scholarly journals Directional control of a processive molecular hopper

Science ◽  
2018 ◽  
Vol 361 (6405) ◽  
pp. 908-912 ◽  
Author(s):  
Yujia Qing ◽  
Sandra A. Ionescu ◽  
Gökçe Su Pulcu ◽  
Hagan Bayley
Keyword(s):  
Electric Field ◽  
Molecular Motion ◽  
External Control ◽  
Nanopore Sequencing ◽  
End Points ◽  
Dna Molecule ◽  
Directional Control ◽  
Directional Motion ◽  
The Individual

Intrigued by the potential of nanoscale machines, scientists have long attempted to control molecular motion. We monitored the individual 0.7-nanometer steps of a single molecular hopper as it moved in an electric field along a track in a nanopore controlled by a chemical ratchet. The hopper demonstrated characteristics desired in a moving molecule: defined start and end points, processivity, no chemical fuel requirement, directional motion, and external control. The hopper was readily functionalized to carry cargos. For example, a DNA molecule could be ratcheted along the track in either direction, a prerequisite for nanopore sequencing.

Experimental Control of Rhythm in Stereotyped Body Rocking

1976 ◽  
Vol 43 (2) ◽  
pp. 483-486 ◽  
Author(s):  
Peter Pohl
Keyword(s):  
External Control ◽  
Experimental Control ◽  
History Of ◽  
The Individual

A technique is described which enabled external control of the rhythm of stereotyped body rocking in a profoundly retarded, non-verbal subject. The technique consists of training the individual to synchronize the rhythm of his body rocking with an externally driven pacemaker light. Evidence is presented for experimental control of rhythm in a profoundly retarded, institutionalized child with a chronic history of body rocking.

New evidence for the life habit of graptoloids from physical modelling

Paleobiology ◽  
1989 ◽  
Vol 15 (4) ◽  
pp. 402-413 ◽  
Author(s):  
Susan Rigby ◽  
Barrie Rickards
Keyword(s):  
Narrow Band ◽  
Physical Modelling ◽  
Physical Models ◽  
Life Habit ◽  
Passive Rotation ◽  
Directional Motion ◽  
Mode Of Life ◽  
The Individual ◽  
New Evidence ◽  
Colony Shape

Physical models of graptolites have been constructed for a range of morphologies, with emphasis on planar, multiramous forms. The models are life size and have the density of a living graptolite, based on the now-established collagenous nature of the periderm and unavoidable assumptions about the amount of extrathecal tissue present in the living colony. These models have been used to test the two main hypotheses of graptolite life habit developed by Bulman, Rickards, Kirk, and others. Testing of graptoloid models in water suggests that many rhabdosome shapes were designed for passive rotation within the water column. This is caused in the models by a variety of modifications, including changes in thecal and stipe orientation, alterations of colony shape and the addition of vanes and hooks. Rotation would only have been useful when the rhabdosome was in directional motion and the frequency of such modifications seems anomalous if no such movement occurred. Thus movement by some means is required, either passively, by changes in buoyancy, or by automobility. Spiralling action would increase the harvesting path of an individual living on a planar, multiramous colony, making this a theoretically advantageous mode of life for the morphology. It would prevent the individual zooids of scandent biserial and uniserial colonies from feeding from the same narrow band of water.

Internal-External Control Orientation, Self-Description, and Bridge Playing Expertise

1972 ◽  
Vol 31 (3) ◽  
pp. 683-689 ◽  
Author(s):  
Marvin Reznikoff ◽  
Carolyn Bridges ◽  
Tannah Hirsch
Keyword(s):  
Risk Taking ◽  
Self Concept ◽  
External Control ◽  
Check List ◽  
Life Orientation ◽  
Adjective Check List ◽  
Control Orientation ◽  
The Individual ◽  
The Relationship

This study investigated the relationship between expertise in bridge playing, the degree to which the individual believes that luck or fate determine his success and self-description. Ss, 46 males and 24 females participating in a national bridge tournament, were administered Rotter's I-E scale and the Adjective Check List (ACL). Correlations of I-E scores and degree of expertness showed that the more expert males were significantly less external, indicating that they perceive bridge as much more a game of skill rather than chance. No significant correlation was found for the group of female bridge players, perhaps due to the smaller number of Ss and the greater degree of homogeneity in the group. On the ACL male experts perceived themselves as more controlled and optimistic toward life and their ability to cope with it. Female experts seemed to regard themselves as more assertive and self-confident than their less expert confreres and as having a more risk-taking life orientation. Correlations of the ACL and I-E scores indicated in general that the more internally oriented person had a more positive self-concept.

Electric field induced coil-stretch transition of DNA molecule

2019 ◽  
Vol 288 ◽  
pp. 110966
Author(s):  
Ayesha Sahreen ◽  
Adeel Ahmad
Keyword(s):  
Electric Field ◽  
Dna Molecule

Sequence stratigraphy of the late Desmoinesian to early Missourian (Pennsylvanian) succession of southern Illinois: Insights into controls on stratal architecture in an icehouse period of Earth history

2020 ◽  
Vol 90 (2) ◽  
pp. 200-227 ◽  
Author(s):  
Christopher R. Fielding ◽  
W. John Nelson ◽  
Scott D. Elrick
Keyword(s):  
Accumulation Rate ◽  
Sediment Accumulation ◽  
External Control ◽  
Illinois Basin ◽  
Carbonate Sediments ◽  
Glacial Cycles ◽  
Southern Illinois ◽  
Sequence Stratigraphic ◽  
Stratal Architecture ◽  
The Individual

ABSTRACT Uncertainty persists over whether repetitive stratal rhythms in the Pennsylvanian of Euramerica (so-called “cyclothems”) were externally forced, in all likelihood by waxing and waning of glacial ice centers on Gondwana, or were controlled by autogenic processes. A key to resolving this dispute is the lateral extent of the individual cyclothems, with broad regional extent (beyond the plausible breadth and length of individual depositional systems such as deltas) arguing in favor of an external forcing control. This study provides a sedimentological and sequence stratigraphic analysis of the middle Pennsylvanian (Desmoinesian to early Missourian in North American stratigraphic terminology, Moscovian to early Kasimovian in the terms of the global stratigraphic nomenclature) succession of the southern Illinois Basin in Illinois, Indiana, and Kentucky, eastern USA. An array of eleven lithofacies is recognized, recording deposition of clastic, humic organic, and bioclastic carbonate sediments on a broad, low-gradient, low-paleolatitude shelf and coastal plain that were undersupplied by sediment. These facies are arranged into thirteen repetitive vertical cycles (sequences), each of which can be traced across the entire basin west to east (perpendicular to the paleoslope direction) across a distance of 250 km. Sequences are bounded by erosion surfaces that define 1–4 km-wide, deeply incised valley-fills (IVFs) that are mostly elongate towards the south-southwest, the dominant direction of paleoflow. In the west–east direction, valley erosion surfaces pass laterally into well-developed paleosols, incised locally by smaller channels. Each of these surfaces is laterally persistent across the basin. IVFs comprise multi-story bodies of conglomerate–breccia and sandstone, passing upward into heterolithic sandstone–mudrock associations, recording fluvial and later estuarine environments. Coal bodies typically occur at the tops of IVFs and are interbedded with heterolithic facies recording tidal influence, indicative of initial flooding by the sea. They are in turn overlain by estuarine and marine mudrocks and bioclastic carbonates, recording the maximum extent of marine flooding in a cycle. Each sequence is completed by heterolithic to sandstone-dominated facies of deltaic aspect that are typically truncated by the next erosion surface (sequence boundary). Plausible modern analogs suggest that sea-level excursions were of the order of 20–40 m. The great lateral persistence of not only the thirteen sequences, but also many of their component beds, argues strongly for an external control on sediment accumulation. Eccentricity-paced glacial cycles in Gondwana are invoked as the most likely cause of the cyclicity. The low-accommodation context of the Illinois Basin (average accumulation rate 6 cm/ky) contributed to the incomplete, condensed, and strongly top-truncated nature of preserved sequences.

scholarly journals Tavola Rotonda su: “Fattori prognostici e markers nel carcinoma della vescica”. Aspetti generali e introduttivi: Round Table on: “Prognostic factors and markers in bladder carcinoma”. General and introductory aspects

1995 ◽  
Vol 62 (2) ◽  
pp. 163-167
Author(s):  
G. Mobilio
Keyword(s):  
Prognostic Factors ◽  
Bladder Carcinoma ◽  
Predictive Value ◽  
Clinical Studies ◽  
Specific Treatment ◽  
Immunological Response ◽  
Round Table ◽  
End Points ◽  
The Individual ◽  
Bladder Tumours

Bladder tumours are generally grouped as superficial or invasive because of their different therapeutical regimens. Superficial tumours still cause uncertainties in choosing the best treatment due to their heterogeneity and different behaviour. In the prevision of these tumours it is important to consider all the factors that could influence the prognosis: tumoral characteristics, grading and staging mistakes, effects of the therapy and immunological response. Moreover it is important for clinical studies to have appropriate end points. Prognostic factors and markers with high predictive value can allow specific treatment for the individual cases to be planned.

Substituent-induced 1H chemical shifts for 4-substituted (2, 2-dichlorocyclopropyl)benzenes: further evidence for intramolecular electric field effects on 1H chemical shifts

1977 ◽  
Vol 55 (3) ◽  
pp. 530-535 ◽  
Author(s):  
Robert H. Kohler ◽  
William F. Reynolds
Keyword(s):  
Electric Field ◽  
Field Effect ◽  
Ring Current ◽  
Chemical Shifts ◽  
Basic Pattern ◽  
Electric Field Effects ◽  
Field Effects ◽  
The Individual ◽  
Induced Changes ◽  
Proton Chemical Shifts

Correlations of cyclopropyl proton chemical shifts for 4-substituted (2,2-dichlorocyclopropyl)-benzenes with σI and σR0 provide evidence that these chemical shifts reflect direct field effects and weak phenyl–cyclopropyl conjugative interactions. Corrections for variable ring current effects due to substituent-induced changes in conformation improve the individual correlations but do not alter the basic pattern of results. Correlation of the β cyclopropyl 1H chemical shift difference with σI with calculated hydrogen electron densities, and with calculated electric field components provides further strong evidence for a field effect on 1H chemical shifts.

BERRY PHASE IN COUPLED TWO-LEVEL SYSTEMS

2013 ◽  
Vol 27 (12) ◽  
pp. 1350088 ◽  
Author(s):  
X. Y. ZHANG ◽  
J. H. TENG ◽  
X. X. YI
Keyword(s):  
Asymptotic Behavior ◽  
Geometric Phase ◽  
Berry Phase ◽  
External Control ◽  
Control Parameters ◽  
Coupling Constant ◽  
Geometric Phases ◽  
Coupled Subsystems ◽  
Two Level Systems ◽  
The Individual

The application of geometric phases into robust control of quantal systems has triggered exploration of the geometric phase for coupled subsystems. Earlier studies have mainly focused on the situation where the external control parameters are in the free Hamiltonian of the subsystems, i.e. the controls exert only on the individual subsystems. Here we consider another circumstance that we can control the coupling geiϕ between the subsystems. By changing only the phase ϕ in the coupling constant, we derive the Berry phase acquired by the system and compare it to the geometric phase acquired by changing the coupling strength g. We find that the asymptotic behavior of the Berry phase depends on the relative Rabi frequency of the two subsystems, and it approaches π when the amplitude of the coupling tends to infinity.

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