2005 on the seafloor in the French Polynesian region, which enabled us to study the upper mantle structure beneath the Superswell with unprecedentedly high resolution. We measured the dispersions of fundamental mode Rayleigh waves at periods between 40 and 140 seconds by the two‐station method. We found pronounced slow anomalies near the hot spots and in the Lau Basin. The slow anomalies beneath the hot spots have deeper‐rooted than those associated with the Lau basin. The slow anomalies near the Society, Macdonald, Marquesas, and Pitcairn hot spots continue down to at least 200 km depth.
Trophic effect of angiotensin II in neonatal rat cardiomyocytes: role of endothelin‐1 and non‐myocyte cells
Authors: Pönicke Klaus , Heinroth‐Hoffmann Ingrid , Becker Karin , Brodde Otto‐Erich
Published: August 2006

Angiotensin II (AII) and the endothelins (ET) are known to be potent trophic stimuli in various cells including cardiomyocytes. In order to characterize further these effects we studied, in neonatal rat ventricular cardiomyocytes, the effects of several endothelin‐receptor antagonists and the AT1‐receptor antagonist losartan on AII‐ and endothelin‐induced inositol phosphate (IP)‐formation (assessed as accumulation of total [3H]‐IPs in myo‐[3H]‐inositol prelabelled cells) and increase in rate of protein synthesis (assessed as [3H]‐phenylalanine incorporation).

Endothelin (10 pM–1 μM) concentration‐dependently increased IP‐formation (max. increase at 100 nM ET‐1: 130±14% above basal, n=25) and [3H]‐phenylalanine incorporation (max. increase at 1 μM: 52±4% above basal, n=16) with an order of potency: ET‐1>>ET‐3. Both effects were antagonized by the ETA/ETB‐receptor antagonist bosentan and the ETA‐receptor antagonist BQ‐123, but not affected by the ETB‐receptor antagonist IRL 1038 and the AT1‐receptor antagonist losartan.

Pretreatment of the cells with 500 ng ml−1 pertussis toxin (PTX) overnight that completely inactivated PTX‐sensitive G‐proteins did not attenuate but rather enhance ET‐1‐induced IP‐formation. On the other hand, in PTX‐pretreated cardiomyocytes ET‐1‐induced [3H]‐phenylalanine incorporation was decreased by 39±5% (n=5).

AII (1 nM–1 μM) concentration‐dependently increased IP‐formation (max. increase at 1 μM: 42±7% above basal, n=16) and [3H]‐phenylalanine incorporation (max. increase at 1 μM: 29±2%, n=9). These effects were antagonized by losartan, but they were also antagonized by bosentan and BQ‐123.

In well‐defined cultures of cardiomyocytes (not contaminated with non‐myocyte cells) AII failed to increase [3H]‐phenylalanine incorporation; addition of non‐myocyte cells to the cardiomyocytes restored AII‐induced increase in [3H]‐phenylalanine incorporation.

We conclude that, in rat neonatal ventricular cardiomyocytes, (a) the ET‐1‐induced increase in rate of protein synthesis (through ETA‐receptor stimulation) involves at least two signalling pathways: one via a PTX‐insensitive G‐protein coupled to IP‐formation, and the other one via a PTX‐sensitive G‐protein, and (b) the trophic effects of AII are brought about via local ET‐1 secretion upon AT1‐receptor stimulation in neonatal rat ventricular non‐myocyte cells.

British Journal of Pharmacology (1997) 121, 118–124; doi:10.1038/sj.bjp.0701084
Down‐regulation of aortic and cardiac AT1 receptor gene expression in transgenic (mRen‐2) 27 rats
Authors: Nickenig G , Laufs U , Schnabel P , Knorr A , Paul M , Böhm M
Published: August 2006

Transgenic(TG) (mRen‐2) rats overexpressing the mouse renin gene develop fulminant hypertension and cardiac hypertrophy. Since the activation of AT1 receptor by angiotensin II is involved in blood pressure regulation, cardiac performance and myocardial growth, we investigated the biological effects of angiotensin II and the regulation of the AT1 receptor in the heart and aorta of TGR (mRen‐2)27 rats in comparison to control animals.

Contraction studies on isolated cardiac muscle strips reveal that angiotensin II exerts no positive inotropic effect on the left ventricular myocardium of both, transgenic and control rats. In contrast, angiotensin II leads via AT1 receptor activation in the left atrium of control rats to a significant contraction (130±5% of basal contraction) which is not detectable in left atrium preparations of the transgenic animals. Furthermore, AT1 receptor activation causes a profound contraction of aortic rings isolated from control rats amounting to 1.39±0.2 mN mg−1 wet weight, whereas aortic rings from TGR (mRen‐2)27 rats contract only minimally upon angiotensin II stimulation (0.2±0.02 mN mg−1 wet weight).

These altered physiological responses of angiotensin II in the transgenic rats are in part due to a marked down‐regulation of the AT1 receptor in atrial, ventricular and aortic tissue of these transgenic animals in comparison to control Sprague‐Dawley rats, as shown by radioligand binding assays and quantitative polymerase chain reaction (PCR) experiments. The AT1 receptor density Bmax in the left atrium was 1.3±0.08 fmol mg−1 protein in control rats (KD 1.1±0.18 nmol l−1) and 0.94±0.15 fmol mg−1 protein (KD 2.1±0.3 nmol l−1. In the aorta Bmax values were 15.1±0.5 fmol mg−1 protein (KD 1.9±0.27 nmol l−1) for control rats and 11.3±0.76 fmol mg−1 protein (KD 1.9±0.27 nmol l−1) for the TGR(mRen‐2)27 rats AT1 receptor mRNA was reduced in the transgenic animals to 46±3% in the left atrium, 50±11% in the left ventricle and 40±3% in the aorta, respectively.

Together, the AT1 receptor is down‐regulated in TGR (mRen‐2)27 rats in comparison to wildtype Sprague Dawley rats leading to a profoundly decreased response of cardiac and aortic tissue upon stimulation with angiotensin II.

British Journal of Pharmacology (1997) 121, 134–140; doi:10.1038/sj.bjp.0701088
Purine and pyrimidine nucleotide receptors in the apical membranes of equine cultured epithelia
Authors: Ko W H , Wilson S M , Wong P Y D
Published: August 2006

The short circuit current (ISC) technique was used to quantify electrolyte transport by equine cultured sweat gland epithelia. Adenosine 5′‐triphosphate (ATP) and certain related compounds, caused transient increases in ISC when added to the apical solution. The order of potency was uridine triphosphate (UTP)>ATP>ADP>>AMP=adenosine.

The responses to apical nucleotides were due to chloride and bicarbonate secretion and were reduced in pertussis toxin‐treated cells. P2‐receptors sensitive to uridine 5′‐triphosphate (UTP), that interact with inhibitory G proteins, therefore appear to be present in the apical membrane.

Responses to ATP and UTP were reduced in cells loaded with BAPTA, a calcium chelator. BAPTA attenuated the response to ATP more than the response to UTP suggesting that these nucleotides may not act via a common pathway.

Cross‐desensitization experiments indicated that two populations of UTP‐sensitive receptor were present. One was sensitive to UTP and ATP, whereas the second was sensitive only to UTP. Uridine diphosphate appeared to activate the ATP‐insensitive receptor population selectively.

These data suggest that apical pyrimidinoceptors may be expressed by these cells. The physiological role of these receptors is unknown but they may allow the autocrine regulation of epithelial function.

British Journal of Pharmacology (1997) 121, 150–156; doi:10.1038/sj.bjp.0701093
Characterization of the prostanoid receptors mediating inhibition of PAF‐induced aggregation of guinea‐pig eosinophils
Authors: Teixeira Mauro M , Al‐Rashed Sabah , Rossi Adriano G , Hellewell Paul G
Published: August 2006

Prostanoids induce a wide range of biological actions which are mediated by specific membrane‐bound receptors. We have recently shown that the E‐type prostaglandins, PGE1 and PGE2, effectively inhibit eosinophil aggregation induced by platelet‐activating factor (PAF). In an attempt to determine which prostanoid receptor(s) were involved, we investigated the effects of a range of selective prostanoid agonists and antagonists on eosinophil homotypic aggregation induced by PAF.

Both PGE1 and PGE2 (10−10 to 10−6 M) induced a concentration‐related inhibition of the aggregation response induced by PAF. PGE1 was more effective than PGE2 but PGE2 was slightly more potent than PGE1 (approximate IC50 values for PGE1 and PGE2 of 1.5×10−8 M and 5×10−9 M, respectively).

The EP2‐selective agonists, 11‐deoxy‐PGE1, butaprost and AH13205, and the EP2/EP3‐selective agonist, misoprostol, also inhibited PAF‐induced aggregation. The rank order of potency for EP2‐selective agonists was 11‐deoxy‐PGE1 > misoprostol > butaprost = AH13205. The protein kinase A inhibitor, KT5720 (10−6 M), reversed the inhibitory effects of 11‐deoxy‐PGE1 (10−6 M) and AH13205 (10−5 M).

The EP1/EP3‐selective agonist, sulprostone, and the EP1‐selective agonist, 17‐phenyl‐ω‐trinor PGE2, had no significant inhibitory activity when tested at concentrations up to 10−6 M. The EP4‐receptor antagonist, AH23848B, had no effect on PAF‐induced aggregation and did affect the inhibitory activity of PGE1.

The IP‐selective agonist, cicaprost (up to 10−6 M), and the IP/EP1‐receptor agonist, iloprost (up to 10−5 M), had no significant effect on PAF‐induced eosinophil aggregation. However, iloprost significantly augmented the inhibitory effects of a maximally inhibitory concentration of PGE2.

PGD2 (10−5 M) had no effect on eosinophil aggregation and the inhibitory activity of PGE1 on PAF‐induced eosinophil aggregation was not altered by the DP‐selective receptor antagonist, BWA868C.

The results presented here suggest that the inhibition of PAF‐induced eosinophil aggregation by prostanoids is mediated by the occupation of EP2‐receptors. It is important to note that the effects of naturally occuring prostanoids, such as PGE2, on eosinophil aggregation occur at low concentrations highlighting a potential role for EP2 receptors in regulating eosinophil function in vivo.

British Journal of Pharmacology (1997) 121, 77–82; doi:10.1038/sj.bjp.0701107
Alteration of flow‐induced dilatation in mesenteric resistance arteries of L‐NAME treated rats and its partial association with induction of cyclo‐oxygenase‐2
Authors: Henrion Daniel , Dechaux Elsa , Dowell Fiona J , Maclour Jacques , Samuel Jane‐Lise , Lévy Bernard I , Michel Jean‐Baptiste
Published: August 2006

We investigated the response to pressure (myogenic tone) and flow of rat mesenteric resistance arteries cannulated in an arteriograph which allowed the measurement of intraluminal diameter for controlled pressures and flows. Rats were treated for 3 weeks with NG‐nitro‐L‐arginine methyl ester (L‐NAME, 50 mg kg−1 day−1) or L‐NAME plus the angiotensin I converting enzyme inhibitor (ACEI) quinapril (10 mg kg−1 day−1).

Mean blood pressure increased significantly in chronic L‐NAME‐treated rats (155±4 mmHg, n=8, vs control 121±6 mmHg, n=10; P<0.05). L‐NAME‐treated rats excreted significantly more dinor‐6‐keto prostaglandin F1α (dinor‐6‐keto PGF1α), the stable urinary metabolite of prostacyclin, than control rats. The ACEI prevented the rise in blood pressure and the rise in urinary dinor‐6‐keto PGF1α due to L‐NAME.

Isolated mesenteric resistance arteries, developed myogenic tone in response to stepwise increases in pressure (42±6 to 847±10 mN mm−1, from 25 to 150 mmHg, n=9). Myogenic tone was not significantly affected by the chronic treatment with L‐NAME or L‐NAME+ACEI.

Flow (100 μl min−1) significantly attenuated myogenic tone by 50±6% at 150 mmHg (n=10). Flow‐induced dilatation was significantly attenuated by chronic L‐NAME to 22±6% at 150 mmHg (n=10, P=0.0001) and was not affected in the L‐NAME+ACEI group.

Acute in vitro NG‐nitro‐L‐arginine (L‐NOARG, 10 μM) significantly decreased flow‐induced dilatation in control but not in L‐NAME or L‐NAME+ACEI rats. Both acute indomethacin (10 μM) and acute NS 398 (cyclo‐oxygenase‐2 (COX‐2) inhibitor, 1 μM) did not change significantly flow‐induced dilatation in controls but they both decreased flow‐induced dilatation in the L‐NAME and L‐NAME+ACEI groups. Acute Hoe 140 (bradykinin receptor inhibitor, 1 μM) induced a significant contraction of the isolated mesenteric arteries which was the same in the 3 groups.

Immunofluorescence analysis of COX‐2 showed that the enzyme was expressed in resistance mesenteric arteries in L‐NAME and L‐NAME+ACEI groups but not in control. COX‐1 expression was identical in all 3 groups.

We conclude that chronic inhibition of nitric oxide synthesis is associated with a decreased flow‐induced dilatation in resistance mesenteric arteries which was compensated by an overproduction of vasodilator prostaglandins resulting in part from COX‐2 expression. The decrease in flow‐induced dilatation was prevented by the ACEI, quinapril.

British Journal of Pharmacology (1997) 121, 83–90; doi:10.1038/sj.bjp.0701109
Lsm proteins and RNA processing
Authors: Beggs J.D.
Published: August 2006

Sm and Lsm proteins are ubiquitous in eukaryotes and form complexes that interact with RNAs involved in almost every cellular process. My laboratory has studied the Lsm proteins in the yeast Saccharomyces cerevisiae, identifying in the nucleus and cytoplasm distinct complexes that affect pre-mRNA splicing and degradation, small nucleolar RNA, tRNA processing, rRNA processing and mRNA degradation. These activities suggest RNA chaperone-like roles for Lsm proteins, affecting RNA–RNA and/or RNA–protein interactions. This article reviews the properties of the Sm and Lsm proteins and structurally and functionally related proteins in archaea and eubacteria.
Reverse splicing of a mobile twin-ribozyme group I intron into the natural small subunit rRNA insertion site
Authors: Birgisdottir Å.B. , Johansen S.D.
Published: August 2006

A mobile group I intron containing two ribozyme domains and a homing endonuclease gene (twin-ribozyme intron organization) can integrate by reverse splicing into the small subunit rRNA of bacteria and yeast. The integration is sequence-specific and corresponds to the natural insertion site (homing site) of the intron. The reverse splicing is independent of the homing endonuclease gene, but is dependent on the group I splicing ribozyme domain. The observed distribution of group I introns in nature can be explained by horizontal transfer between natural homing sites by reverse splicing and subsequent spread in populations by endonuclease-dependent homing.
Ten remarks on peptide bond formation on the ribosome
Authors: Rodnina M.V. , Beringer M. , Bieling P.
Published: August 2006

Peptide-bond formation is the enzymatic activity of the ribosome. The catalytic site is made up of ribosomal RNA, indicating that the ribosome is a ribozyme. This review summarizes the recent progress in understanding the mechanism of peptide bond formation. The results of biochemical and kinetic experiments, mutagenesis studies and ribosome crystallography suggest that the approx. 107-fold rate enhancement of peptide bond formation by the ribosome is mainly due to substrate positioning within the active site, rather than to chemical catalysis.
A systems- and signal-oriented approach to intracellular dynamics
Authors: Wolkenhauer O. , Sreenath S.N. , Wellstead P. , Ullah M. , Cho K.-H.
Published: August 2006

A mathematical understanding of regulation, and, in particular, the role of feedback, has been central to the advance of the physical sciences and technology. In this article, the framework provided by systems biology is used to argue that the same can be true for molecular biology. In particular, and using basic modular methods of mathematical modelling which are standard in control theory, a set of dynamic models is developed for some illustrative cell signalling processes. These models, supported by recent experimental evidence, are used to argue that a control theoretical approach to the mechanisms of feedback in intracellular signalling is central to furthering our understanding of molecular communication. As a specific example, a MAPK (mitogen-activated protein kinase) signalling pathway is used to show how potential feedback mechanisms in the signalling process can be investigated in a simulated environment. Such ‘what if’ modelling/simulation studies have been an integral part of physical science research for many years. Using tools of control systems analysis, as embodied in the disciplines of systems biology, similar predictive modelling/simulation studies are now bearing fruit in cell signalling research.
Metabolomics, machine learning and modelling: towards an understanding of the language of cells
Authors: Kell D.B.
Published: August 2006

In answering the question ‘Systems Biology – will it work?’ (which it self-evidently has already), it is appropriate to highlight advances in philosophy, in new technique development and in novel findings. In terms of philosophy, we see that systems biology involves an iterative interplay between linked activities – for instance, between theory and experiment, between induction and deduction and between measurements of parameters and variables – with more emphasis than has perhaps been common now being focused on the first in each of these pairs. In technique development, we highlight closed loop machine learning and its use in the optimization of scientific instrumentation, and the ability to effect high-quality and quasi-continuous optical images of cells. This leads to many important and novel findings. In the first case, these may involve new biomarkers for disease, whereas in the second case, we have determined that many biological signals may be frequency-rather than amplitude-encoded. This leads to a very different view of how signalling ‘works’ (equations such as that of Michaelis and Menten which use only amplitudes, i.e. concentrations, are inadequate descriptors), lays emphasis on the signal processing network elements that lie ‘downstream’ of what are traditionally considered the signals, and allows one simply to understand how cross-talk may be avoided between pathways which nevertheless use common signalling elements. The language of cells is much richer than we had supposed, and we are now well placed to decode it.
The heart is already working
Authors: Noble D.
Published: August 2006

Understanding the logic of living systems requires knowledge of the mechanisms involved at the levels at which functionality is expressed. This information resides neither in the genome, nor even in the individual proteins that genes code for. No functionality is expressed at these levels. It emerges as the result of interactions between many proteins relating to each other in multiple cascades and in interaction with the cellular environment. There is therefore no alternative to copying nature and computing these interactions to determine the logic of healthy and diseased states. The rapid growth in biological databases, models of cells, tissues and organs and the development of powerful computing hardware and algorithms have made it possible to explore functionality in a quantitative manner all the way from the level of genes to the physiological function of whole organs and regulatory systems. I use models of the heart to demonstrate that we can now go all the way from individual genetic information (on mutations, for example) to exploring the consequences at a whole-organ level.
Two-dimensional electronic spectroscopy of the B800–B820 light-harvesting complex
Authors: Zigmantas Donatas , Read Elizabeth L. , Mančal Tomáš , Brixner Tobias , Gardiner Alastair T. , Cogdell Richard J. , Fleming Graham R.
Published: August 2006

Emerging nonlinear optical spectroscopies enable deeper insight into the intricate world of interactions and dynamics of complex molecular systems. 2D electronic spectroscopy appears to be especially well suited for studying multichromophoric complexes such as light-harvesting complexes of photosynthetic organisms as it allows direct observation of couplings between the pigments and charts dynamics of energy flow on a 2D frequency map. Here, we demonstrate that a single 2D experiment combined with self-consistent theoretical modeling can determine spectroscopic parameters dictating excitation energy dynamics in the bacterial B800–B820 light-harvesting complex, which contains 27 bacteriochlorophyll molecules. Ultrafast sub-50-fs dynamics dominated by coherent intraband processes and population transfer dynamics on a picosecond time scale were measured and modeled with one consistent set of parameters. Theoretical 2D spectra were calculated by using a Frenkel exciton model and modified Förster/Redfield theory for the calculation of dynamics. They match the main features of experimental spectra at all population times well, implying that the energy level structure and transition dipole strengths are modeled correctly in addition to the energy transfer dynamics of the system.
Nationalism, Masculinity and Multicultural Citizenship in Serbia*
Authors: Greenberg Jessica
Published: August 2006

Since the 5 October revolution that formally ushered Serbia into a democratic era, political commentators, scholars, civic activists and others have watched the country for signs of resurgent nationalism. Many perceived the primary threat to the new democratic order as the persistence of nationalism, particularly in the years after the 2003 assassination of Zoran Djindjić. Such nationalism, forged in the 1980s and 1990s, was subject to eruptions among unsavory politicians, pensioners, Mafiosi and denizens of Belgrade's suburbs and Serbia's “backward” countryside. The problem underlying this model of resurgent nationalism is that it assumes, and simultaneously constructs, nationalism as a static and unchanging arrangement of ideological and social factors that flare up and die down in response to political stimuli—the arrest of indicted war criminals, the outrageous rhetoric of populist politicians, negotiations over the status of Kosovo, or high-stakes sporting events. While there is no question that such events create discursive space for nationalist, sexist and racist agendas, the flare-up model presents a dangerous simplification of how nationalisms work.
Links in an open book decomposition and in the standard contact structure
Authors: Matsuda Hiroshi
Published: August 2006

We study a relationship between arc presentations of links in

R

3

\mathbb {R}^3

and Legendrian links in

R

3

\mathbb {R}^3

with the standard tight contact structure. We determine the arc indices of torus knots.
A short proof of a conjecture on the connectivity of graph coloring complexes
Authors: Engström Alexander
Published: August 2006

The

H
o
m

\mathtt {Hom}

–complexes were introduced by Lovász to study topological obstructions to graph colorings. It was conjectured by Babson and Kozlov, and proved by Čukić and Kozlov, that

H
o
m

(
G
,

K
n

)

\mathtt {Hom}(G,K_n)

is

(
n
−
d
−
2
)

(n-d-2)

–connected, where

d
d

is the maximal degree of a vertex of

G
G

, and

n
n

the number of colors. We give a short proof of the conjecture.
A Myers-type theorem and compact Ricci solitons
Authors: Derdzinski Andrzej
Published: August 2006

Let the Ricci curvature of a compact Riemannian manifold be greater, at every point, than the Lie derivative of the metric with respect to some fixed smooth vector field. It is shown that the fundamental group then has only finitely many conjugacy classes. This applies, in particular, to all compact shrinking Ricci solitons.
Almost automorphic solutions for semilinear boundary differential equations
Authors: Boulite S. , Maniar L. , N’Guérékata G.
Published: August 2006

In this work, we use the extrapolation methods to study the existence and uniqueness of almost automorphic solutions to the semilinear boundary differential equation
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout Enlarged left-brace 1st Row 1st Column x prime left-parenthesis t right-parenthesis 2nd Column a m p semicolon equals upper A Subscript m Baseline x left-parenthesis t right-parenthesis plus h left-parenthesis t comma x left-parenthesis t right-parenthesis right-parenthesis comma 3rd Column a m p semicolon 4th Column a m p semicolon t element-of double-struck upper R comma 2nd Row 1st Column upper L x left-parenthesis t right-parenthesis 2nd Column a m p semicolon equals g left-parenthesis t comma x left-parenthesis t right-parenthesis right-parenthesis comma 3rd Column a m p semicolon 4th Column a m p semicolon t element-of double-struck upper R comma EndLayout">

{

x
′

(
t
)

a
m
p
;
=

A
m

x
(
t
)
+
h
(
t
,
x
(
t
)
)
,

a
m
p
;

a
m
p
;
t
∈

R

,

L
x
(
t
)

a
m
p
;
=
g
(
t
,
x
(
t
)
)
,

a
m
p
;

a
m
p
;
t
∈

R

,

\begin{equation} \tag {SBDE} \left \{ \begin {aligned} x’(t) &= A_mx(t)+h(t,x(t)), && t\in \mathbb {R}, \\ Lx(t) &= g(t,x(t)), && t\in \mathbb {R}, \end{aligned} \right . \end{equation}

where

A
:=

A
m

|

ker
⁡
L

A:=A_m|\ker L

generates a hyperbolic

C
0

C_0

-semigroup on a Banach space

X
X

and

h
,
g

h,g

are almost automorphic functions which take values in

X
X

and a “boundary space”

∂
X

\partial X

, respectively. These equations are an abstract formulation of partial differential equations with semilinear terms at the boundary, such as population equations, retarded differential equations and boundary control systems. An application to retarded differential equations is given.
Almost simple groups of Suzuki type acting on polytopes
Authors: Leemans Dimitri
Published: August 2006

Let

S
=
S
z
(
q
)

S = Sz(q)

, with

q
≠
2

q\neq 2

an odd power of two. For each almost simple group

G
G

such that

S
>
G
≤
A
u
t
(
S
)

S > G \leq Aut(S)

, we prove that

G
G

is not a C-group and therefore is not the automorphism group of an abstract regular polytope. For

G
=
S
z
(
q
)

G = Sz(q)

, we show that there is always at least one abstract regular polytope

P

\mathcal {P}

such that

G
=
A
u
t
(

P

)

G = Aut(\mathcal {P})

. Moreover, if

P

\mathcal {P}

is an abstract regular polytope such that

G
=
A
u
t
(

P

)

G = Aut(\mathcal {P})

, then

P

\mathcal {P}

is a polyhedron.
On the minimum of several random variables
Authors: Gordon Y. , Litvak A. , Schütt C. , Werner E.
Published: August 2006

For a given sequence of real numbers

a

1

,
…
,

a

n

a_{1}, \dots , a_{n}

, we denote the

k
k

th smallest one by

k

-

min

1
≤
i
≤
n

a

i

{k\mbox {-}\min } _{1\leq i\leq n}a_{i}

. Let

A

\mathcal {A}

be a class of random variables satisfying certain distribution conditions (the class contains

N
(
0
,
1
)

N(0, 1)

Gaussian random variables). We show that there exist two absolute positive constants

c
c

and

C
C

such that for every sequence of real numbers

0
>

x

1

≤
…
≤

x

n

0> x_{1}\leq \ldots \leq x_{n}

and every

k
≤
n

k\leq n

, one has
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="c max Underscript 1 less-than-or-equal-to j less-than-or-equal-to k Endscripts StartFraction k plus 1 minus j Over sigma-summation Underscript i equals j Overscript n Endscripts 1 slash x Subscript i Baseline EndFraction less-than-or-equal-to double-struck upper E k hyphen min Underscript 1 less-than-or-equal-to i less-than-or-equal-to n Endscripts StartAbsoluteValue x Subscript i Baseline xi Subscript i Baseline EndAbsoluteValue less-than-or-equal-to upper C ln left-parenthesis k plus 1 right-parenthesis max Underscript 1 less-than-or-equal-to j less-than-or-equal-to k Endscripts StartFraction k plus 1 minus j Over sigma-summation Underscript i equals j Overscript n Endscripts 1 slash x Subscript i Baseline EndFraction comma">

c

max

1
≤
j
≤
k

 

k
+
1
−
j

∑

i
=
j

n

1

/

x
i

≤

E

k

-

min

1
≤
i
≤
n

|

x

i

ξ

i

|

≤
C

ln
⁡
(
k
+
1
)

max

1
≤
j
≤
k

 

k
+
1
−
j

∑

i
=
j

n

1

/

x
i

,

c \max _{1 \leq j \leq k}\ \frac {k+1-j}{\sum _{i=j}^n 1/x_i } \leq \mathbb E \, \, k\mbox {-}\min _{1\leq i\leq n} |x_{i} \xi _{i}| \leq C\, \ln (k+1)\, \max _{1 \leq j \leq k}\ \frac {k+1-j}{\sum _{i=j}^n 1/x_i},

\]
where

ξ
1

,
…
,

ξ
n

\xi _1, \dots , \xi _n

are independent random variables from the class

A

\mathcal {A}

. Moreover, if

k
=
1

k=1

, then the left-hand side estimate does not require independence of the

ξ
i

\xi _i

’s. We provide similar estimates for the moments of

k

-

min

1
≤
i
≤
n

|

x

i

ξ

i

|

{k\mbox {-}\min }_{1\leq i\leq n} |x_{i} \xi _{i}|

as well.
Conformal mapping and ellipses
Authors: Ledet Arne , Solynin Alexander
Published: August 2006

We answer a question raised by M. Chuaqui, P. Duren, and B. Osgood by showing that a conformal mapping of a simply connected domain cannot take two circles onto two proper ellipses.
A lower bound for the ground state energy of a Schrödinger operator on a loop
Authors: Linde Helmut
Published: August 2006

Consider a one-dimensional quantum mechanical particle described by the Schrödinger equation on a closed curve of length

2
π

2\pi

. Assume that the potential is given by the square of the curve’s curvature. We show that in this case the energy of the particle cannot be lower than

0.6085
0.6085

. We also prove that it is not lower than

1
1

(the conjectured optimal lower bound) for a certain class of closed curves that have an additional geometrical property.
Orthogonal polynomials for refinable linear functionals
Authors: Laurie Dirk , de Villiers Johan
Published: August 2006

A refinable linear functional is one that can be expressed as a convex combination and defined by a finite number of mask coefficients of certain stretched and shifted replicas of itself. The notion generalizes an integral weighted by a refinable function. The key to calculating a Gaussian quadrature formula for such a functional is to find the three-term recursion coefficients for the polynomials orthogonal with respect to that functional. We show how to obtain the recursion coefficients by using only the mask coefficients, and without the aid of modified moments. Our result implies the existence of the corresponding refinable functional whenever the mask coefficients are nonnegative, even when the same mask does not define a refinable function. The algorithm requires

O
(

n
2

)

O(n^2)

rational operations and, thus, can in principle deliver exact results. Numerical evidence suggests that it is also effective in floating-point arithmetic.
Elliptic reconstruction and a posteriori error estimates for fully discrete linear parabolic problems
Authors: Lakkis Omar , Makridakis Charalambos
Published: August 2006

We derive a posteriori error estimates for fully discrete approximations to solutions of linear parabolic equations. The space discretization uses finite element spaces that are allowed to change in time. Our main tool is an appropriate adaptation of the elliptic reconstruction technique, introduced by Makridakis and Nochetto. We derive novel a posteriori estimates for the norms of

L
∞

⁡
(
0
,
T
;

L
2

⁡
(
Ω
)
)

\operatorname {L}_\infty (0,T;\operatorname {L}_2(\Omega ))

and the higher order spaces,

L
∞

⁡
(
0
,
T
;

H
1

⁡
(
Ω
)
)

\operatorname {L}_\infty (0,T;\operatorname {H}^1(\Omega ))

and

H
1

⁡
(
0
,
T
;

L
2

⁡
(
Ω
)
)

\operatorname {H}^1(0,T;\operatorname {L}_2(\Omega ))

, with optimal orders of convergence.
Numerical approximations of the 10-moment Gaussian closure
Authors: Berthon Christophe
Published: August 2006

We propose a numerical scheme to approximate the weak solutions of the 10-moment Gaussian closure. The moment Gaussian closure for gas dynamics is governed by a conservative hyperbolic system supplemented by entropy inequalities whose solutions satisfy positiveness of density and tensorial pressure. We consider a Suliciu-type relaxation numerical scheme to approximate the solutions. These methods are proved to satisfy all the expected positiveness properties and all the discrete entropy inequalities. The scheme is illustrated by several numerical experiments.
A possible counterexample to well posedness of entropy solutions and to Godunov scheme convergence
Authors: Elling Volker
Published: August 2006

A particular case of initial data for the two-dimensional Euler equations is studied numerically. The results show that the Godunov method does not always converge to the physical solution, at least not on feasible grids. Moreover, they suggest that entropy solutions (in the weak entropy inequality sense) are not well posed.
On efficient computation and asymptotic sharpness of Kalantari’s bounds for zeros of polynomials
Authors: Jin Yi
Published: August 2006

We study an infinite family of lower and upper bounds on the modulus of zeros of complex polynomials derived by Kalantari. We first give a simple characterization of these bounds which leads to an efficient algorithm for their computation. For a polynomial of degree

n
n

our algorithm computes the first

m
m

bounds in Kalantari’s family in

O
(
m
n
)

O(mn)

operations. We further prove that for every complex polynomial these lower and upper bounds converge to the tightest annulus containing the roots, and thus settle a problem raised in Kalantari’s paper.
Regularization of some linear ill-posed problems with discretized random noisy data
Authors: Mathé Peter , Pereverzev Sergei
Published: August 2006

For linear statistical ill-posed problems in Hilbert spaces we introduce an adaptive procedure to recover the unknown solution from indirect discrete and noisy data. This procedure is shown to be order optimal for a large class of problems. Smoothness of the solution is measured in terms of general source conditions. The concept of operator monotone functions turns out to be an important tool for the analysis.
Fast algorithms for computing the Boltzmann collision operator
Authors: Mouhot Clément , Pareschi Lorenzo
Published: August 2006

The development of accurate and fast numerical schemes for the five-fold Boltzmann collision integral represents a challenging problem in scientific computing. For a particular class of interactions, including the so-called hard spheres model in dimension three, we are able to derive spectral methods that can be evaluated through fast algorithms. These algorithms are based on a suitable representation and approximation of the collision operator. Explicit expressions for the errors in the schemes are given and spectral accuracy is proved. Parallelization properties and adaptivity of the algorithms are also discussed.
The convergence of V-cycle multigrid algorithms for axisymmetric Laplace and Maxwell equations
Authors: Gopalakrishnan Jayadeep , Pasciak Joseph
Published: August 2006

We investigate some simple finite element discretizations for the axisymmetric Laplace equation and the azimuthal component of the axisymmetric Maxwell equations as well as multigrid algorithms for these discretizations. Our analysis is targeted at simple model problems and our main result is that the standard V-cycle with point smoothing converges at a rate independent of the number of unknowns. This is contrary to suggestions in the existing literature that line relaxations and semicoarsening are needed in multigrid algorithms to overcome difficulties caused by the singularities in the axisymmetric Maxwell problems. Our multigrid analysis proceeds by applying the well known regularity based multigrid theory. In order to apply this theory, we prove regularity results for the axisymmetric Laplace and Maxwell equations in certain weighted Sobolev spaces. These, together with some new finite element error estimates in certain weighted Sobolev norms, are the main ingredients of our analysis.
Jacobi’s last geometric statement extends to a wider class of Liouville surfaces
Authors: Sinclair Robert , Tanaka Minoru
Published: August 2006

Numerical evidence is presented which strongly suggests that “Jacobi’s last geometric statement"—that the conjugate locus from a point has exactly four cusps and the corresponding cut locus consists of only one topological segment—holds for compact real analytic Liouville surfaces diffeomorphic toS2S^2if the Gaussian curvature is everywhere positive and has exactly six critical points, these being two saddles, two global minima, and two global maxima (as is the case for an ellipsoid). Our experiments suggest that this is a sufficient rather than a necessary condition. Furthermore, for compact real analytic Liouville surfaces diffeomorphic toS2S^2upon which the Gaussian curvature can be negative but has exactly six critical points, these being two saddles, two global minima, and two global maxima, it appears that the cut locus is always a subarc of a line given byx1=constx_1=\mathrm {const}orx2=constx_2=\mathrm {const}, where(x1,x2)(x_1,x_2)are canonical coordinates with respect to which the metric has the form(f1(x1)+f2(x2))(dx12+dx22)(f_1(x_1)+f_2(x_2))(dx_1^2+dx_2^2). In the case of an ellipsoid, these curves are lines of curvature.
Early nutritional stress impairs development of a song-control brain region in both male and female juvenile song sparrows (
Melospiza melodia
) at the onset of song learning
Authors: MacDonald Ian F , Kempster Bethany , Zanette Liana , MacDougall-Shackleton Scott A
Published: August 2006

Birdsong is a sexually selected trait and is often viewed as an indicator of male quality. The developmental stress hypothesis proposes a model by which song could be an indicator; the time during early development, when birds learn complex songs and/or local variants of song, is of rapid development and nutritional stress. Birds that cope best with this stress may better learn to produce the most effective songs. The developmental stress hypothesis predicts that early food restriction should impair development of song-control brain regions at the onset of song learning. We examined the effect of food restriction on song-control brain regions in fledgling (both sexes, 23–26 days old) song sparrows (
Melospiza melodia
). Food restriction selectively reduced HVC volume in both sexes. In addition, sex differences were evident in all three song-control regions. This study lends further support to a growing body of literature documenting a variety of behavioural, physiological and neural detriments in several songbird species resulting from early developmental stress.
Invasion of an asexual American water flea clone throughout Africa and rapid displacement of a native sibling species
Authors: Mergeay Joachim , Verschuren Dirk , Meester Luc De
Published: August 2006

The huge ecological and economic impact of biological invasions creates an urgent need for knowledge of traits that make invading species successful and factors helping indigenous populations to resist displacement by invading species or genotypes. High genetic diversity is generally considered to be advantageous in both processes. Combined with sex, it allows rapid evolution and adaptation to changing environments.

We combined paleogenetic analysis with continent-wide survey of genetic diversity at nuclear and mitochondrial loci to reconstruct the invasion history of a single asexual American water flea clone (hybridDaphnia pulex×Daphnia pulicaria) in Africa. Within 60 years of the original introduction of this invader, it displaced the genetically diverse, sexual population of nativeD. pulexin Lake Naivasha (Kenya), despite a formidable numerical advantage of the local population and continuous replenishment from a large dormant egg bank. Currently, the invading clone has spread throughout the range of native AfricanD. pulex, where it appears to be the only occurring genotype.

The absence of genetic variation did not hamper either the continent-wide establishment of this exotic lineage or the effective displacement of an indigenous and genetically diverse sibling species.
Serotype cycles in cholera dynamics
Authors: Koelle Katia , Pascual Mercedes , Yunus Md
Published: August 2006

Interest in understanding strain diversity and its impact on disease dynamics has grown over the past decade. Theoretical disease models of several co-circulating strains indicate that incomplete cross-immunity generates conditions for strain-cycling behaviour at the population level. However, there have been no quantitative analyses of disease time-series that are clear examples of theoretically expected strain cycling. Here, we analyse a 40-year (1966–2005) cholera time-series from Bangladesh to determine whether patterns evident in these data are compatible with serotype-cycling behaviour. A mathematical two-serotype model is capable of explaining the oscillations in case patterns when cross-immunity between the two serotypes, Inaba and Ogawa, is high. Further support that cholera's serotype-cycling arises from population-level immunity patterns is provided by calculations of time-varying effective reproductive rates. These results shed light on historically observed serotype dominance shifts and have important implications for cholera early warning systems.
Covariance of phenotypically plastic traits induces an adaptive shift in host selection behaviour
Authors: Henry Lee M , Roitberg Bernard D , Gillespie David R
Published: August 2006

Flexibility in adult body size allows generalist parasitoids to use many host species at a cost of producing a range of adult sizes. Consequently, host selection behaviour must also maintain a level of flexibility as adult size is related to capture efficiency. In the present study, we investigated covariance of two plastic traits—size at pupation and host size selection behaviour—usingAphidius ervireared on eitherAcyrthosiphon pisumorAulacorthum solani, generating females of disparate sizes. Natal host was shown to change the ranking of perceived host quality with relation to host size. Parasitoids preferentially attacked hosts that corresponded to the size of the second instar of their natal host species. This resulted in optimal host selection behaviour when parasitoids were exposed to the same host species from which they emerged. Parasitoid size was positively correlated with host size preference, indicating that females use relative measurements when selecting suitable hosts. These coadapted gene complexes allow generalist parasitoids to effectively use multiple host species over several generations. However, the fixed nature of the behavioural response, within a parasitoid's lifetime, suggests that these traits may have evolved in a patchy host species environment.
Antimicrobial susceptibility of Neisseria gonorrhoeae isolated in Jiangsu Province, China, with a focus on fluoroquinolone resistance
Authors: Wang Bei , Xu Jin-shui , Wang Chang-xian , Mi Zu-huang , Pu Yue-pu , Hui Mamie , Ling Thomas K. W. , Chan Chiu-Yeung
Published: August 2006

In this study, the phenotypic and genotypic resistance to fluoroquinolones in Neisseria gonorrhoeae isolated in Jiangsu Province, China, was analysed. In vitro susceptibility testing of eight antimicrobial agents, including ciprofloxacin and levofloxacin, against 95 clinical isolates was carried out. Detection of mutations in the gyrA and parC genes was performed by sequence analysis. The clinical isolates demonstrated 100 % resistance to ciprofloxacin and 98.9 % non-susceptibility to levofloxacin. All of the isolates were susceptible to cefotaxime and ceftriaxone. For cefepime, spectinomycin and tetracycline, 98.9, 94.7 and 1.1 % of the isolates were susceptible, respectively. None of the isolates was susceptible to penicillin. Five types based on gyrA mutations could be categorized among 54 isolates with seven different mutation sites found on their parC gene. Analysis of sequence results showed that the gyrA mutation Asp-95→Ala and the parC mutations Ser-87→Arg and Ser-87→Asn made a significant contribution to the resistance to fluoroquinolones, in addition to double mutations found in each gene. Therefore, the use of fluoroquinolones in the treatment of N. gonorrhoeae infections in Jiangsu Province is not recommended, while the use of third- and fourth-generation cephalosporins and spectinomycin is recommended.
Contribution of the myeloperoxidase-dependent oxidative system to host defence against Cryptococcus neoformans
Authors: Aratani Yasuaki , Kura Fumiaki , Watanabe Haruo , Akagawa Hisayoshi , Takano Yukie , Ishida-Okawara Akiko , Suzuki Kazuo , Maeda Nobuyo , Koyama Hideki
Published: August 2006

Thein vivocontribution of reactive oxygen species produced by neutrophils againstCryptococcusinfection is not widely recognized. Myeloperoxidase (MPO) is a neutrophil-specific enzyme that catalyses the production of hypohalous acids such as HOCl from H2O2. This study investigated the role of MPO in immunological defence againstCryptococcus neoformansin an MPO-deficient (MPO−/−) mouse model. The survival of MPO−/−mice infected either intranasally or intravenously withC. neoformanswas lower than that of identically challenged wild-type mice. The MPO−/−mice that received intranasal injection ofC. neoformanshad significantly larger lung fungal burdens than wild-type mice. On day 7, MPO−/−mice had a significantly higher lung concentration of interleukin (IL)-4 and lower concentrations of IL-2, IL-12p70 and interferon (IFN)-γthan wild-type mice, suggesting a weak Th1 response in the MPO−/−mice toC. neoformans. Pathologically, the MPO−/−mice with intranasal infection showed more severe pneumonia than wild-type mice, which was associated with an increase in the levels of IL-1α/βin the lungs. In addition, in MPO−/−mice, the pulmonary infection disseminated to the brain with occasional meningitis. The keratinocyte-derived cytokine (KC) level in the brain of infected MPO−/−mice was higher than that of control mice. Both intranasal and intravenous infections resulted in a higher number of fungi in the spleen of MPO−/−mice compared to wild-type, suggesting decreased resistance toC. neoformansnot only in the lungs but also in the spleen in the absence of MPO. Taken together, these data suggest a major role of MPO in the response to cryptococcal infection.