Spatial pattern of floral morphology: a possible insight into the effects of pollinators on plant distribution

Pollination syndromes involve convergent evolution towards phenotypes composed of specific scents, colours or floral morphologies that attract or restrict pollinator access to reward. How these traits might influence the distributions of plant species in interaction with pollinators has rarely been investigated. We sampled 870 vegetation plots in the western Swiss Alps and classified the plant species into seven blossom types according to their floral morphology (wind, disk, funnel, tube, bilabiate, head or brush). We investigated the environmental features of plots with functional diversity (FD) lower than expected by chance alone to detect potential pollination filtering and related the proportions of the seven blossom types to a combination of environmental descriptors. From these results, we inferred the potential effect of the pollinator on the spatial distribution of plant species. The vegetation plots with significantly lower FD of blossom types than expected by chance were found at higher altitudes, and the proportions of blossom types were strongly patterned along the same gradient. These results support a biotic filtering effect on plant species assemblages through pollination: disk blossoms became dominant at higher altitudes, resulting in a lower FD. In harsh conditions at high altitudes, pollinators usually decrease in activity, and the openness of the disk blossom grants access to any available pollinator. Inversely, bilabiate blossoms, which are mostly pollinated by bees, were more abundant at lower elevations, which are characterised by greater abundance and diversity of bees. Generalisation through openness of the blossom could be advantageous at high elevations, while specialisation could be a successful alternative strategy at lower elevations. The approach used in this study is purely correlative, and further investigations should be conducted to infer the nature of the causal relationship between plant and pollinator distributions.

A sequential model for older workers’ labor transitions after a health shock

In this work we study older workers (50 64) labor force transitions after a health/disability shock. We find that the probability of keeping working decreases with both age and severity of the shock. Moreover, we find strong interactions between age and severity in the 50 64 age range and none in the 30 49 age range. Regarding demographics we find that being female and married reduce the probability of keeping work. On the contrary, being main breadwinner, education and skill levels increase it. Interestingly, the effect of some demographics changes its sign when we look at transitions from inactivity to work. This is the case of being married or having a working spouse. Undoubtedly, leisure complementarities should play a role in the latter case. Since the data we use contains a very detailed information on disabilities, we are able to evaluate the marginal effect of each type of disability either in the probability of keeping working or in returning back to work. Some of these results may have strong policy implications.

On the distribution of income and worker assignment under intra-firm spillovers, with an application to ideas and networks

We study the earnings structure and the equilibrium assignment of workers when workers exert intra-firm spillovers on each other.We allow for arbitrary spillovers provided output depends on some aggregate index of workers' skill. Despite the possibility of increasing returns to skills, equilibrium typically exists. We show that equilibrium will typically be segregated; that the skill space can be partitioned into a set of segments and any firm hires from only one segment. Next, we apply the model to analyze the effect of information technology on segmentation and the distribution of income. There are two types of human capital, productivity and creativity, i.e. the ability to produce ideas that may be duplicated over a network. Under plausible assumptions, inequality rises and then falls when network size increases, and the poorest workers cannot lose. We also analyze the impact of an improvement in worker quality and of an increased international mobility of ideas.

Comparison of neoadjuvant cisplatin-based chemotherapy versus radiochemotherapy followed by resection for stage III (N2) NSCLC.

OBJECTIVE: Comparison of prospectively treated patients with neoadjuvant cisplatin-based chemotherapy vs radiochemotherapy followed by resection for mediastinoscopically proven stage III N2 non-small cell lung cancer with respect to postoperative morbidity, pathological nodal downstaging, overall and disease-free survival, and site of recurrence. METHODS: Eighty-two patients were enrolled between January 1994 to June 2003, 36 had cisplatin and doxetacel-based chemotherapy (group I) and 46 cisplatin-based radiochemotherapy up to 44 Gy (group II), either as sequential (25 patients) or concomitant (21 patients) treatment. All patients had evaluation of absence of distant metastases by bone scintigraphy, thoracoabdominal CT scan or PET scan, and brain MRI, and all underwent pre-induction mediastinoscopy, resection and mediastinal lymph node dissection by the same surgeon. RESULTS: Group I and II comprised T1/2 tumors in 47 and 28%, T3 tumors in 45 and 41%, and T4 tumors in 8 and 31% of the patients, respectively (P=0.03). There was a similar distribution of the extent of resection (lobectomy, sleeve lobectomy, left and right pneumonectomy) in both groups (P=0.9). Group I and II revealed a postoperative 90-d mortality of 3 and 4% (P=0.6), a R0-resection rate of 92 and 94% (P=0.9), and a pathological mediastinal downstaging in 61 and 78% of the patients (P<0.01), respectively. 5y-overall survival and disease-free survival of all patients were 40 and 36%, respectively, without significant difference between T1-3 and T4 tumors. There was no significant difference in overall survival rate in either induction regimens, however, radiochemotherapy was associated with a longer disease-free survival than chemotherapy (P=0.04). There was no significant difference between concurrent vs sequential radiochemotherapy with respect to postoperative morbidity, resectability, pathological nodal downstaging, survival and disease-free survival. CONCLUSIONS: Neoadjuvant cisplatin-based radiochemotherapy was associated with a similar postoperative mortality, an increased pathological nodal downstaging and a better disease-free survival as compared to cisplatin doxetacel-based chemotherapy in patients with stage III (N2) NSCLC although a higher number of T4 tumors were admitted to radiochemotherapy.

New data on the distribution and conservation status of some angiosperms of the Cape Verde Islands, W Africa

New data on the distributibn and conservation status of some angiosperms of the Cape Verde Islands, W Africa Intensive field work aud analysis of the state of biodiversity ou all islands during the years iYY.3 lo IYYY Icd lo lhc publication ol’several contributions lo the flora and vegelalion of the archipclago of Cabo Verde (Brochniann & al. 1997, Gornes & Vera-Cruz 1993. Gonles & al. I9YSa-h. 1998, Games 1997. Kilian & Leyens 1994, Leyens 1998. Leyens & Lobin 1995, Lobin & al. 1995) as well as to the compilation of the First Red Data List for the Cape Verde Islnuds (Lcyrus & Lobin 1996). the elaboration of the National Strategy for Biodiversity Conservation (SIPA 19YY) and ! compilation of all areas in urgent need of protection (Leyens unpubl. diplonla thc.\is IYYJ. Gwnes & al. iu prep.). As part UC the activities of the lnstituto National de Invcstig;u$o c Dcscnvolvitucnto Agriirio (INIDA) and the Dcpurtamcnto de GeociSncias do Institute Supcriot de Educ;u$o t ISE) iutcnsive t’icld studies were conducted PI many diffcrctu localilics OII xcvcr;~I islands. resulting in a thesis tGo~nes IY97) and several terminal study papers (Luz IYYY. Cosi;t 1994. Gonsalvez 1999). The results show that the vegetation and flora of the islands arc still IWI fully known and much more field work is needed. hllhot~gh Sanliiqw is one of lhc islands whcrc lhc firs1 holanicill iIlVcxligilliollx wcrr c:crriul WI (Wcbh 1x49. Schruidt 1x52. Chcvalicr IY35) and where uu~ny intensive field studirs wcrc

The distribution of talent across contests

Do the contests with the largest prizes attract the most able contestants? Towhat extent do contestants avoid competition? In this paper, we show, theoreticallyand empirically, that the distribution of abilities plays a crucial role in determiningcontest choice. Sorting exists only when the proportion of high-ability contestantsis sufficiently small. As this proportion increases, contestants shy away from competitionand sorting decreases, such that, reverse sorting becomes a possibility. Wetest our theoretical predictions using a large panel data set containing contest choiceover three decades. We use exogenous variation in the participation of highly-ablecompetitors to provide empirical evidence for the relationship among prizes, competition,and sorting.

New species of Bakeriella (Hymenoptera, Bethylidae) from the New World and new data on geographic distribution

Bakeriella lata sp. nov. (Brazil, Rondônia), Bakeriella aurata sp. nov. (Brazil, Amazonas) and Bakeriella sulcaticeps sp. nov. (Brazil, Amazonas) are described and illustrated. New geographic records and variation data for B. cristata Evans, 1964, B. floridana Evans, 1964, B. flavicornis Kieffer, 1910, B. incompleta Azevedo, 1994, B. mira Evans, 1997, B. montivaga (Kieffer, 1910), B. olmeca Evans, 1964 and B. subcarinata Evans, 1965 are provided. The male of B. incompleta is described for the first time.

Etude de la distribution de Formica exsecta Nyl. à l 'aide d 'un système d 'information géographique

La distribution de Formica exsecta semble être conditionnée par un bon ensoleillement (pour le développement du couvain) et par le type de végétation (ressources alimentaires). Par la combinaison de ces facteurs à l'aide du SIG, Ramona Maggini a planifié l'échantillonage de 240 stations dans le PNS pour l'analyse de la distribution de cette espèce

Choice by sequential procedures

We propose a rule of decision-making, the sequential procedure guided byroutes, and show that three influential boundedly rational choice models can be equivalentlyunderstood as special cases of this rule. In addition, the sequential procedure guidedby routes is instrumental in showing that the three models are intimately related. We showthat choice with a status-quo bias is a refinement of rationalizability by game trees, which, inturn, is also a refinement of sequential rationalizability. Thus, we provide a sharp taxonomyof these choice models, and show that they all can be understood as choice by sequentialprocedures.

Altruism, uncertain lifetime and the distribution of wealth

This paper studies the dynamics of the distribution of wealth in ageneral equilibrium framework. It considers an overlapping generationsmodel with production and altruistic preferences in which individualsface an uncertain lifetime and annuity markets do not exist. Thispaper focuses on the role that accidental bequests, voluntary bequests,and non--negativity constraints on bequests play in the dynamics of thedistribution of wealth. It is proved that the equilibrium interestrate is lower than the one that satisfies the modified goldenrule. In this economy, a social security system not only plays aninsurance role, but also prevents capital overaccumulation. In fact,this paper shows that a pay--as--you--go social security systemdecentralizes the social planner solution as a competitive equilibrium.

The algebraic equality of two asymptotic tests for the hypothesis that a normal distribution has a specified correlation matrix

It is proved the algebraic equality between Jennrich's (1970) asymptotic$X^2$ test for equality of correlation matrices, and a Wald test statisticderived from Neudecker and Wesselman's (1990) expression of theasymptoticvariance matrix of the sample correlation matrix.

Density and distribution of nests of Mycetophylax simplex (Emery) (Hymenoptera, Formicidae) in areas with mobile dunes on the northern coast of Rio Grande do Sul, Brazil

Studies on lower attines are scarce, especially on nesting and foraging ecology and behavior. This study aimed to contribute to the knowledge of an Attini in dunes ecosystems through the description of density and spatial distribution of Mycetophylax simplex (Emery, 1887) nests in a strip of mobile dunes in the Praia Grande beach, Torres, northern coast of Rio Grande do Sul, Brazil. The density and spatial distribution of nests were estimated in four plots of 2,500 m² each, in which were found 20, 209, 284 and 324 nests, with average densities of 0.01 nests/m², 0.09, 0.11 and 0.13 nests/m², respectively. The nests were found near to the vegetation and showed clumped distribution. The density and distribution pattern of the nests seem to be related to the availability of nesting places and foraging resources.

Seeking theta's desperately: Estimating the distribution of consumers under increasing block rates

This paper shows that the distribution of observed consumption is not a good proxy for the distribution of heterogeneous consumers when the current tariff is an increasing block tariff. We use a two step method to recover the "true" distribution of consumers. First, we estimate the demand function induced by the current tariff. Second, using the demand system, we specify the distribution of consumers as a function of observed consumption to recover the true distribution. Finally, we design a new two-part tariff which allows us to evaluate the equity of the existence of an increasing block tariff.