statacons: An SCons-Based Build Tool for Stata

This paper presents statacons, an SCons-based build tool for Stata. Because of the integration of Stata and Python in recent versions of Stata, we are able to adapt SCons for Stata workflows without the use of an external shell or extensive configuration. We discuss the usefulness of build tools generally, provide examples of the use of statacons in Stata workflows, present key elements of the syntax of statacons, and discuss extensions, alternatives, and limitations. Appendices provide installation instructions and recommendations for collaborative workflows.

Cerium-, Europium- and Erbium-Modified ZnO and ZrO2 for Photocatalytic Water Treatment Applications: A Review

In the last decades photocatalysis has become one of the most employed technologies for the implementation of the so-called Advanced Oxidation Processes (AOPs) for the removal of harmful pollutants from wastewaters. The materials identified as the best photocatalysts are transition metal oxides, in which the band structure allows charge carrier separation upon solar irradiation. The photoinduced charge carrier can thus cause oxidative and reductive redox reactions at the surface, inducing the formation of the radical species able to initiate the AOPs. Despite the great advantages of this process (non-toxic, cheap and environmentally clean), the main drawback lies in the fact that the most efficient semiconductors are only able to absorb UV irradiation, which accounts for only 5% of the total solar irradiation at the Earth’s surface and not enough to generate the required amount of electron-hole pairs. On the other hand, many efforts have been devoted to the sensitization of wide band gap transition metal oxides to visible light, which represents a higher percentage (almost 45%) in the solar electromagnetic spectrum. Among all the strategies to sensitize transition metal oxides to visible irradiation, doping with lanthanides has been less explored. In this regard, lanthanides offer a unique electronic configuration, consisting in 4f orbitals shielded by a 5s5p external shell. This occurrence, coupled with the different occupation of the localized 4f orbitals would provide an astounding opportunity to tune these materials’ properties. In this review we will focus in depth on the modification of two promising photocatalytic transition metal oxides, namely ZnO and ZrO2, with cerium, europium and erbium atoms. The aim of the work is to provide a comprehensive overview of the influence of lanthanides on the structural, optical and electronic properties of the modified materials, emphasizing the effect of the different 4f orbital occupation in the three considered doping atoms. Moreover, a large portion of the discussion will be devoted to the structural-properties relationships evidencing the improved light absorption working mechanism of each system and the resulting enhanced photocatalytic performance in the abatement of contaminants in aqueous environments.

Journeys Through Shape and Time: Palaeobiology of Cenozoic New Zealand Spissatella and Eucrassatella (Bivalvia, Crassatellidae)

<p>A novel, highly-integrated approach combining morphometric, stratocladistic and sclerochronological methods has been applied to two genera of New Zealand Cenozoic crassatellid bivalve (Family Crassatellidae): Spissatella Finlay, 1926 and Eucrassatella Iredale, 1924. This study builds on previous work on Spissatella that demonstrated their amenability to shape analysis and provided a foundation for evolutionary studies of the group. The taxonomy of these crassatellids has been in need of revision; a number of changes to generic placement having been proposed in recent publications without redescription. These bivalves are character-depauperate and known only from fossil material within New Zealand, making them challenging subjects for the phylogenetic analysis that would, ideally, inform taxonomic revision. Geometric morphometric methods have been used to characterise the morphological variation of the study group in terms of shape. Landmarks/semilandmarks that capture internal hard-part morphology and external shell shape, have been compared with internal landmarks only, outline shape semilandmarks only, and outline shape Fourier transform methods, and are shown to best combine comprehensive coverage of total shell form with high correct reassignment of individuals to taxa in multidimensional morphospace. Procrustes-superimposed landmark/semilandmark configurations have been ordinated using Principal Components Analysis (PCA), and PCA plots have been used to compare the shape variation of each species. The independance in morphospace of Spissatella n. sp. C from S. trailli and S. clifdenensis has been established. Covariation of internal morphology and shell-shape has been interpreted as supporting the interdependance of shell and body/mantle proposed by Stasek (1963). PCA scores have been combined with traditional morphological characters and stratigraphic data to produce a phylogenetic tree using stratocladistics, a form of parsimony-based analysis which seeks to minimise combined morphological and stratigraphic debt. This technique also assesses the placement of taxa in ancestral positions on internal nodes of the tree. Combining discretised morphometric data with stratigraphic and morphological data in a single analysis has been shown to produce a more resolved tree than analyses based only on continuous morphometric data. The new analyses demonstrate paraphyly of both Eucrassatella and Spissatella as previously recognised. A taxonomic revision of the studied taxa has been undertaken, incorporating information from both morphometric and phylogenetic studies. Spissatella subobesa and S. maudensis are referred to Eucrassatella. Spissatella discrepans is synonymised with S. acculta. Triplicitella n. gen. and S.maxwelli n. sp. are described. Oxygen isotope analysis has been employed to show that shell-banding in these species is, on average, likely to have been laid down annually. Using this information, the longitudinal dataset of outlines from Crampton & Maxwell (2000) has been recalibrated to use chronological age rather than size to compare shape across taxa, and investigate heterochrony in twelve pairs of species representing either ancestor-descendant, sister-group or lineage-segment relationships. All of the heterochronic processes sensu Gould (1977), namely progenesis, neoteny, acceleration and hypermorphosis, as well as proportioned dwarfism and proportioned gigantism, are identified as having affected evolution within this clade.</p>

Journeys Through Shape and Time: Palaeobiology of Cenozoic New Zealand Spissatella and Eucrassatella (Bivalvia, Crassatellidae)

<p>A novel, highly-integrated approach combining morphometric, stratocladistic and sclerochronological methods has been applied to two genera of New Zealand Cenozoic crassatellid bivalve (Family Crassatellidae): Spissatella Finlay, 1926 and Eucrassatella Iredale, 1924. This study builds on previous work on Spissatella that demonstrated their amenability to shape analysis and provided a foundation for evolutionary studies of the group. The taxonomy of these crassatellids has been in need of revision; a number of changes to generic placement having been proposed in recent publications without redescription. These bivalves are character-depauperate and known only from fossil material within New Zealand, making them challenging subjects for the phylogenetic analysis that would, ideally, inform taxonomic revision. Geometric morphometric methods have been used to characterise the morphological variation of the study group in terms of shape. Landmarks/semilandmarks that capture internal hard-part morphology and external shell shape, have been compared with internal landmarks only, outline shape semilandmarks only, and outline shape Fourier transform methods, and are shown to best combine comprehensive coverage of total shell form with high correct reassignment of individuals to taxa in multidimensional morphospace. Procrustes-superimposed landmark/semilandmark configurations have been ordinated using Principal Components Analysis (PCA), and PCA plots have been used to compare the shape variation of each species. The independance in morphospace of Spissatella n. sp. C from S. trailli and S. clifdenensis has been established. Covariation of internal morphology and shell-shape has been interpreted as supporting the interdependance of shell and body/mantle proposed by Stasek (1963). PCA scores have been combined with traditional morphological characters and stratigraphic data to produce a phylogenetic tree using stratocladistics, a form of parsimony-based analysis which seeks to minimise combined morphological and stratigraphic debt. This technique also assesses the placement of taxa in ancestral positions on internal nodes of the tree. Combining discretised morphometric data with stratigraphic and morphological data in a single analysis has been shown to produce a more resolved tree than analyses based only on continuous morphometric data. The new analyses demonstrate paraphyly of both Eucrassatella and Spissatella as previously recognised. A taxonomic revision of the studied taxa has been undertaken, incorporating information from both morphometric and phylogenetic studies. Spissatella subobesa and S. maudensis are referred to Eucrassatella. Spissatella discrepans is synonymised with S. acculta. Triplicitella n. gen. and S.maxwelli n. sp. are described. Oxygen isotope analysis has been employed to show that shell-banding in these species is, on average, likely to have been laid down annually. Using this information, the longitudinal dataset of outlines from Crampton & Maxwell (2000) has been recalibrated to use chronological age rather than size to compare shape across taxa, and investigate heterochrony in twelve pairs of species representing either ancestor-descendant, sister-group or lineage-segment relationships. All of the heterochronic processes sensu Gould (1977), namely progenesis, neoteny, acceleration and hypermorphosis, as well as proportioned dwarfism and proportioned gigantism, are identified as having affected evolution within this clade.</p>

Another lesson from beautiful monsters: the case of 'sex reversals' in the Ammonoidea and their significance

Background Expression of sexual dimorphism is recognised in various fossil groups of molluscs such as the Ammonoidea, an extinct group of shelled cephalopods. During the Mesozoic, the best-documented sexual dimorphic examples are seen in the Jurassic superfamily Perisphinctoidea. It is usually expressed by distinct adult size and apertural modifications between the antidimorphs. Putative males (otherwise referred to as microconch) are small in size and develop lappets at the end of the shell while the females (macroconch) are larger and bear a simple peristome. Dubious cases are, however, known in that superfamily, which often relate to taxonomic biases or lack of diagnostic characters, and some others expose ontogenetic anomalies illustrated by ‘sex reversals’ in the shell morphology and ornamentation. Results The discovery of two specimens of the Callovian Aspidoceratidae Peltoceras athleta (Phillips), having both female and male features, questions the significance and causes of ‘sex reversals’ in the Ammonoidea. The two specimens have started with the macroconch ontogeny of Peltoceras athleta and show an apparent change toward maleness in the adult, as illustrated by their rounded whorl section, ribs retroversion, fading of the tubercles and lappets typical of the microconchs. Few other cases of female-to-male, as well as male-to-female ‘sex reversal’, are known in the fossil record, all belonging to the Jurassic Perisphinctoidea (families Perisphinctidae or Aspidoceratidae). Since all Jurassic Perisphinctoidea are strictly gonochoristic, these ‘sex reversals’ are pathological in nature and are herein referred to as a new forma-type pathology: namely “forma hermaphrodita”. Conclusions In the absence of any clear evidence of injury or parasitism, we hypothesize that such “forma hermaphrodita” individuals illustrate pathologic cases of intersexuality. Little is known about the ammonoid soft parts, and it is not possible to determine which internal sexual organs occur in specimens having both male and female external shell features. Abnormal feminisation and/or masculinisation also occur in modern cephalopods, the latter also grouping only gonochoric species. This phenomenon is similarly illustrated by a change in the adult body size and a mixing of both female and male structures. In that case, intersexuality is either advantageous in the population or caused sterility. The causes of intersexuality are not clearly established but environmental pollutants are evoked in modern cephalopods because they act as endocrine disrupters. ‘Sex reversals’ and/or non-functional reproductive abnormalities have also been caused by endocrine disrupters in various gonochoric gastropods species, but infestation, genetic abnormalities, temperature fluctuations or viruses are multiple causes, which can stimulate or inhibit neural-endocrinal activity by direct gonadal influence, and ultimately lead to feminisation or masculinisation in fishes, isopods, crustaceans, and gastropods as well. Regardless of whether “forma hermaphrodita” is due to an exogenic or endogenic cause, the record of intersex Perisphinctoidea in the Jurassic can be explained by the ready recognition of dimorphic pairs, and the easy collection of large and sufficiently preserved fossil palaeopopulations in which intersex specimens have statistically more chance to be found.

A Literature Review of Biological and Bio-Rational Control Strategies for Slugs: Current Research and Future Prospects

Terrestrial gastropod molluscs (slugs and snails) (Mollusca: Gastropoda) cause significant crop damage around the world. There is no formal approach for differentiating between slugs and snails; however, an organism is usually considered a slug when there is no external shell, or when the shell is small in comparison to the body, and a snail when there is a large external shell. Although snails are an important pest of many crops, this review focuses on slug pests and their nonchemical control measures. A recent study by the UK Agriculture and Horticulture Development Board concluded that the failure to control slugs could cost the UK agriculture industry over GBP 100 million annually, with similar figures reported around the world. Whilst slugs are mostly controlled using chemical molluscicide products, some actives have come under scrutiny due to their detrimental environmental effects and impact on nontarget organisms. This has resulted in the ban of actives such as methiocarb in the UK and EU, and, more recently, the ban of metaldehyde in the UK. Therefore, there is an urgent need to find alternative and effective nontoxic solutions in the interest of global food security. In this paper, we have integrated extant literature on the three main biological control agents of slugs, namely nematodes, carabid beetles and sciomyzid flies, and various promising bio-rational slug control strategies. The review also highlights current research gaps and indicates some relevant potential future directions towards developing environmentally benign slug control solutions.

Strength of Concrete-Filled Plastic Tube Stub Columns Using a Normalized Stiffness Approach

The polymeric plastic tube can encase concrete and provide an external shell for confining and insulating concrete core from the impact of the surrounding environment. The effect of the tube and concrete strength on the concrete-filled plastic tubes (CFPT) stub columns specimens was investigated. Test results show that the tube provides passive confinement to the concrete core, which increases both the maximum peak load and the ultimate strain capacities. However, the tube has low stiffness, which affects its confinement capacity and hindrance its applications for structural use. To examine the role of tube stiffness and express the strength of a concrete-filled plastic tube, a previously proposed normalized stiffness approach for both active and passive confinement of FRP-confined concrete was adopted for the present study. From the perspective of stiffness and to better understand the behavior of CFPT specimens under uniaxial compression loads, a database of recent studies were assembled combined with the results of the present study. Several existing strength models for FRP-confined concrete were also used to predict the mechanical strength of CFPT. Two models were proposed with good predictions of the experimental results of the database.

Nitrogen isotope sclerochronology - insights into coastal environmental conditions and Pinna nobilis ecology

&lt;p&gt;&lt;em&gt;Pinna nobilis&lt;/em&gt; is a large bivalve endemic to the Mediterranean Sea that lives in shallow coastal areas. Due to its size and relatively fast shell growth rates, it is an interesting taxon for high resolution geochemical and sclerochronological research. Subsequently to previous analyses of &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C in &lt;em&gt;P. nobilis&lt;/em&gt; shells, here, we investigate nitrogen isotopes in the carbonate-bound organic matrix (&amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt;) of this species. Our objectives were to test if &lt;em&gt;P. nobilis&lt;/em&gt; shells (i) can be used as an indicator of the isotopic baseline of the system, and (ii) is a good candidate for obtaining high-resolution temporal data on environmental &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N variability. Due to the multiple mass mortality events of &lt;em&gt;P. nobilis&lt;/em&gt; spreading throughout the Mediterranean, including the Adriatic Sea, we also tested if (iii) &lt;em&gt;P. nobilis&lt;/em&gt; geochemistry changes as a response to diseases.&lt;/p&gt;&lt;p&gt;Shells were opportunistically collected by skin diving from 4 shallow coastal localities in the eastern Adriatic, as a part of a project on mortality monitoring. Specimens from Lim channel (October 2019), Ka&amp;#353;tela Bay (January 2020) and Mali Ston Bay (November 2019) were collected alive, while in Pag Bay, shells of three recently dead specimens were collected in September 2020. Tissue and epibionts were removed and shells carefully cleaned and air-dried. Shell powder was collected by milling sample swaths by hand using a DREMEL Fortiflex drill equipped with a 300 &amp;#956;m tungsten carbide drill bit. For &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; analysis, three shells from each locality were processed and three replicas were collected from each of these shells by milling shallow lines parallel to the growth axis from the internal shell surface. In addition, high-resolution &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; data were obtained for one shell from Ka&amp;#353;tela by milling lines (N=40) perpendicular to the major growth axis from the external shell surface. From this shell we also collected shell powder for &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;shell&lt;/sub&gt; and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;shell&lt;/sub&gt; analysis to enable placing &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; into temporal context. Isotope samples were analyzed Union College on an elemental analyzer - isotope ratio mass spectrometer.&lt;/p&gt;&lt;p&gt;Results indicate significant differences in &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; between sampling localities, with lowest values recorded for shells from Pag Bay (3.73&amp;#177;0.36&amp;#8240;), and highest for shells sampled in Lim channel (7.04&amp;#177;0.63&amp;#8240;). High-resolution &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; data obtained from the shell collected from Ka&amp;#353;tela Bay corresponded to a time interval from spring 2018 to spring 2019. These data showed relatively small variations (5.02&amp;#177;0.33&amp;#8240;). However, &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; values increased to 8.65&amp;#177;1.61&amp;#8240; closest to the shell margin, and were coupled with a decrease in &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;shell&lt;/sub&gt; values, indicating that this animal was experiencing stressful conditions several months prior to its death. According to our findings, &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N&lt;sub&gt;CBOM&lt;/sub&gt; values serve as an indicator of the isotopic baseline of the ecosystem as well as a potential powerful tool to study bivalve physiology.&lt;/p&gt;&lt;p&gt;Research was the supported by the Croatian Science Foundation, research project BivACME.&lt;/p&gt;

Synthesis and Properties of Hybrid Carbosilane Dendrimers with Cyclosiloxane External Shells

The hydrosilylation of polyallylcarbosilane dendrimers with hydride-containing six- and eight-membered dimethylcyclosiloxanes affords a series of hybrid carbosilane–siloxane dendrimers featuring different densities of the surface cyclosiloxane layers, while retaining all other molecular parameters. The main physicochemical constants of the resulting dendrimers are defined. The possibility of functionalization of these dendrimers by the opening of cyclosiloxane structural moieties in the external shell is demonstrated by the example of the zero-generation dendrimer bearing heptamethylcyclotetrasiloxane terminal groups.

Another Lesson From Beautiful Monsters: the Case of 'sex Reversals' in the Ammonoidea and Their Significance

Background: Expression of a sexual dimorphism is recognised in various fossil groups of molluscs such as the Ammonoidea, an extinct group of shelled cephalopods. During the Mesozoic, the best documented sexual dimorphic examples are seen in the Jurassic superfamily Perisphinctoidea. It is most usually expressed by distinct adult size and apertural modifications between the antidimorphs. Putative males (otherwise referred to as microconch) are small in size and develop lappets at the end of the shell while the females (macroconch) are larger and bear a simple peristome. Dubious cases are, however, known in that superfamily. They most often relate to taxonomic biases or lack of diagnostic characters, and some others expose ontogenetic anomalies illustrated by ‘sex reversals’ in the shell morphology and ornamentation. Results: The discovery of two specimens of the Callovian Aspidoceratidae Peltoceras athleta (Phillips), having both female and male features, questions the significance and causes of ‘sex reversals’ in the Ammonoidea. The two specimens have started with the macroconch ontogeny of Peltoceras athleta, and show an apparent change toward maleness in the adult, as illustrated by their rounded whorl section, ribs retroversion, fading of the tubercles and lappets typical of the microconchs. Few other cases of female-to-male ‘sex reversal’, as well as male-to-female ones, are known in the fossil record, all belonging to the Jurassic Perisphinctoidea (families Perisphinctidae or Aspidoceratidae). Since all Jurassic Perisphinctoidea are strictly gonochoristic, these ‘sex reversals’ are pathological in nature and are herein referred to as a new forma-type pathology: namely “forma hermaphrodita”.Conclusions: In the absence of any clear evidence of injury or parasitism, we hypothesize that such “forma hermaphrodita” individuals illustrate pathologic cases of intersexuality. Little is known about the ammonoid soft parts, and it is not possible to determine which internal sexual organs occur in specimen having both male and female external shell features. Abnormal feminisation and/or masculinisation also occur in modern cephalopods; the latter also grouping only gonochoric species. This phenomenon is similarly illustrated by a change in the adult body size and a mixing of both female and male structures. In that case, intersexuality is either advantageous in the population or caused sterility. The causes of intersexuality are not clearly established but environmental pollutants are evoked in modern cephalopods because they act as endocrine disrupters. ‘Sex reversals’ and/or non-functional reproductive abnormalities have also been caused by endocrine disrupters in various gonochoric gastropods species, but infestation, genetic abnormalities, temperature fluctuations or viruses are multiple causes which can stimulate or inhibit neural-endocrinal activity by direct gonadal influence, and ultimately lead to feminisation or masculinisation in fishes, isopods, crustaceans, and gastropods as well. Regardless of whether “forma hermaphrodita” is due to an exogenic or endogenic cause, the high frequency of intersex Perisphinctoidea in the Jurassic can be explained by the readily recognition of dimorphic pair, and the easy collection of large and sufficiently preserved fossil palaeopopulations in which intersex specimens have statistically more chance to be found.