45,787 research outputs found
The Harris-Todaro Hypothesis
No full textThe Harris-Todaro hypothesis replaces the equality of wages by the equality of ‘expected’ wages as the basic equilibrium condition in a segmented but homogeneous labour market, and in so doing it generates an equilibrium level of urban unemployment when a mechanism for the determination of urban wages is specified. This article reviews work in which the Harris-Todaro hypothesis is embedded in canonical models of trade theory in order to investigate a variety of issues in development economics. These include the desirability (or the lack thereof) of foreign investment, the complications of an informal sector, and the presence of clearly identifiable ethnic groupsHarris-Todaro, Wages, Labour Economics, Labour Market, Rural to Urban Migration
The Harris-Todaro Hypothesis
No full textThe Harris-Todaro hypothesis replaces the equality of wages by the equality of ‘expected’ wages as the basic equilibrium condition in a segmented but homogeneous labour market, and in so doing it generates an equilibrium level of urban unemployment when a mechanism for the determination of urban wages is specified. This article reviews work in which the Harris-Todaro hypothesis is embedded in canonical models of trade theory in order to investigate a variety of issues in development economics. These include the desirability (or the lack thereof) of foreign investment, the complications of an informal sector, and the presence of clearly identifiable ethnic groups.Harris-Todaro; Wages; Labour Economics; Labour Market; Rural to Urban Migration
The Harris-Todaro Hypothesis
No full textThe Harris-Todaro hypothesis replaces the equality of wages by the equality of expected wages as the basic equilibrium condition in a segmented but homogeneous labour market, and in so doing it generates an equilibrium level of urban unemployment when a mechanism for the determination of urban wages is specified. This article reviews work in which the Harris-Todaro hypothesis is embedded in canonical models of trade theory in order to investigate a variety of issues in development economics. These include the desirability (or the lack thereof) of foreign investment, the complications of an informal sector, and the presence of clearly identifiable ethnic groups.Harris-Todaro, Wages, labour economics, Labour Market, Rural to Urban Migration
On The Removal of Agricultural Price Bands in Chile: A General Equilibrium Analysis
No full textChile has supported its agriculture with the use of price bands on selected commodities namely wheat, vegetable oils and fats, and sugar. In this paper we consider agricultural reform and how urban unemployment, and rural-urban migration, may alter the expected welfare effects of agricultural reform. We utilize a new CGE model of the Chilean economy based on the Harris-Todaro ramework, incorporating imperfect labor mobility, and consider both price band removal and more extensive agricultural reform that eliminates all tariffs on agricultural and food commodities in Chile. Results show that if trade reforms damage the rural economy in Chile, potential gains in welfare from lower agricultural prices are offset by increased urban unemployment and lower rural wages resulting in net welfare loss from trade reform.
Lectio magistralis: Bernard Lassus. Per una demarche globale? Il paesaggio
No full textIntervento di presentazine dell'opera di Bernard lassus, in occasione della Lectio Magistralis di B. Lassus e della pubblicazione del volume di P. Capone, "Il restauro impossibile. Un progetto di Bernard Lassus per il Cilento", 2012. Organizzato dalla Facoltà di Architettura di Roma in collaborazione con il Dipartimento di Scienze Politiche Sociali e della Comunicazione dell'Università di Salerno
Emigration promotion and urban unemployment
No full textUnemployment is present in many developing countries. Thus, the government of a country that suffers from chronic unemployment often wants to emigrate some workers to foreign countries. This paper investigates whether such a policy is successful for reducing domestic unemployment.Unemployment; Emigration; Harris-Todaro model
Transfer of Pollution Abatement Technology and Unemployment
No full textThis paper investigates the effects of the transfer of pollution abatement technology on the level of urban unemployment, the total amount of pollution, and social welfare in a small, open Harris Todaro economy. We show that these transfers reduce urban unemployment and decrease the total amount of pollution. However, social welfare is unchanged because the technology transfer does not affect factor prices.
Tetranchyroderma hyponiglarum Hummon & Todaro, 2009, new species
No full text<i>Tetranchyroderma hyponiglarum</i> new species [Tet hpng] <p>Figure 5 A–C</p> <p> <i>Tetranchyroderma</i> sp. AC (Todaro, Hummon, Balsamo, Fregni & Tongiorgi 2001: p. 128); (Hummon 2001 – 2009: W Med Database)</p> <p> <b>Diagnosis:</b> Adult Lt 504 Μm; PhJIn at U28. Head end rounded, without tentacles or sensorial knobs; body narrowest at the PhJIn, broadest in the anal region, then narrowing to the broad caudal base; caudal pedicles medium, with a concave medial border indenting to U95. Epidermis fully covered with small tetrancres. Glands small, 16 per side, with a cluster of 8 in the rump region. TbA 4 per side, form a stepped transverse row, tubes inserting directly on the body, the most medial separated from the 3 more lateral by a small gap; TbL 13 per side, 1 in the fore pharyngeal region, the others regularly spaced and of similar size occur along the intestine at U31- U85, with 2 inserting behind the anus; TbV occur as a solitary tube or a fan of 3 tubes with a common base; TbD absent; TbP 3 per side on the caudal pedicles, forming the fused ‘two fingers and a thumb’ typical of the family, with a cirratum-like element inserting between the ‘fingers’, with 3 more tubes in the interpeduncular space (total 5). Locomotor ciliature: a single field covers the ventral body surface. Mouth subterminal, narrower than the fore end of the body, oral hood reaches only to U02; buccal cavity non-cuticularized; pharynx has basal pharyngeal pores; intestine broadest in the middle, narrowing to the rear; anus at U91. Testis is on left as seen from below; vas deferens opens into the rear of the bibulbed caudal organ in front of the anus; developing egg occurs in the rear mid-gut region; round frontal organ bears small spheres, and was without sperm.</p> <p> <b>Description:</b> Adult Lt 504 Μm; LPh 140 Μm to PhJIn at U28 (Fig. 5 A, B). Body elongate as an adult, ventrally flattened, dorsally vaulted; head end rounded, without tentacles or sensorial knobs; trunk narrows in the PhJIn region, broadens gradually to the anal region, then narrows to the broad caudal base; caudal pedicles medium (L 25 Μm) naked, with a concave margin separating the two groups, indenting medially to U95. Widths behind mouth/PhJIn/midgut/anus/caudal base and locations along the length of the body are as follows: 42/38/ 51/59/48 Μm at U04/U28/U60/U85/U97, respectively. Glands 16 per side (5–10 Μm diam.) are scattered along the sides in lateral and dorsal columns, with a cluster of 8 lying just before the caudal base.</p> <p> <b>Cuticular Armature:</b> Small tetrancres fully cover the dorsal, lateral and ventrolateral epidermis; ancres (Fig. 5 C; W 2–3 Μm, H 3–5 Μm) are smaller in the fore body than in the mid- and hindbody. They are absent from the oral hood and caudum.</p> <p> <b>Adhesive tubes:</b> TbA 4 per side (L 10–12 Μm), forming a stepped transverse row, the tubes inserting directly on the postoral body surface at U03-U04, the most medial occurring behind the others and pointing forward, and after a small separation the 3 more lateral pointing obliquely forward; TbL 13 per side (L 12–26 Μm), with 1 in the fore pharyngeal region at U10, none in the hind pharyngeal region, 10 of varying size and irregular spacing in the intestinal region at U31-U85, and 2 inserting behind the anus; TbV occur as a solitary tube or a fan of 3 tubes with a common base (L 18–24 Μm) at U78; TbD are absent; TbP 3 per side on the caudal pedicles, forming the fused ‘two fingers and a thumb’ typical of the family, (L terminal tubes 10–11 Μm, L tube on the inner margin also 10 Μm), with a cirratum-like element inserting between the ‘fingers,’ and with 3 additional tubes in the interpedicular space for a total of 5.</p> <p> <b>Ciliation:</b> Short sensory cilia (L 4 Μm) surround the entire oral opening, with longer vibratile cilia (L 16– 18 Μm) on each side of the oral hood; other hairs (L 14 Μm) occur regularly along the lateral body surfaces, numbering 28–30 per side; other columns have not been seen. Ventral locomotor ciliature forms a single field of transverse rows beneath the body, extending from U04 to the anus at U92; individual cilia are 10–12 Μm in length.</p> <p> <b>Digestive tract:</b> Mouth subterminal, narrower than the fore end of the body, width 15 Μm, the oral hood extending from its tip 10 Μm rearward to U02; non-cuticularized buccal cavity narrows quickly; pharynx has basal pharyngeal pores at U25; intestine is broadest in the mid-body, narrowing gradually to the rear; anus is at U91.</p> <p> <b>Reproductive tract:</b> Testis is on the left side as seen from below; vas deferens opens into the rear of the caudal organ near the anus; a developing egg occurs in the mid-gut region on the opposite side (largest 25 x 41 Μm); bibulbous caudal organ (ca. 16 x 40 Μm), with a hollow fore bulb, lies in front of the anus; frontal organ is a round cluster (ca. 20 Μm diam.) of spheres (3 Μm diam.), no sperm being seen.</p> <p> <b>Ecology:</b> Sparse in frequency of occurrence (less than 10% of samples), rare in abundance (less than 1% of a sample); <i>sublittoral</i> in fine, medium-well sorted sand at 1.5–5.0 m water depth.</p> <p> <b>Geographical distribution: MED: EUROPE:</b> <i>ITALY</i>: <i>Campania Archipelago</i> {Isola d’Ischia: Spiaggia degli Inglesi, Spiaggia d'Ischia Porto^ 40°,45’N/13°,56’E [video]}</p> <p> <b>Remarks</b>: The description of <i>Tetranchyroderma hyponiglarum</i> <b>n. sp.</b> is taken from a single specimen, one of only two found, (WDH video #1521, a holotype, ICZN Article 73.1.2). <i>T. hyponiglarum</i> <b>n. sp.</b> is unusual among macrodasyids in being broader in the rear body than in the fore body.</p> <p> <b>Etymology:</b> The species is named for the adhesive tubes that lie beneath the trunk (Greek: <i>hypo</i>) under, beneath (Greek: <i>niglaros</i>) small pipe, whistle.</p> <p> <b>Taxonomic affinities:</b> <i>Tetranchyroderma hyponiglarum</i> <b>n. sp.</b> and the two species to be described below bring the total in this genus into the upper-60s. With this species, there are 4 that are tetrancrous and have TbV, only 3 of which have been described (Todaro 2002: key to species in the genus, p. 561). <i>T. hyponiglarum</i> alone has but one group of TbV, fewer than 15 TbL per side with 1 in the fore pharyngeal and 0 in the rear pharyngeal regions, and only 4 TbA per side. <i>T.</i> sp. 5 of Valbonesi & Luporini (1984: p. 20, Fig. 9) is closest in overall body shape, being broadest in the rear, but has 0 of 11 TbL in the fore pharyngeal and 3 in the rear pharyngeal regions, while it has 7 TbA per side.</p>Published as part of <i>Hummon, William D. & Todaro, Antonio, 2009, Italian marine Gastrotricha: VI. Seven new species of Macrodasyida, pp. 47-68 in Zootaxa 2278</i> on pages 59-61, DOI: <a href="http://zenodo.org/record/191139">10.5281/zenodo.191139</a>
Study of the decay mechanism for B+ -> p(p)over-barK(+) and B+ -> p(p)over-bar pi(+)
No full textWe study the characteristics of the low mass p (p) over bar enhancements near threshold in the three-body decays B+ -> p (p) over barK(+) and B+ -> p (p) over bar pi(+). We observe that the proton polar angle distributions in the p (p) over bar helicity frame in the two decays have the opposite polarity, and measure the forward-backward asymmetries as a function of the p mass for the p (p) over barK(+) mode. We also search for the intermediate two-body decays, B+ -> (p) over bar Delta(++) and B+ -> p (Delta) over bar (0), and set upper limits on their branching fractions. These results are obtained from a 414 fb(-1) data sample that contains 449 x 10(6) B (B) over bar events collected near the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. (c) 2007 Elsevier B.V. All rights reserved.IPE
Pseudostomella mandela Todaro, Perissinotto & Bownes, 2015, n. sp.
No full textPseudostomella mandela n. sp. Figs. 6–9 ZooBank lsid:zoobank.org:act:C 8 FA 4 EBD- 5939 - 4 F 79 -AD 7 F- 4 CB02FE 184 CA Type locality. South Africa, KwaZulu-Natal, Cape Vidal, iSimangaliso Wetland Park (Latitude 28 °07’ 18 ” S; Longitude 32 ° 33 ’ 43 ” W); at about 1.5 m water depth, in fine to medium, well sorted sand (mean grain size, 0.246 mm; sorting, 0.46). Values of salinity and pH of coastal waters around the time of sampling were 36.8 and 8.4, respectively, with temperatures ranging from 27–28 ° C. Other locations. Umhlanga (Durban) at 5 m water depth in fine, moderately well sorted siliceous sands (mean grain size, 0.228 mm sorting, 0.51); St. Lucia beach, at mid-tide level in medium-sized, moderately sorted, siliceous grains on a high-energy sandy beach (see Todaro et al. 2011 b). Type specimens. Holotype: the 477 Μm long adult specimen shown in Figure 7, no longer extant (International Code of Zoological Nomenclature, Articles 73.1. 1 and 73.1.4), collected on 2 February 2013 (MAT legit). Additional material examined. Five adult specimens, four collected by the author from the type locality and one from Umhlanga, all were observed alive and are no longer extant. Three further identified specimens were fixed in alcohol and are kept in the collection of the first author. Ecology. Frequency of occurrence: common in sediment along the ocean shore of the iSimangaliso Wetland Park, usual in southern sites near Durban. Abundance: prevalent to numerous in sub-littoral sediment at 1.5 m, scarce in deeper and littoral sediments where found. Diagnosis. A Pseudostomella with an adult TL up to 481 µm; pharynx length up to 105 µm, with pharyngeal pores at base. PhIJ at U 33; body slender, with fine lines and elongate, furcate caudum. Head with mid-sized fleshy preoral palps curving forward; palps showing few sensory hairs and provided with 5 and 6 papillae on the dorsal and ventral border respectively. Sensory hairs sparse but evenly spaced on the body, forming two columns from about U 11 to U 89; epidermal glands barely visible, asymmetrically scattered along most of the length of the body. Cuticular armature of medium-size tetrancres on whole dorsal and ventrolateral surface. Adhesive tubes: TbA, 4 per side, a small one medially and 3 larger ones laterally, forming an arc; TbDL, 1 per side, inserting on lateral margin of the posterior trunk region at U 90; TbVL, 11 per side, of considerably variable length, irregularly spaced along the intestinal region from U 40 to U 81; the last two tubes appearing very close to each other but not sharing a common base; TbP, 4 per side, 2 + 1 at the end of each caudal pedicle the other one flanking each pedicle medially; cirrata tubes, 7 per side, 2 smaller ones inserting laterally along the pharyngeal region at U 16 and U 32 respectively, and 5 larger ones inserting dorso-laterally on the trunk from U 48 to U 87; the last one particularly large. Ventral locomotory cilia: a continuous field of transverse rows covering sparsely the entire ventral surface except the anogenital area. Reproductive system: testis on the right body side, sperm duct noticeably swollen at the confluence of the ano-genital area; caudal organ inverted, pyriform, at U 80; frontal organ, small, bladder-like, at U 77; maturing eggs mid-dorsally above the intestine. Etymology. The species is dedicated to the late Nelson Rolihlahla Mandela, the first democratically elected President of South Africa and 1993 Nobel Peace Prize awardee. Description. The description is mainly based on the adult holotype specimen, 477 µm in total length, shown in Figure 6. Body somewhat slender, a little swollen in the posterior pharyngeal region and at the base of the 44 µm long caudal pedicles. Pharynx 104 µm in length, measured from the ventral border of the oral opening to the pharyngeo-intestinal junction; pharyngeal pores near the base at U 31; pharyngeo-intestinal junction at U 33; widths of neck\PhIJ\trunk\caudal base are 45 \ 41 \ 57 \ 28 µm at U 22 \U 33 \U 51 \U 91, respectively. Head with well developed, fleshy preoral palps, curving ventromedially; the dorsal border projecting just beyond the ventral. Sensory hairs and papillae present on dorsal and ventral borders of the preoral palps; hairs are scattered on the dorsal, lateral and ventral surface of the palps; dorsally there are five papillae, nearly of the same length (5–7 µm), symmetrically arranged along the inner border of the palps in a 2 + 1 + 2 pattern; ventrally, there are six clearly recognizable papillae, 3–6 µm in length, symmetrically arranged more centrally about the inner border of the palps in a 3 + 3 pattern; all papillae bearing one or two short sensory hairs at their tip; other sensory cilia form lateral columns that are more or less evenly spaced from U 11 to U 89; individual hairs are 12–15 µm in length. A variable number of additional papillae, much smaller in size (1–3 µm), can be found ventrally along the inner border of the palps. Epidermal glands barely visible, variable in shape (oval to oblong) and size (5–8 µm in diameter), asymmetrically scattered along most of the length of the body. Cuticular armature. Mid-sized tetrancres with delicate, nearly straight lines, taller than wide (3 x 2 µm – 10 x 7 µm) on the whole dorsal and ventrolateral surface; posteriorly ancres do not extend onto the caudum. Adhesive tubes. TbA, 4 per side, a small one medially (3 µm in length) and 3 larger ones laterally (7–8 µm in length), forming an arc at U09-U 10; TbDL, 1 per side (14–16 µm in length), inserting on the lateral margin of the posterior trunk region at U 90; TbVL, 11 per side, of different size, irregularly spaced along the intestinal region from U 40 to U 81; 5 tubes are visibly larger (23–29 µm in length) and 6 are smaller (11–17 µm in length) than the others; the last two smaller tubes appear very close to each other yet they seem to originate independently, i.e. do not share a common base; TbP, 4 per side, 2 + 1 (5–6 µm in length) at the end of each pedicle of the furcated caudum and the other one (10–11 µm in length) flanking each pedicle medially. Ventral locomotory cilia. A continuous field of transverse rows covering sparsely the entire surface except around the ano-genital area at U 85. Reproductive system. Testis on the right body side, sperm duct noticeably swollen at the confluence of the anogenital area; caudal organ inverted, pyriform (35 µm long x 15 µm wide), at U 80; frontal organ, bladder-like (10–12 µm in diameter) at U 77; maturing eggs mid-dorsally above the intestine. Variability and remarks. The body length of 6 living specimens ranged from 465 to 481 µm (mean = 476.6 µm SD = 5.3 µm), all of them were mature (i.e. showed at least the testis filled with sperm). One specimen (TL = 480 µm) showed an asymmetry in the TbA by virtue of a supernumerary fifth tube on the right side (Fig. 9); the adhesive tubes of the TbVL series showed some variability in number, depending on individuals, ranging from 10 to 13 tubes; however, in all specimens the last two tubes were very close to each other with the longest of the two being the terminal one. Although the last two tubes appear to originate independently under DIC optics, a final word on this matter would necessitate a SEM survey. In a previous study, we reported on a juvenile specimen of Pseudostomella found at St Lucia beach (iSimangaliso Wetland Park, Todaro et al. 2011 b). The cuticular covering, made up of tetrancres, the rather long caudal pedicles and the same area of the finding leave no doubt that the current adult specimens and the juvenile found previously belong to the same species. This is despite some differences regarding the presence of TbL in the juvenile but not in the adults, which bear cirrata tubes instead. Cirrata tubes have been described for several thaumastodermatid species e.g., Tetranchyroderma (Todaro 2002) and are generally thought to convey the secretions (probably with a repellent function) produced by the epidermal glands externally. The densely packet droplets clearly visible inside the cirrata tubes of P. mandela n. sp. (see Fig. 7 D), resembling the epidermal droplets recently described for Ptychostomella lamelliphora Todaro, 2013 (see Todaro 2013, Fig. 4 D), seem to support this hypothesis. The reported disparities between juveniles and adults highlight the significant ontogenetic morphological variations experienced by Pseudostomella specimens during their life, and once again caution researchers on using only mature specimens for a reliable identification and/or species description. Taxonomic affinities. Within Thaumastodermatinae, the genera Tetranchyroderma and Pseudostomella, the number of prongs forming the peculiar scales called ancres, which composes the body cuticular armature, has been regarded as the single most useful taxonomic trait to classify species (e.g., Lee & Chang 2002; Todaro 2002; but see Todaro et al. 2011 a). Consequently, in the genus Pseudostomella three basic species groups are envisaged based on the type of pronged spines i.e., species characterized by triancres (3 prongs), tetrancres (4 prongs) or pentancres (5 prongs). Based on the type of ancres, Pseudostomella mandela n. sp. approaches six other species all characterized by a tetrancrous covering: P. andamanica Rao, 1993, P. indi ca Rao, 1970, P. koreana Lee & Chang, 2002, P. longifurca Lee & Chang, 2002, P. m al ay i ca Renaud-Mornant, 1967 and P. ro s c o vi t a Swedmark, 1956 (see Todaro 2012). However, based on the number of dorsal papillae (5) on the preoral palps, the new species is most similar to P. longifurca and P. indica. The number and distribution of the adhesive tubes is useful in discriminating the three taxa e.g., P. longifurca bears 5 TbA and 7 TbP per side and P. i n di c a 2 TbA and 5 TbP, in contrast with the new species that exhibits 4 TbA and 4 TbP per side. P. mandela n. sp. is further distinguished as the only species in the genus that possesses cirrata tubes (7 pairs). The finding of an additional new taxon seems to support the idea that Pseudostomella species appear to have a relatively restricted geographic range, at least compared to the wide distribution and cosmopolitan nature of many other gastrotrichs (cf. Todaro et al. 1996; Artois et al. 2011; Curini-Galletti et al. 2012; Kånneby et al. 2012; Kieneke et al. 2012).Published as part of Todaro, M. Antonio, Perissinotto, Renzo & Bownes, Sarah J., 2015, Two new marine Gastrotricha from the Indian Ocean coast of South Africa, pp. 193-208 in Zootaxa 3905 (2) on pages 200-205, DOI: 10.11646/zootaxa.3905.2.2, http://zenodo.org/record/23214
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