137,678 research outputs found
Comparing shapes of engel curves
Full text linkWe measure how different the shapes of Engel curves are across 59 commodity groups. The same analysis is carried out for their derivatives and variances. While Engel curves possess a relatively homogeneous shape, significantly more heterogeneity is present in derivatives and when particular sub-classes of income are considered.Consumption, Kernel smoothing, Rank correlation, Curve shape
Nesagapostemon Engel 2009, gen. n.
No full text<i>Nesagapostemon</i> Engel, gen. n. <p>urn:lsid:zoobank.org:act: CAFD1CF7-3C12-45CE-A3F8-CBC6F3E4C392</p>Published as part of <i>Engel, Michael, 2009, Two New Halictine Bees in Miocene Amber from the Dominican Republic (Hymenoptera, Halictidae), pp. 1-12 in ZooKeys 29 (29)</i> on page 6, DOI: 10.3897/zookeys.29.257, <a href="http://zenodo.org/record/576571">http://zenodo.org/record/576571</a>
Nonparametric IV estimation of shape-invariant Engel curves
Full text linkThis paper concerns the identification and estimation of a shape-invariant Engel
curve system with endogenous total expenditure. The shape-invariant specification
involves a common shift parameter for each demographic group in a pooled
system of Engel curves. Our focus is on the identification and estimation of both
the nonparametric shape of the Engel curve and the parametric specification of the
demographic scaling parameters. We present a new identification condition, closely
related to the concept of bounded completeness in statistics. The estimation procedure
applies the sieve minimum distance estimation of conditional moment restrictions
allowing for endogeneity. We establish a new root mean squared convergence
rate for the nonparametric IV regression when the endogenous regressor has unbounded
support. Root-n asymptotic normality and semiparametric efficiency of
the parametric components are also given under a set of ‘low-level’ sufficient conditions.
Monte Carlo simulations shed lights on the choice of smoothing parameters
and demonstrate that the sieve IV estimator performs well. An application is made
to the estimation of Engel curves using the UK Family Expenditure Survey and
shows the importance of adjusting for endogeneity in terms of both the curvature
and demographic parameters of systems of Engel curves
Nonparametric IV estimation of shape-invariant Engel curves
Full text linkThis paper concerns the identification and estimation of a shape-invariant Engel curve system with endogenous total expenditure. The shape-invariant specification involves a common shift parameter for each demographic group in a pooled system of Engel curves. Our focus is on the identification and estimation of both the nonparametric shape of the Engel curve and the parametric specification of the demographic scaling parameters. We present a new identification condition, closely related to the concept of bounded completeness in statistics. The estimation procedure applies the sieve minimum distance estimation of conditional moment restrictions allowing for endogeneity. We establish a new root mean squared convergence rate for the nonparametric IV regression when the endogenous regressor has unbounded support. Root-n asymptotic normality and semiparametric efficiency of the parametric components are also given under a set of Ѭow-level' sufficient conditions. Monte Carlo simulations shed lights on the choice of smoothing parameters and demonstrate that the sieve IV estimator performs well. An application is made to the estimation of Engel curves using the UK Family Expenditure Survey and shows the importance of adjusting for endogeneity in terms of both the curvature and demographic parameters of systems of Engel curves.
DEMAND SYSTEM CHOICE BASED ON TESTING THE ENGEL CURVE SPECIFICATION
Full text linkIt is common to use a demand systems approach in estimating the key parameters from household consumption data. In conducting these studies the researcher is faced with selecting a functional form. In turn, each functional form implies a particular shape for the Engel curves. This analysis highlights the importance of testing the shape of Engel curves, especially if the researcher is interested in elasticity estimates well away from the sample mean. Using consumption data for selected households in Italy it is shown that many popular functional forms are rejected by the data.Demand and Price Analysis,
An Engel Curve Analysis of Household Expenditure in Taiwan: 1996-98
Full text linkSeven systems of Engel curves for expenditures on ten commodity groups were estimated using Taiwanese household expenditure data for the period from 1996 through 1998. Results show that the estimated expenditure elasticities are insensitive to the choice of functional forms.Engel curve, Taiwan, Consumer/Household Economics,
Engel structures on complex surfaces
Full text linkWe classify complex surfaces (M,J) admitting Engel structures D which are complex line bundles. Namely, we prove that this happens if and only if (M,J) has trivial Chern classes. We construct examples of such Engel structures by adapting a construction due to Geiges [7]. We also study associated Engel defining forms and define a unique splitting of TM associated with D J-Engel
Ischnomelissa Engel 1997
No full textKey to the Species of Ischnomelissa Females remain unknown for I. ecuadoriana, while males are unknown for I. rhina, I. cyanea, I. rasmusseni, and I. lignopteryx. 1. Females......................................................................................................................... 2 ―. Males............................................................................................................................. 7 2(1). Malar space as long as or longer than basal width of mandible.......................... 3 ―. Malar space shorter than basal width of mandible............................................. 6 3(2). Head and mesosoma dark to metallic green with copper highlights.................. 4 ―. Head and mesosoma dark metallic blue (Ecuador: Pichincha Province)........................................................................................................... I. lescheni Brooks & Engel 4(3). Metasoma and legs dark brown except sometimes with some amber coloration basally on first metasomal tergum............................................................... 5 ―. Metasoma with first tergum and most of second tergum amber, remainder of metasoma brown, legs with tarsi, tibiae, and femoral apices amber, remainder of legs brown (Ecuador: Napo and Sucumbios Provinces)... I. rhina Brooks & Engel 5(4). Metasomal terga entirely dark brown, with well-developed and distinct basal bands of yellow tomentum; wing membrane hyaline and clear; head and mesosoma distinctly dark metallic green and shining; inner metatibial spur with 17 branches, not including apical portion of rachis (Ecuador: Loja Province)............................................................................. I. rasmusseni Engel & Brooks ―. Metasomal terga dark brown except basally amber on first tergum (Fig. 1), tergal graduli without bands of tomentum; wing membrane strongly infumate (Fig. 1); head and mesosoma dark green, not shining (Figs. 1–3); inner metatibial spur with 12 branches, not including apical portion of rachis (Peru: Amazonas Department)........................................................... I. lignopteryx Engel, n. sp. 6(2). Integument of head and mesosoma dark metallic blue; T1–2 dark brown; inner metatibial spur with 12 branches, not including apical portion of rachis (Colombia: Nariño Department)..................................... I. cyanea Brooks & Engel ―. Integument of head and mesosoma non-metallic, dark brown; T1 and most of T2 amber; inner metatibial spur with 15–20 branches, not including apical portion of rachis (Colombia: Huila and Valle del Cauca Departments)... I. zonata Engel 7(1). Malar space almost as long as wide to slightly longer than wide........................ 8 ―. Malar space linear, much shorter than wide (Colombia: Huila and Valle del Cauca Departments)........................................................................... I. zonata Engel 8(7). First flagellomere one-half length of second flagellomere; mandible, malar space, and scape at least anteriorly pale; malar space slightly shorter than wide (Ecuador: Pichincha Province)................................... I. lescheni Brooks & Engel ―. First flagellomere one-fourth length of second flagellomere; mandible, malar space, and scape dark brown to black; malar space slightly longer than wide (Ecuador: Imbabura Province).............................. I. ecuadoriana Brooks & EngelPublished as part of Engel, Michael S., 2013, The bee genus Ischnomelissa in Peru, with a key to the species (Hymenoptera: Halictidae), pp. 1-5 in Journal of Melitology 2013 (23) on pages 4-5, DOI: 10.17161/jom.v0i23.4641, http://zenodo.org/record/813204
Nesagapostemon moronei Engel 2009, sp. n.
No full text<i>Nesagapostemon moronei</i> Engel, sp. n. <p>urn:lsid:zoobank.org:act: 40ED15E4-965F-40D9-8E5C-BE42E23CB1E8</p> <p>Figs 3–4</p> <p> <b>Holotype.</b> ♀, MACT-1172 (Fig. 3); amber from the Dominican Republic (specific mine unknown), Early Miocene (Burdigalian); Morone Amber Collection, Turin, Italy. The holotype is preserved with three <i>P</i>. <i>dominicana</i> workers, one alongside the holotype’s metasoma and one at each end of the piece, as well as several small flies. The holotype is not well preserved, with the several fractures around the metasoma, which</p> <p> <b>Figures 3–4.</b> Photomicrographs of holotype female of <i>Nesagapostemon moronei</i> <b>gen. n. sp. n.</b> (MACT- 1172) <b>3</b> Dorsal aspect of holotype <b>4</b> Detail of extended (right) metatibia and metatarsus.</p> <p>itself is curved under the remainder of the body, and much of the bee is covered in minute air pockets, fractures, and some orangish debris such that glimpses onto the integument are challenging, but possible.</p> <p> <b>Diagnosis.</b> As for the genus (<i>vide supra</i>).</p> <p> <b>Description.</b> As for the genus with the following additions: <i>Female</i>: Total body length 9.9 mm; forewing length 6.9 mm. Head width 2.4 mm; apparently wider than long although a direct frontal view of the face is not possible in the holotype. Forew- ing with basal vein strongly arched, distad cu-a by 1.5 times vein width; 1rs-m distad 1m-cu by about three times vein width; 2rs-m gently arcuate, distad 2m-cu by about six times vein width; first submarginal cell longer than combined lengths of second and third submarginal cells; second submarginal cell relatively square, length of anterior border of second submarginal cell along Rs as long as abscissa of Rs forming its proximal border and about as long as r-rs, slightly shorter than anterior border of third submarginal cell; anterior border of third submarginal cell along Rs about two-thirds length of posterior border. Inner metatibial spur with three branches (not including apical portion of rachis).</p> <p>Sculpturing of head and mesosoma apparently with coarse punctures separated by less than a puncture width, integument between apparently smooth and shining, those punctures of mesosoma larger than those of head. Metasomal terga granulose with coarse, shallow punctures separated by a puncture width or less (owing to preservation best seen laterally in holotype when viewed from above as metasoma is slightly twisted exposing the terga; in ventral aspect the central portions of the terga are largely covered with fine debris); apical margins of terga apparently impunctate and strongly imbricate; metasomal sterna not easily visible.</p> <p>Integumental coloration obscured by layers of air in most places giving a silvery reflection. In places where integument is more easily seen (small places on face, vertex, gena, metasoma laterally, and some of the sterna) apparently head and mesosoma metallic except antenna dark brown and tegula translucent brown, while metasomal terga dark brown with weaker metallic green highlights, sterna dark brown without highlights. Wing membranes hyaline; veins brown. Legs dark reddish brown.</p> <p> <b>Etymology.</b> The specific epithet is a patronymic honoring Dott. Ettore Morone in recognition for his support of my studies and his many generous kindnesses.</p> <p> <b>Provisional Key to the Dominican Amber Halictidae</b></p> <p>The following provisional key is based on females only as the male of <i>E</i>. <i>dominicana</i> is the only halictine male presently documented from Dominican amber.</p> <p>1. Pseudopygidial area without medioapical slit; posterior surface of propodeum encircled by strong carinae (Caenohalictini)............................................... <b>2</b></p> <p>– Pseudopygidial area with medioapical slit; posterior surface of propodeum not encircled by strong carinae (Augochlorini)........................................... <b>3</b></p> <p>2. Small species (length about 5 mm); basal area of propodeum slanting in profile, as long as vertical posterior surface; metatibia with scattered moderatelength setae, setae with a few apical branches, those on inner surface distinctly longer than those on outer surface; apex of rachis of inner metatibial spur not hooked; marginal cell apex sharply pointed on anterior wing margin, inner border on costa 1.4–1.6 times length of pterostigma.............................................................................. <b> <i>Eickwortapis dominicana</i> Michener & Poinar</b> </p> <p>– Large species (length about 9.9 mm); basal area of propodeum not slanting in profile, about one-half length of vertical posterior surface; metatibia densely setose, setae on inner surface elongate, longer than metatibial spurs, intermingled with long plumose setae and more elongate simple setae, setae on outer surface about as long as those on inner surface and plumose [cf. Fig. 4 with figure 6 of Michener and Poinar (1996)]; apex of rachis of inner metatibial spur hooked; marginal cell apex acutely rounded on anterior wing margin, inner border on costa 2 times length of pterostigma.............................................................................. <b> <i>Nesagapostemon moronei</i> gen. n. sp. n.</b> </p> <p>3. Epistomal sulcus outside of subantennal sulci forming obtuse angle; inner metatibial spur pectinate............................................................................ <b>4</b></p> <p>– Epistomal sulcus outside of subantennal sulci forming small, acute angle; inner metatibial spur simple, serrate.................... <b> <i>Augochlora leptoloba</i> Engel</b> </p> <p>4. Anterior border of mesoscutum broadly and gently rounded, not projecting over pronotum........................................................................................... <b>5</b></p> <p>– Anterior border of mesoscutum narrowed medially and projecting over pronotum................................................................ <b> <i>Neocorynura electra</i> Engel</b> </p> <p>5. Basal area of propodeum dull and granular or imbricate, with or without short basal striae, never smooth, polished, and shining............................... <b>6</b></p> <p>– Basal area of propodeum smooth and shining, without striae................................................................................................... <b> <i>Oligochlora eickworti</i> Engel</b> </p> <p>6. Basal area of propodeum without minute basal striae................................. <b>7</b></p> <p>– Basal area of propodeum with minute basal striae...................................... <b>9</b></p> <p>7. Pronotal dorsolateral angle orthogonal; basal area of propodeum granular..... <b>8</b></p> <p>– Pronotal dorsolateral angle obtuse; basal area of propodeum imbricate................................................. <b> <i>Oligochlora marquettorum</i> Engel & Rightmyer</b> </p> <p>8. Smaller species (total body length under 7.5 mm); inner metatibial spur with three branches (not including apical portion of rachis)........................................................................................................ <b> <i>Oligochlora grimaldii</i> Engel</b> </p> <p>– Larger species (total body length over 8 mm); inner metatibial spur with four branches (not including apical portion of rachis)..... <b> <i>Oligochlora rozeni</i> Engel</b> </p> <p>9. Pronotal dorsolateral angle orthogonal; gena granular, without rugae; mesoscutum granular and largely impunctate....... <b> <i>Oligochlora micheneri</i> Engel</b> </p> <p>– Pronotal dorsolateral angle obtuse; gena granular and transversely rugulose; mesoscutum granular with contiguous punctures except punctures more widely spaced medially.................................. <b> <i>Oligochlora semirugosa</i> sp. n.</b> </p>Published as part of <i>Engel, Michael, 2009, Two New Halictine Bees in Miocene Amber from the Dominican Republic (Hymenoptera, Halictidae), pp. 1-12 in ZooKeys 29 (29)</i> on pages 7-10, DOI: 10.3897/zookeys.29.257, <a href="http://zenodo.org/record/576571">http://zenodo.org/record/576571</a>
Engel-type subgroups and length parameters of finite groups
No full textLet g be an element of a finite group G and let Rn(g) be the subgroup generated by all the right Engel values [g,nx] over x?G. In the case when G is soluble we prove that if, for some n, the Fitting height of Rn(g) is equal to k, then g belongs to the (k+1)th Fitting subgroup Fk+1(G). For nonsoluble G, it is proved that if, for some n, the generalized Fitting height of Rn(g) is equal to k, then g belongs to the generalized Fitting subgroup F?f(k,m)(G) with f(k,m) depending only on k and m, where |g| is the product of m primes counting multiplicities. It is also proved that if, for some n, the nonsoluble length of Rn(g) is equal to k, then g belongs to a normal subgroup whose nonsoluble length is bounded in terms of k and m. Earlier similar generalizations of Baer's theorem (which states that an Engel element of a finite group belongs to the Fitting subgroup) were obtained by the first two authors in terms of left Engel-type subgroups.</p
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