scholarly journals Selected topics in scalar–tensor theories and beyond

2019 ◽  
Vol 28 (07) ◽  
pp. 1930012 ◽  
Author(s):  
Israel Quiros
Keyword(s):  
Theoretical Perspective ◽  
Scalar Fields ◽  
Theory Of Relativity ◽  
Postgraduate Students ◽  
Higher Derivative ◽  
Long Time ◽  
Theories Of Gravity ◽  
Weyl Symmetry ◽  
Stability Issues ◽  
First Time

Scalar fields have played an important role in the development of the fundamental theories of physics as well as in other branches of physics such as gravitation and cosmology. For a long time, these escaped detection until 2012 when the Higgs boson was observed for the first time. Since then, alternatives to the general theory of relativity like the Brans–Dicke (BD) theory, scalar–tensor theories of gravity and their higher derivative generalizations — collectively known as Horndeski theories — have acquired renewed interest. In the present review, we discuss several selected topics regarding these theories, mainly from the theoretical perspective but with due mention of the observational aspect. Among the topics covered in this review, we pay special attention to the following: (1) the asymptotic dynamics of cosmological models based on the BD, scalar–tensor and Horndeski theories, (2) inflationary models, extended quintessence and the Galileons, with emphasis in causality and stability issues, (3) the chameleon and Vainshtein screening mechanisms that may allow the elusive scalar field to evade the tight observational constraints implied by the solar system experiments, (4) the conformal frames conundrum with a brief discussion on the disformal transformations and (5) the role of Weyl symmetry and scale invariance in the gravitation theories. The review is aimed at specialists as well as at nonspecialists in the subject, including postgraduate students.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

Assessment of recreational use of specially protected natural territories of Tatishchevsky district of Saratov region

2019 ◽  
Vol 27 (2) ◽  
pp. 117-127
Author(s):  
Yulia M Andriyanova ◽  
Irina V Sergeeva ◽  
Yulia M Mokhonko ◽  
Natalia N Gusakova
Keyword(s):  
Natural Resources ◽  
Protected Areas ◽  
Saratov Region ◽  
Future State ◽  
Forest Phytocenoses ◽  
Long Time ◽  
Main Components ◽  
First Time ◽  
Recreational Use ◽  
Specially Protected Natural Territories

The influence of recreation being a set of measures to restore health and recreation, on the main components of forest phytocenoses in specially protected natural territories of the Tatishchevsky district of the Saratov region has been studied for the first time. These phytocenoses have been intensively used for tourism for a long time. The intensity and visits activity of protected areas has been determined; the recreational capacity of territorial objects has been studied. The degree of forest landscapes has been revealed in specially protected natural territories. The findings allow predicting the future state of the natural resources of the Saratov region and can be taken into account when assessing their optimal use.

scholarly journals 6d (2, 0) and M-theory at 1-loop

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Luis F. Alday ◽  
Shai M. Chester ◽  
Himanshu Raj
Keyword(s):  
Flat Space ◽  
Lagrangian Description ◽  
Loop Correction ◽  
Higher Derivative ◽  
Weakly Coupled ◽  
S Matrix ◽  
Space Limit ◽  
Tensor Multiplet ◽  
First Time ◽  
M Theory

Abstract We study the stress tensor multiplet four-point function in the 6d maximally supersymmetric (2, 0) AN−1 and DN theories, which have no Lagrangian description, but in the large N limit are holographically dual to weakly coupled M-theory on AdS7× S4 and AdS7× S4/ℤ2, respectively. We use the analytic bootstrap to compute the 1-loop correction to this holographic correlator coming from Witten diagrams with supergravity R and the first higher derivative correction R4 vertices, which is the first 1-loop correction computed for a non-Lagrangian theory. We then take the flat space limit and find precise agreement with the corresponding terms in the 11d M-theory S-matrix, some of which we compute for the first time using two-particle unitarity cuts.

scholarly journals Clinical significance of late diastolic tissue doppler parameters after onset of STEMI: from the view point of the timing of the echocardipography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
N Iwahashi ◽  
J Kirigaya ◽  
M Horii ◽  
T Abe ◽  
E Akiyama ◽  
...  
Keyword(s):  
Tissue Doppler ◽  
Atrial Function ◽  
Diastolic Velocity ◽  
Long Time ◽  
Group A ◽  
St Elevation ◽  
Group B ◽  
First Time

Abstract Background The early transmitral flow velocity (E) divided by the early diastolic velocity of the mitral valve annulus (e') is referred to as the “E/e' ratio,” is useful even for ST elevation acute myocardial infarction (STEMI). However, the role of late diastolic velocity (a') which reveals the atrial function for STEMI is still unclear. Objectives We evaluated the clinical usefulness of tissue Doppler including atrial function for a first-time STEMI by long time follow up. Furthermore, we evaluated the meaning of each parameters by performing immediately after PCI or 2 weeks later. Methods We treated consecutive 571 first-time STEMI patients by immediate PCI within 12 hours after onset, and we examined 270 patients at immediately after PCI (GroupA, 65 years, 250 male) and 301 patients at 2 weeks after onset (GroupB, 64 years, 243 male). We examined trans mitral flow and TDI, then defined E/e' as LV filling pressure and A/a' as left atrial function. We followed them for a long time (>5 years). The primary end point (PE) was cardiac death or re-admission for heart failure (HF). Results We followed the patients in Group A for 10 years, Group B for 5 years. PE occurred in 64 patients in GroupA during 10 years, and 45 patients in GroupB during 5 years. We analyzed the univariate and multivariate Cox hazard analyses and we compared e' and a', E/e' and A/a' (Table). In GroupA, a' and A/a' were the independent predictors, on the other hand neither a' nor A/a' were the predictors in GroupB. E/e' was an independent predictor both in GroupA and B. Conclusion TDI parameters have different meanings by the timing of echocardiography after onset of a first-time STEMI. These results demonstrated that atrial dysfunction immediately after onset of STEMI suggests the poor prognosis after STEMI. Cox Hazard Proportional Analysis Funding Acknowledgement Type of funding source: None

Catalytic activity of palladium-doped silver dilute nanoalloys for formate oxidation from a theoretical perspective

2019 ◽  
Vol 21 (40) ◽  
pp. 22598-22610 ◽  
Author(s):  
Nan Zhang ◽  
Fuyi Chen ◽  
Longfei Guo
Keyword(s):  
Catalytic Activity ◽  
Oxidation Reaction ◽  
Theoretical Perspective ◽  
Single Atom ◽  
High Catalytic Activity ◽  
Formate Oxidation ◽  
First Time ◽  
Single Atom Alloys

We demonstrate for the first time that the Pd1Ag single-atom alloys exhibit a high catalytic activity for formate oxidation reaction.

scholarly journals Patients' anxiety before cardiac catheterization

2010 ◽  
Vol 8 (4) ◽  
pp. 483-487 ◽  
Author(s):  
Leandro Loureiro Buzatto ◽  
Suely Sueko Viski Zanei
Keyword(s):  
Cardiac Catheterization ◽  
Patient Information ◽  
Scientific Publications ◽  
Patient Understanding ◽  
Post Procedure ◽  
Long Time ◽  
On Line ◽  
First Time ◽  
Multiprofessional Approach ◽  
Pharmacologic Therapies

ABSTRACT Objective: To identify researches related to anxiety and strategies to reduce it in patients who are in the pre-cardiac catheterization period. Methods: A bibliographic research was carried out in the on line databases of PubMed, MedLine, CINAHL, LILACS and SciELO, from 1997 to 2009 in MedLine and from 1999 to 2009 in the others databases. The boolean expressions “and” and “or” has been used with the descriptors in Portuguese and in English. The inclusion of discerning was related about the presence, level and workable of the anxiety from the period of pre-cardiac catheterization. Results: Coping most of 17 researches selected were in American scientific publications, with experimental-descriptive studies. The possibilities of intercurrence and/or complications during and post-procedure, diagnostic, possibility of bad prognostic, being alone during the waiting, the first time submission the procedure, lost information and/or orientation and long time waiting could cause anxiety in pre-cardiac catheterization. Maintenance of escort and family alongside the patient, information adapted to the patient understanding level, overcoming traumas and difficulties with a multiprofessional approach, pharmacologic and non pharmacologic therapies were strategies to reduce the anxiety. Conclusions: The nurses are responsible to provide a humanized assistance to offer a fast recuperation, minimize traumas of the hospitalization and the procedure. The knowledge of the causes and the strategies are fundamental to reduce the level of anxiety in pre-catheterization cardiac.

scholarly journals First Results from Insemination With Sex-Sorted Semen in Dairy Heifers in Macedonia

2015 ◽  
Vol 38 (1) ◽  
pp. 107-111
Author(s):  
Ljupche Kochoski ◽  
Zoran Filipov ◽  
Ilcho Joshevski ◽  
Stevche Ilievski ◽  
Filip Davkov
Keyword(s):  
Pregnancy Rate ◽  
Transrectal Ultrasound ◽  
Gestation Length ◽  
Dairy Heifers ◽  
Holstein Friesian ◽  
First Results ◽  
Long Time ◽  
The Usa ◽  
Normal Gestation ◽  
First Time

Abstract Science has been searching for a long time for a reliable method for controlling the sex of mammalian offspring. Recently, the application of specific modern cellular methodologies has led to the development of a flow cytometric system capable of differentiating and separating living X- and Y-chromosome-bearing sperm cells in amounts suitable for AI and therefore, commercialization of this sexing technology. The aim of this work was to present the first results of heifers that introduce bovine AI with sex sorted semen, for the first time in Macedonia. Insemination with sex sorted cryopreserved semen (2×106 spermatozoa per dose) imported from the USA was done at two dairy farms in ZK Pelagonija. In total, 74 heifers (Holstein Friesian) were inseminated. Inseminations were carried out in a timely manner following a modified OvSynch protocol. During the insemination, the sperm was deposited into the uterine horn ipsi lateral to the ovary where a follicle larger than 1.6 cm was detected by means of transrectal ultrasound examination. Pregnancy was checked by ultrasound on day 30 after the insemination. Overall, the average pregnancy rate in both farms was 43,24% (40,54% and 45,95%, for farm 1 and farm 2, respectively). All pregnant heifers delivered their calves following a normal gestation length (274,3 days in average) and of the 32 born calves, 30 (93,75%) were female. In conclusion, since the first results from inseminations with sex-sorted semen in dairy heifers in Macedonia are very promising, the introduction of this technique may bring much benefit to the local dairy sector. Average pregnancy rate seems similar with results obtained following ‘regular’ inseminations, notwithstanding the relatively low number of spermatozoa per insemination dose. Due to the latter, we however recommend inseminations only to be carried out by experienced technicians followinga TAI protocol and ultrasound examinations of the ovaries prior to insemination.

scholarly journals The War of Khalkhin Gol in 1939 and the German-Soviet Nonaggression Pact

2018 ◽  
Vol 28 (4) ◽  
pp. 585-594 ◽  
Author(s):  
Alexander Sukhodolov ◽  
Tuvd Dorj ◽  
Yuriy Kuzmin ◽  
Mikhail Rachkov
Keyword(s):  
Foreign Policy ◽  
Second World War ◽  
Historical Science ◽  
World War ◽  
The World ◽  
Long Time ◽  
History Of ◽  
First Time ◽  
Further Development ◽  
Second World

For the first time in Russian historiography, the article draws attention to the connection of the War of Khalkhin Gol in 1939 and the conclusion of the German-Soviet Nonaggression Pact of 1939. For a long time, historical science considered these two major events in the history of the USSR and history of the world individually, without their historic relationship. The authors made an attempt to provide evidence of this relationship, showing the role that surrounding and defeating the Japanese army at Khalkhin Gol in August 1939 and signing in Moscow of the German-Soviet Nonaggression Pact played in the history of the world. The study analyzes the foreign policy of the USSR in Europe, the reasons for the failure in the conclusion of the Anglo-Franco-Soviet military union in 1939 and the circumstances of the Pact. It shows the interrelation between the defeat of the Japanese troops at Khalkhin Gol and the need for the Soviet-German treaty. The authors describe the historic consequences of the conclusion of the pact for the further development of the Japanese-German relations and the course of the Second World War. They also present the characteristics of the views of these historical events in the Russian historiography.

scholarly journals Quantization of Einstein-aether scalar field cosmology

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
N. Dimakis ◽  
T. Pailas ◽  
A. Paliathanasis ◽  
G. Leon ◽  
Petros A. Terzis ◽  
...  
Keyword(s):  
Scalar Field ◽  
Classical Solution ◽  
Potential Function ◽  
Scalar Fields ◽  
Inflationary Model ◽  
Cosmological Theory ◽  
Local Functions ◽  
Arbitrary Potential ◽  
Scalar Field Cosmology ◽  
First Time

AbstractWe present, for the first time, the quantization process for the Einstein-aether scalar field cosmology. We consider a cosmological theory proposed as a Lorentz violating inflationary model, where the aether and scalar fields interact through the assumption that the aether action constants are ultra-local functions of the scalar field. For this specific theory there is a valid minisuperspace description which we use to quantize. For a particular relation between the two free functions entering the reduced Lagrangian the solution to the Wheeler–DeWitt equation as also the generic classical solution are presented for any given arbitrary potential function.

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