104 research outputs found
Genomic architecture of adaptive radiation and hybridization in Alpine whitefish
Adaptive radiations represent some of the most remarkable explosions of
diversification across the tree of life. However, the constraints to rapid diver-
sification and how they are sometimes overcome, particularly the relative roles
of genetic architecture and hybridization, remain unclear. Here, we address
these questions in the Alpine whitefish radiation, using a whole-genome
dataset that includes multiple individuals of each of the 22 species belonging
to six ecologically distinct ecomorph classes across several lake-systems. We
reveal that repeated ecological and morphological diversification along a
common environmental axis is associated with both genome-wide allele fre-
quency shifts and a specific, larger effect, locus, associated with the gene edar.
Additionally, we highlight the possible role of introgression between species
from different lake-systems in facilitating the evolution and persistence of
species with unique trait combinations and ecology. These results highlight
the importance of both genome architecture and secondary contact with
hybridization in fuelling adaptive radiation
A pattern-recognition theory of search in expert problem solving
Understanding how look-ahead search and pattern recognition interact is one of the important research questions in the study of expert problem-solving. This paper examines the implications of the template theory (Gobet & Simon, 1996a), a recent theory of expert memory, on the theory of problem solving in chess. Templates are "chunks" (Chase & Simon, 1973) that have evolved into more complex data structures and that possess slots allowing values to be encoded rapidly. Templates may facilitate search in three ways: (a) by allowing information to be stored into LTM rapidly; (b) by allowing a search in the template space in addition to a search in the move space; and (c) by compensating loss in the "mind's eye" due to interference and decay. A computer model implementing the main ideas of the theory is presented, and simulations of its search behaviour are discussed. The template theory accounts for the slight skill difference in average depth of search found in chess players, as well as for other empirical data
A Third Measure-Metastable State in the Dynamics of Spontaneous Shape Change in Healthy Human's White Cells
Human polymorphonuclear leucocytes, PMN, are highly motile cells with average 12-15 ”m diameters and prominent, loboid nuclei. They are produced in the bone marrow, are essential for host defense, and are the most populous of white blood cell types. PMN also participate in acute and chronic inflammatory processes, in the regulation of the immune response, in angiogenesis, and interact with tumors. To accommodate these varied functions, their behavior is adaptive, but still definable in terms of a set of behavioral states. PMN morphodynamics have generally involved a non-equilibrium stationary, spheroid Idling state that transitions to an activated, ellipsoid translocating state in response to chemical signals. These two behavioral shape-states, spheroid and ellipsoid, are generally recognized as making up the vocabulary of a healthy PMN. A third, ârandomâ state has occasionally been reported as associated with disease states. I have observed this third, Treadmilling state, in PMN from healthy subjects, the cells demonstrating metastable dynamical behaviors known to anticipate phase transitions in mathematical, physical, and biological systems. For this study, human PMN were microscopically imaged and analyzed as single living cells. I used a microscope with a novel high aperture, cardioid annular condenser with better than 100 nanometer resolution of simultaneous, mixed dark field and intrinsic fluorescent images to record shape changes in 189 living PMNs. Relative radial roundness, R(t), served as a computable order parameter. Comparison of R(t) series of 10 cells in the Idling and 10 in the Treadmilling state reveals the robustness of the ârandomâ appearing Treadmilling state, and the emergence of behaviors observed in the neighborhood of global state transitions, including increased correlation length and variance (divergence), sudden jumps, mixed phases, bimodality, power spectral scaling and temporal slowing. Wavelet transformation of an R(t) series of an Idling to Treadmilling state change, demonstrated behaviors concomitant with the observed transition
Quantitative analysis by renormalized entropy of invasive electroencephalograph recordings in focal epilepsy
Invasive electroencephalograph (EEG) recordings of ten patients suffering
from focal epilepsy were analyzed using the method of renormalized entropy.
Introduced as a complexity measure for the different regimes of a dynamical
system, the feature was tested here for its spatio-temporal behavior in
epileptic seizures. In all patients a decrease of renormalized entropy within
the ictal phase of seizure was found. Furthermore, the strength of this
decrease is monotonically related to the distance of the recording location to
the focus. The results suggest that the method of renormalized entropy is a
useful procedure for clinical applications like seizure detection and
localization of epileptic foci.Comment: 10 pages, 5 figure
Combined effects of franchise management strategies and employee service performance on customer loyalty: a multilevel perspective
Although franchisee performance is likely to be influenced by franchisorsâ management strategies, little is known about whether and how franchisorsâ strategies affect franchisee employeesâ performance. This study examines the combined effects of three franchisor management strategies, namely innovative culture, support services and autonomy on service performance of the franchisee store employees and the loyalty of their customers. Data were collected from a total of 38 employees and 679 customers of 25 franchisee stores. The study employs multilevel analysis on a nested data-set created by matching customer data with employee data for each store. The results reveal that customer loyalty of a franchisee store is positively influenced by the service performance of its employees and the support services received by the employees of the store from its franchisor. On the other hand, it has been found that franchisor management strategy such as innovative culture and autonomy negatively influence customer loyalty of the franchisee store. The paper discusses relevant theoretical and managerial implications of the findings
PROTDES: CHARMM toolbox for computational protein design
We present an open-source software able to automatically mutate any residue positions and find the best aminoacids in an arbitrary protein structure without requiring pairwise approximations. Our software, PROTDES, is based on CHARMM and it searches automatically for mutations optimizing a protein folding free energy. PROTDES allows the integration of molecular dynamics within the protein design. We have implemented an heuristic optimization algorithm that iteratively searches the best aminoacids and their conformations for an arbitrary set of positions within a structure. Our software allows CHARMM users to perform protein design calculations and to create their own procedures for protein design using their own energy functions. We show this by implementing three different energy functions based on different solvent treatments: surface area accessibility, generalized Born using molecular volume and an effective energy function. PROTDES, a tutorial, parameter sets, configuration tools and examples are freely available at http://soft.synth-bio.org/protdes.html
Correlation between clinical performance and degree of conversion of resin cements: a literature review
AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used
Biological markers of alcohol consumption in alcoholised drivers: Comparison of capillary electrophoresis (CZE CDT) and a direct immunoassay (N Latex CDT) with the traditional method of anion-exchange chromatography-immunoturbidimetry (%CDT TIA).
Objectives: The aim of this study was to compare specificity and sensitivity of different biological markers that
can be used in a forensic field to identify potentially dangerous drivers because of their alcohol
habits.
Methods: We studied 280 Swiss drivers after driving while under the alcohol influence. 33 were excluded for
not having CDT N results, 247 were included (218 men (88%) and 29 women (12%). Mean age was
42,4 (SD:12, min: 20 max: 76). The evaluation of the alcohol consumption concerned the month
before the CDT test and was considered as such after the interview: Heavy drinkers (>3 drinks per
day): 60 (32.7%), < 3 drinks per day and moderate: 127 (51.4%) 114 (46.5%), abstinent: 60 (24.3%)
51 (21%). Alcohol intake was monitored by structured interviews, self-reported drinking habits and
the C-Audit questionnaire as well as information provided by their family and general practitioner.
Consumption was quantified in terms of standard drinks, which contain approximately 10 grams of
pure alcohol (Ref. WHO).
Results: comparison between moderate (less or equal to 3 drinks per day) and excessive drinkers (more than
3 drinks)
Marker ROC area 95% CI cut-off sensitivity specificity
CDT TIA 0.852 0.786-0917 2.6* 0.93
LR+1.43
0.35
LR-0.192
CDT N latex 0.875 0.821-0.930 2.5* 0.66
LR+ 6.93
0.90
LR- 0.369
Asialo+disialo-tf 0.881 0.826-0.936 1.2* 0.78
LR+4.07
0.80
LR-0.268
1.7° 0.66
LR+8.9
0.93
LR-0.360
GGT 0.659 0.580-0.737 85* 0.37
LR+2.14
0.83
LR-0.764
* cut-off point suggested by the manufacturer
° cut-off point suggested by our laboratory
Conclusion: With the cut-off point established by the manufacturer, CDT TIA performed poorly in term of
specificity. N latex CDT and CZE CDT were better, especially if a 1.7 cut-off is used with CZ
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