5,547 research outputs found
Large Firm Dynamics and the Business Cycle
Do large firm dynamics drive the business cycle? We answer this question by developing a quantitative theory of aggregate fluctuations caused by firm-level disturbances alone. We show that a standard heterogeneous firm dynamics setup already contains in it a theory of the business cycle, without appealing to aggregate shocks. We offer a complete analytical characterization of the law of motion of the aggregate state in this class of models – the firm size distribution – and show that the resulting closed form solutions for aggregate output and productivity dynamics display: (i) persistence, (ii) volatility and (iii) time-varying second moments. We explore the key role of moments of the firm size distribution – and, in particular, the role of large firm dynamics – in shaping aggregate fluctuations, theoretically, quantitatively and in the data
A bound on 6D N=1 supergravities
We prove that there are only finitely many distinct semi-simple gauge groups
and matter representations possible in consistent 6D chiral (1,0) supergravity
theories with one tensor multiplet. The proof relies only on features of the
low-energy theory; the consistency conditions we impose are that anomalies
should be cancelled by the Green-Schwarz mechanism, and that the kinetic terms
for all fields should be positive in some region of moduli space. This result
does not apply to the case of the non-chiral (1,1) supergravities, which are
not constrained by anomaly cancellation.Comment: 23 pages, no figures; two paragraphs added to the proof in Appendix A
covering the SU(2) and SU(3) case, other minor correction
The synergistic effect between positivity, socio-demographic factors and smoking cessation: results of a cohort study
OBJECTIVE: To examine the extent to which a effect does exist between Positivity (POS), smoking and socio-demographic factors in determining quitting smoking in subjects participating in a Group Counselling Program (GCP) for smoking cessation.METHODS: 481 subjects were contacted through a telephone call. A logistic regression analysis was carried out. Possible interaction between sociodemographic variables and POS level was tested using the Synergism Index (SI).RESULTS: For individuals with a POS level over or equal to 3.4 the odds of being smoker was significantly higher among females (OR = 1.55), who smoked at home (OR = 2.16) and lower if there had children at home (OR = 0.53). For individuals with a POS level under 3.4, the only significant variable associated with smoking was beinga female (OR = 2.58). As far concerns the synergistic effect between the variables considered does exist between POS levels and having children at home (SI=1.13) and female gender (SI = 2.8).CONCLUSIONS: The synergistic effect between POS and sociodemographic factors adds evidence on the use of POS as possible determinants of individual happiness
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Bottom-up Markup Fluctuations
We study markup cyclicality in a granular macroeconomic model with oligopolistic competition. We characterize the comovement of firm, sectoral, and economy-wide markups with sectoral and aggregate output following firm-level shocks. We then quantify the model’s ability to reproduce salient features of the cyclical properties of markups in French administrative firm-level data, from the bottom (firm) level to the aggregate level. Our model helps rationalize various, seemingly conflicting, measures of markup cyclicality in the French data
Continuous approximation of binomial lattices
A systematic analysis of a continuous version of a binomial lattice,
containing a real parameter and covering the Toda field equation as
, is carried out in the framework of group theory. The
symmetry algebra of the equation is derived. Reductions by one-dimensional and
two-dimensional subalgebras of the symmetry algebra and their corresponding
subgroups, yield notable field equations in lower dimensions whose solutions
allow to find exact solutions to the original equation. Some reduced equations
turn out to be related to potentials of physical interest, such as the
Fermi-Pasta-Ulam and the Killingbeck potentials, and others. An instanton-like
approximate solution is also obtained which reproduces the Eguchi-Hanson
instanton configuration for . Furthermore, the equation under
consideration is extended to --dimensions. A spherically symmetric form
of this equation, studied by means of the symmetry approach, provides
conformally invariant classes of field equations comprising remarkable special
cases. One of these enables us to establish a connection with the
Euclidean Yang-Mills equations, another appears in the context of Differential
Geometry in relation to the socalled Yamabe problem. All the properties of the
reduced equations are shared by the spherically symmetric generalized field
equation.Comment: 30 pages, LaTeX, no figures. Submitted to Annals of Physic
Early mandibular canine-lateral incisor transposition: case report
Purpose. The main aim of the present study is to present a case of mandibular transposition between lateral incisor and
canine in a paediatric patient.
Materials and methods. A fixed multibracket orthodontic treatment was performed by means of a modified welded arch
as to correct the transposition and obtaining a class I functional and symmetrical occlusion, also thanks to the early diagnosis
of the eruption anomaly.
Results. Our case report shows that a satisfactory treatment of mandibular transpositions is obtained when detected at
an early stage of the tooth development.
Conclusions. The main treatment options to be taken into consideration in case of a mandibular transposition are two:
correcting the transposition or aligning it leaving the dental elements in their transposed order; in both cases, the followups
show a stable condition, maintained without relapses. Several factors, such as age of the patient, occlusion, aesthetics,
patient’s collaboration, periodontal support and duration of treatment have to be considered as to prevent potential damage
to dental elements and support appliances. The choice between the two treatment approaches for mandibular lateral
incisor/canine transpositions mainly depends on the time the anomaly is detected
Cyberbullying through the lens of social influence: Predicting cyberbullying perpetration from perceived peer-norm, cyberspace regulations and ingroup processes
In the present research we analyzed the social influence mechanisms that back the relation between peer group norms regarding cyberbullying behaviors and individual cyberbullying perpetration. In a sample of adolescents (N = 3511, age: M = 16.27, SD = 1.58), we showed that the relation between perceived peer-norm and cyberbullying perpetration was moderated by two distinct social influence mechanisms. Specifically, when individuals' lack of knowledge regarding appropriate behaviors in cyberspace (i.e., cyberspace regulations), levels of perceived peer-norm regarding cyberbullying behaviors positively influence the participants' engagement in cyberbullying perpetration (i.e., informational social influence). Moreover, we showed that the higher the support of perceived peer-norm regarding cyberbullying behaviors the higher the levels of cyberbullying perpetration, especially for the higher (vs. lower) levels of identification with peers as the ingroup; this relation was additionally enhanced at increasing levels of adolescents' ingroup prototypicality (i.e., referential informative social influence). The results demonstrated that the two social influence mechanisms work independently and likely contribute to predict participants\u2019 engagement in cyberbullying perpetration. Results are discussed with respect to the current literature regarding the social influence mechanisms underlying cyberbullying. The implications of these findings for practical interventions are explored
Fluctuations of the Initial Conditions and the Continuous Emission in Hydrodynamic Description of Two-Pion Interferometry
Within hydrodynamic approach, we study the Bose-Einstein correlation of
identical pions by taking into account both event-by-event fluctuating initial
conditions and continuous pion emission during the whole development of the hot
and dense matter formed in high-energy collisions. Considerable deviations
occur, compared to the usual hydro calculations with smooth initial conditions
and a sudden freeze-out on a well defined hypersurface. Comparison with data at
RHIC shows that, despite rather rough approximation we used here, this
description can give account of the dependence of and and
improves considerably the one for with respect to the usual version.Comment: 5 pages, 4 figure
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