1,112 research outputs found
Spectral and Temporal Variability of Earth Observed in Polarization
We present a comprehensive set of spectropolarimetric observations of
Earthshine as obtained by FORS2 at the VLT for phase angles from 50degree to
135degree (Sun-Earth-Moon angle), covering a spectral range from 430nm to
920nm. The degree of polarization in BVRI passbands, the differential
polarization vegetation index, and the equivalent width of the O2A polarization
band around 760nm are determined with absolute errors around 0.1 percent in the
degree of polarization. Earthshine polarization spectra are corrected for the
effect of depolarization introduced by backscattering on the lunar surface,
introducing systematic errors of the order of 1 percent in the degree of
polarization. Distinct viewing sceneries such as observing the Atlantic or
Pacific side in Earthshine yield statistically different phase curves. The
equivalent width defined for the O2A band polarization is found to vary from
-5nm to +2nm. A differential polarized vegetation index is introduced and
reveals a larger vegetation signal for those viewing sceneries that contain
larger fractions of vegetated surface areas. We corroborate the observed
correlations with theoretical models from the literature, and conclude that the
Vegetation Red Edge(VRE) is a robust and sensitive signature in polarization
spectra of planet Earth. The overall behaviour of polarization of planet Earth
in the continuum and in the O2A band can be explained by existing models.
Biosignatures such as the O2A band and the VRE are detectable in Earthshine
polarization with a high degree of significance and sensitivity. An in-depth
understanding of Earthshines temporal and spectral variability requires
improved models of Earths biosphere, as a prerequisite to interpret possible
detections of polarised biosignatures in earthlike exoplanets in the future.Comment: 19 pages, 14 figures, 3 table
DEVELOPMENT OF VIRTUAL EVENT MARKETING
In the last few years the Pichia pastoris expression system has been gaining more and more interest for the expression of recombinant proteins. Many groups have employed fermentation technology in their investigations because the system is fairly easy to scale up and suitable for the production in the milligram to gram range. A large number of heterologous proteins from different sources has been expressed, but the fermentation process technology has been investigated to a lesser extent. A large number of fermentations are carried out in standard bioreactors that may be insufficiently equipped to meet the demands of high-cell-density fermentations of methylotrophic yeasts. In particular, the lack of on-line methanol analysis leads to fermentation protocols that may impair the optimal expression of the desired products. We have used a commercially available methanol sensor to investigate in detail the effects of supplementary glycerol feeding while maintaining a constant methanol concentration during the induction of a Mut+ strain of Pichia pastoris. Specific glycerol feed rates in the range of 38-4.2 mg × g(exp -1) × h(exp -1) (mg glycerol per gram fresh weight per hour) were investigated. Expression of the recombinant scFv antibody fragment was only observed at specific feed rates below 6 mg × g(exp -1) × h(exp -1). At low specific feed rates, growth was even lower than with methanol as the sole carbon source and the harvest expression level of the scFv was only half of that found in the control fermentation. These results show that glycerol inhibits expression driven by the AOX1 promoter even at extremely limited availability and demonstrate the benefits of on-line methanol control in Pichia fermentation research
Searching of gapped repeats and subrepetitions in a word
A gapped repeat is a factor of the form where and are nonempty
words. The period of the gapped repeat is defined as . The gapped
repeat is maximal if it cannot be extended to the left or to the right by at
least one letter with preserving its period. The gapped repeat is called
-gapped if its period is not greater than . A
-subrepetition is a factor which exponent is less than 2 but is not
less than (the exponent of the factor is the quotient of the length
and the minimal period of the factor). The -subrepetition is maximal if
it cannot be extended to the left or to the right by at least one letter with
preserving its minimal period. We reveal a close relation between maximal
gapped repeats and maximal subrepetitions. Moreover, we show that in a word of
length the number of maximal -gapped repeats is bounded by
and the number of maximal -subrepetitions is bounded by
. Using the obtained upper bounds, we propose algorithms for
finding all maximal -gapped repeats and all maximal
-subrepetitions in a word of length . The algorithm for finding all
maximal -gapped repeats has time complexity for the case
of constant alphabet size and time complexity for the
general case. For finding all maximal -subrepetitions we propose two
algorithms. The first algorithm has time
complexity for the case of constant alphabet size and time complexity for the general case. The
second algorithm has
expected time complexity
Quantitative Models and Implicit Complexity
We give new proofs of soundness (all representable functions on base types
lies in certain complexity classes) for Elementary Affine Logic, LFPL (a
language for polytime computation close to realistic functional programming
introduced by one of us), Light Affine Logic and Soft Affine Logic. The proofs
are based on a common semantical framework which is merely instantiated in four
different ways. The framework consists of an innovative modification of
realizability which allows us to use resource-bounded computations as realisers
as opposed to including all Turing computable functions as is usually the case
in realizability constructions. For example, all realisers in the model for
LFPL are polynomially bounded computations whence soundness holds by
construction of the model. The work then lies in being able to interpret all
the required constructs in the model. While being the first entirely semantical
proof of polytime soundness for light logi cs, our proof also provides a
notable simplification of the original already semantical proof of polytime
soundness for LFPL. A new result made possible by the semantic framework is the
addition of polymorphism and a modality to LFPL thus allowing for an internal
definition of inductive datatypes.Comment: 29 page
Hydrated Electron Dynamics at a Five Femtosecond Time Scale
Hydrated electrons are studied by frequency resolved pump probe with 5 fs time resolution in the spectral range from 600 nm to 1000 nm. A recurrence detected in the pumpprobe signal at —40 fs is tentatively assigned to coupling to librational motions in the electron's solvent cage
Investigation of a Bubble Detector based on Active Electrolocation of Weakly Electric Fish
Weakly electric fish employ active electrolocation for navigation and object detection. They emit an electric signal with their electric organ in the tail and sense the electric field with electroreceptors that are distributed over their skin. We adopted this principle to design a bubble detector that can detect gas bubbles in a fluid or, in principle, objects with different electric conductivity than the surrounding fluid. The evaluation of the influence of electrode diameter on detecting a given bubble size showed that the signal increases with electrode diameter. Therefore it appears that this detector will be more appropriate for large sized applications such as bubble columns than small sized applications such as bubble detectors in dialysis
The Cambridge Grammar of Classical Greek. A New Reference Grammar for Classical Greek: aims and principles
The Cambridge Grammar of Classical Greek. A New Reference Grammar for Classical Greek: aims and principles
Optimal Color Range Reporting in One Dimension
Color (or categorical) range reporting is a variant of the orthogonal range
reporting problem in which every point in the input is assigned a \emph{color}.
While the answer to an orthogonal point reporting query contains all points in
the query range , the answer to a color reporting query contains only
distinct colors of points in . In this paper we describe an O(N)-space data
structure that answers one-dimensional color reporting queries in optimal
time, where is the number of colors in the answer and is the
number of points in the data structure. Our result can be also dynamized and
extended to the external memory model
Quasiperiodicity and non-computability in tilings
We study tilings of the plane that combine strong properties of different
nature: combinatorial and algorithmic. We prove existence of a tile set that
accepts only quasiperiodic and non-recursive tilings. Our construction is based
on the fixed point construction; we improve this general technique and make it
enforce the property of local regularity of tilings needed for
quasiperiodicity. We prove also a stronger result: any effectively closed set
can be recursively transformed into a tile set so that the Turing degrees of
the resulted tilings consists exactly of the upper cone based on the Turing
degrees of the later.Comment: v3: the version accepted to MFCS 201
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