248 research outputs found
Complexity-entropy analysis at different levels of organization in written language
Written language is complex. A written text can be considered an attempt to
convey a meaningful message which ends up being constrained by language rules,
context dependence and highly redundant in its use of resources. Despite all
these constraints, unpredictability is an essential element of natural
language. Here we present the use of entropic measures to assert the balance
between predictability and surprise in written text. In short, it is possible
to measure innovation and context preservation in a document. It is shown that
this can also be done at the different levels of organization of a text. The
type of analysis presented is reasonably general, and can also be used to
analyze the same balance in other complex messages such as DNA, where a
hierarchy of organizational levels are known to exist
Complexity and transition to chaos in coupled Adler-type oscillators
Coupled non-linear oscillators are ubiquitous in dynamical studies. A wealth
of behaviors have been found mostly for globally coupled systems. From a
complexity perspective, less studied have been systems with local coupling,
which is the subject of this contribution. The phase approximation is used, as
weak coupling is assumed. In particular, the so called needle region, in
parameter space, for Adler-type oscillators with nearest neighbors coupling is
carefully characterized. The reason for this emphasis is that in the border of
this region to the surrounding chaotic one, computation enhancement at the edge
of chaos has been reported. The present study shows that different behaviors
within the needle region can be found, and a smooth change of dynamics could be
identified. Entropic measures further emphasize the region's heterogeneous
nature with interesting features, as seen in the spatiotemporal diagrams. The
occurrence of wave-like patterns in the spatiotemporal diagrams points to
non-trivial correlations in both dimensions. The wave patterns change as the
control parameters change without exiting the needle region. Spatial
correlation is only achieved locally at the onset of chaos, with different
clusters of oscillators behaving coherently while disordered boundaries appear
between them.Comment: revised version published in PHYSICAL REVIEW E 107, 044212 (2023
Transfer Matrices and Excitations with Matrix Product States
We investigate the relation between static correlation functions in the
ground state of local quantum many-body Hamiltonians and the dispersion
relations of the corresponding low energy excitations using the formalism of
tensor network states. In particular, we show that the Matrix Product State
Transfer Matrix (MPS-TM) - a central object in the computation of static
correlation functions - provides important information about the location and
magnitude of the minima of the low energy dispersion relation(s) and present
supporting numerical data for one-dimensional lattice and continuum models as
well as two-dimensional lattice models on a cylinder. We elaborate on the
peculiar structure of the MPS-TM's eigenspectrum and give several arguments for
the close relation between the structure of the low energy spectrum of the
system and the form of static correlation functions. Finally, we discuss how
the MPS-TM connects to the exact Quantum Transfer Matrix (QTM) of the model at
zero temperature. We present a renormalization group argument for obtaining
finite bond dimension approximations of MPS, which allows to reinterpret
variational MPS techniques (such as the Density Matrix Renormalization Group)
as an application of Wilson's Numerical Renormalization Group along the virtual
(imaginary time) dimension of the system.Comment: 39 pages (+8 pages appendix), 14 figure
Antibiotic Resistance of Human Periodontal Pathogen Parvimonas micra Over 10 Years
Changes were evaluated over 10 years in the in vitro resistance of human periodontopathic strains of Parvimonas micra to four antibiotics. Subgingival biofilms culture positive for P. micra from 300 United States adults with severe periodontitis in 2006, and from a similar group of 300 patients in 2016, were plated onto anaerobically incubated enriched Brucella blood agar alone, or supplemented with either doxycycline (4 mg/L), clindamycin (4 mg/L), amoxicillin (8 mg/L), or metronidazole (16 mg/L). P. micra growth on antibiotic-supplemented media indicated in vitro resistance to the evaluated antibiotic concentration. P. micra resistance was significantly more frequent among patients in 2016, as compared to 2006, for doxycycline (11.3% vs. 0.3% patients; 37.7-fold increase), and clindamycin (47.3% vs. 2.0% patients; 23.7-fold increase) (both p 0.05). No P. micra isolates in 2006 or 2016 were jointly resistant in vitro to both amoxicillin and metronidazole. The alarming increases in subgingival P. micra resistance to doxycycline and clindamycin raise serious questions about the empiric use of these antibiotics, either locally or systemically, in the treatment of United States periodontitis patients harboring subgingival P. micra
Non-uniqueness of ergodic measures with full Hausdorff dimension on a Gatzouras-Lalley carpet
In this note, we show that on certain Gatzouras-Lalley carpet, there exist
more than one ergodic measures with full Hausdorff dimension. This gives a
negative answer to a conjecture of Gatzouras and Peres
Comparative In Vitro Resistance of Human Periodontal Bacterial Pathogens to Tinidazole and Four Other Antibiotics
The in vitro resistance of selected red/orange complex periodontal pathogens to tinidazole was compared with four other antibiotics. Subgingival biofilm samples from 88 adults with severe periodontitis were anaerobically incubated on enriched Brucella blood agar with and without supplementation with tinidazole (16 mg/L), metronidazole (16 mg/L), amoxicillin (8 mg/L), doxycycline (4 mg/L), or clindamycin (4 mg/L). Growth of Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Fusobacterium nucleatum, Streptococcus constellatus, or Campylobacter rectus on antibiotic-supplemented plates indicated their in vitro antibiotic resistance. Tinidazole inhibited all test species, except P. intermedia/nigrescens, P. micra, and S. constellatus in 3.8%, 10.2%, and 88.9% of species-positive patients, respectively. Significantly fewer patients yielded tinidazole-resistant test species, and had significantly lower subgingival proportions of tinidazole-resistant organisms, than patients with amoxicillin, doxycycline, or clindamycin-resistant species, but not those with metronidazole-resistant strains. Joint in vitro species resistance to tinidazole and amoxicillin, or metronidazole and amoxicillin, was rare. Tinidazole performed in vitro similar to metronidazole, and markedly better than amoxicillin, doxycycline, or clindamycin, against fresh clinical isolates of red/orange complex periodontal pathogens. As a result of its similar antimicrobial spectrum, and more convenient once-a-day oral dosing, tinidazole should be considered in place of metronidazole for systemic periodontitis drug therapy
Evaluation of a Rapid Biological Spore Test for Dental Instrument Sterilization
Aim: This study evaluated the reliability of a new rapid biological spore test (BST) for determining the sterilization efficacy of dental steam autoclaves within 20 minutes, as compared to a conventional BST requiring 2 days of incubation after autoclave exposure.Materials and methods: A total of 177 pairs of BST, each composed of a rapid test (Celerity™ 20 Steam Biologic Indicator, Steris) and a conventional BST (Attest™ 1262 Biological Indicator, 3M), both containing Geobacillus stearothermophilus spores, were placed into steam autoclaves loaded with instruments, and subjected to either sterilizing (157 pairs) or non-sterilizing conditions (20 pairs). Celerity™ BST was then incubated for 20 minutes at 57°C, with the growth medium evaluated spectrophotometrically for fluorescent α-glucosidase signal changes (no change with successful sterilization; increased fluorescence after failed sterilization). Attest™ BST was incubated for 48 hours at 57°C, after which a pH-based color change in the culture broth was visually assessed (no change in purple color with successful sterilization; change to yellow color with failed sterilization).Results: Celerity™ and Attest™ BST both accurately identified successful sterilization, with no G. stearothermophilus spore growth from either BST after exposure to sterilizing steam autoclave conditions (100% agreement between 157 pairs of each BST). Both BST also accurately detected unsuccessful sterilization, with all tested ampoules positive for G. stearothermophilus spore germination after non-sterilizing steam autoclave time periods. Both BST exhibited 100% sensitivity, specificity, and accuracy for detection of sterilizing steam autoclave conditions.Conclusion: Celerity™ BST, after only 20 minutes incubation, performed equally as well as a BST requiring 48 hours incubation in determining the sterilization efficacy of dental steam autoclaves.Clinical significance: Rapid BST offer earlier detection of sterilization failure before potentially contaminated dental instruments are used in clinical patient care.</p
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