819 research outputs found
Bird migration and the spread of Crustacea. [Translation from: Verhandlungen der Deutschen Zoologischen Gesellschaft 27, 311-316, 1963.]
The passive spread of a high percentage of freshwater organisms is one of the most important requirements in short-lived and insular communities for species to attai n and survive - and consequently to balance the lack of a topographical continuity of most inland waters. Unfortunately hardly anything is known about the amounts of seed material typical for any lake into which it is carried. The causes of passive dissemination - wind, water and animals as well as man - are confirmed by many examples. It has been assumed now for at least a hundered years that , among animals, birds play a prominent role, although also disappointingly few facts are at hand. The passage and spread through birds' intestines has up to now been supported only by some limited data. This paper reports on experimental research where the eggs of Daphnia magna, Triops cancriformis, Artemia salina, Diaptomus spinosus and Cypris pubera were introduced by means of gelatine capsules into the oesophagus of a drake. The bird's excrements were inspected under a microscope for eggs and resting stages, and these were transferred into corresponding cultures
Evolutionary dynamics of incubation periods
The incubation period of a disease is the time between an initiating
pathologic event and the onset of symptoms. For typhoid fever, polio, measles,
leukemia and many other diseases, the incubation period is highly variable.
Some affected people take much longer than average to show symptoms, leading to
a distribution of incubation periods that is right skewed and often
approximately lognormal. Although this statistical pattern was discovered more
than sixty years ago, it remains an open question to explain its ubiquity. Here
we propose an explanation based on evolutionary dynamics on graphs. For simple
models of a mutant or pathogen invading a network-structured population of
healthy cells, we show that skewed distributions of incubation periods emerge
for a wide range of assumptions about invader fitness, competition dynamics,
and network structure. The skewness stems from stochastic mechanisms associated
with two classic problems in probability theory: the coupon collector and the
random walk. Unlike previous explanations that rely crucially on heterogeneity,
our results hold even for homogeneous populations. Thus, we predict that two
equally healthy individuals subjected to equal doses of equally pathogenic
agents may, by chance alone, show remarkably different time courses of disease.Comment: 24 pages, 8 figures, 1 tabl
Electro-optic polarization tuning of microcavities with a single quantum dot
We present an oxide aperture microcavity with embedded quantum dots that
utilizes a three contact design to independently tune the quantum dot
wavelength and birefringence of the cavity modes. A polarization splitting
tuning of 5 GHz is observed. For typical microcavity polarization
splittings, the method can be used to achieve perfect polarization degeneracy
that is required for many polarization-based implementations of photonic
quantum gates. The embedded quantum dot wavelength can be tuned into resonance
with the cavity, independent of the polarization tuning
Cavity induced modifications to the resonance fluorescence and probe absorption of a laser-dressed V atom
A cavity-modified master equation is derived for a coherently driven, V-type
three-level atom coupled to a single-mode cavity in the bad cavity limit. We
show that population inversion in both the bare and dressed-state bases may be
achieved, originating from the enhancement of the atom-cavity interaction when
the cavity is resonant with an atomic dressed-state transition. The atomic
populations in the dressed state representation are analysed in terms of the
cavity-modified transition rates. The atomic fluorescence spectrum and probe
absorption spectrum also investigated, and it is found that the spectral
profiles may be controlled by adjusting the cavity frequency. Peak suppression
and line narrowing occur under appropriate conditions.Comment: 12 pages, 10 postscript figures, to be appeared in Phys. Rev.
ΠΡΠΎΠ΅ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠΈΡΡΠ΅ΠΌΡ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΠ·Π°ΡΠΈΠΈ ΠΈ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ ΡΠ·Π»Π° ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ°ΡΡΠ²ΠΎΡΠ° ΡΡΠ°Π½ΠΈΠ»Π½ΠΈΡΡΠ°ΡΠ°
ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»ΡΠ΅ΡΡΡ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½Π°Ρ ΡΠΈΡΡΠ΅ΠΌΠ°
ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠΌ ΡΠ·Π»Π° ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ°ΡΡΠ²ΠΎΡΠ°
ΡΡΠ°Π½ΠΈΠ»Π½ΠΈΡΡΠ°ΡΠ°. Π¦Π΅Π»Ρ ΡΠ°Π±ΠΎΡΡ β ΡΠΎΠ·Π΄Π°Π½ΠΈΠ΅ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΡ ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ
ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠΌ ΡΠ·Π»Π° ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠ°ΡΡΠ²ΠΎΡΠ° ΡΡΠ°Π½ΠΈΠ»Π½ΠΈΡΡΠ°ΡΠ°.
Π ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΎΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΈΠ·ΡΡΠ΅Π½ΠΈΠ΅
ΡΡΡΠ΅ΡΡΠ²ΡΡΡΠΈΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΎΡΠ΅Π½ΠΊΠΈ Π°ΠΏΠΏΠ°ΡΠ°ΡΠ½ΠΎΠΉ ΠΈ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠ½ΠΎΠΉ Π½Π°Π΄Π΅ΠΆΠ½ΠΎΡΡΠΈ ΠΠ‘Π£
Π’Π.The subject of the study is an automated system
Control of the technological process of the solution concentration unit
Uranyl nitrate. The purpose of the work is the creation of an automated control system
Technological process of the unit of concentration of a solution of uranyl nitrate.
During the research, a study was conducted, as well as a study
Existing methods for evaluating the hardware and software reliability of the control system
TP
Evolution of a periodic eight-black-hole lattice in numerical relativity
The idea of black-hole lattices as models for the large-scale structure of
the universe has been under scrutiny for several decades, and some of the
properties of these systems have been elucidated recently in the context of the
problem of cosmological backreaction. The complete, three-dimensional and fully
relativistic evolution of these system has, however, never been tackled. We
explicitly construct the first of these solutions by numerically integrating
Einstein's equation in the case of an eight-black-hole lattice with the
topology of S3.Comment: 21 pages, 13 figures. Corrected and clarified discussio
Formation of Giant Quasibound Cold Diatoms by Strong Atom-Cavity Coupling
We show that giant quasi-bound diatomic complexes, whose size is typically
hundreds of nm, can be formed by intra-cavity cold diatom photoassociation or
photodissociation in the strong atom-cavity coupling regime.Comment: 4 pages, 3 figure
Mutations in pericentrin cause Seckel syndrome with defective ATR-dependent DNA damage signaling
Large brain size is one of the defining characteristics of modern humans. Seckel syndrome (MIM 210600), a disorder of markedly reduced brain and body size, is associated with defective ATR-dependent DNA damage signaling. Only a single hypomorphic mutation of ATR has been identified in this genetically heterogeneous condition. We now report that mutations in the gene encoding pericentrin (PCNT)--resulting in the loss of pericentrin from the centrosome, where it has key functions anchoring both structural and regulatory proteins--also cause Seckel syndrome. Furthermore, we find that cells of individuals with Seckel syndrome due to mutations in PCNT (PCNT-Seckel) have defects in ATR-dependent checkpoint signaling, providing the first evidence linking a structural centrosomal protein with DNA damage signaling. These findings also suggest that other known microcephaly genes implicated in either DNA repair responses or centrosomal function may act in common developmental pathways determining human brain and body size
Common principles and best practices for engineering microbiomes
Despite broad scientific interest in harnessing the power of Earth's microbiomes, knowledge gaps
hinder their efficient use for addressing urgent societal and environmental challenges. We argue
hat structuring research and technology developments around a design-build-test-learn (DBTL)
cycle will advance microbiome engineering and spur new discoveries on the basic scientific
principles governing microbiome function. In this Review, we present key elements of an
iterative DBTL cycle for microbiome engineering, focusing on generalizable approaches,
including top-down and bottom-up design processes, synthetic and self-assembled construction
methods, and emerging tools to analyze microbiome function. These approaches can be used to
harness microbiomes for broad applications related to medicine, agriculture, energy, and the
environment. We also discuss key challenges and opportunities of each approach and synthesize
them into best practice guidelines for engineering microbiomes. We anticipate that adoption of a
DBTL framework will rapidly advance microbiome-based biotechnologies aimed at improving
human and animal health, agriculture, and enabling the bioeconomy
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