7,261 research outputs found
Bringing Hidden Organizations Out of the Shadows: Introduction to the Special Issue
No full textThis introduction to the special issue describes hidden organizations, offers several reasons for the lack of research on these collectives, and explains how this collection of articles helps move us forward in efforts to empirically study hidden organizations. After providing background information on the history of this special issue, the five articles published here are described in terms of the type of collective examined, the theories and methods used, and the key research questions addressed. Three observations about the published pieces are made: being hidden requires communicative effort; hiddenness is usefully understood in terms of identity management; and any discussion of hidden organizations raises ethical considerations. The piece closes with acknowledgements and a call for continued conceptual/theoretical and empirical research into hidden organizations.This is an introduction to a special issue on Hidden Organizations edited by the author. Published online before print: July 19, 2015
Thrombo-embolism of the subclavian artery : a case report
No full textCITATION: Knott-Craig, C. J. & Buhrman, J. R. 1985. Thrombo-embolism of the subclavian artery : a case report. South African Medical Journal, 67:428-429.The original publication is available at http://www.samj.org.zaAcute thrombo-embolic occlusions of the subclavian artery account for less than 1% of all acute arterial occlusions of the extremities. One such case is presented and the management discussed with special reference to the technique of embolectomy and the treatment of the reperfusion syndrome with either fasciotomy or mannitol. The question of anticoagulation is also examined.Publisher’s versio
Craig interpolation for semilinear substructural logics
No full textThe Craig interpolation property is investigated for substructural logics whose algebraic semantics are varieties of semilinear (subdirect products of linearly ordered) pointed commutative residuated lattices. It is shown that Craig interpolation fails for certain classes of these logics with weakening if the corresponding algebras are not idempotent. A complete characterization is then given of axiomatic extensions of the >R-mingle with unit> logic (corresponding to varieties of Sugihara monoids) that have the Craig interpolation property. This latter characterization is obtained using a model-theoretic quantifier elimination strategy to determine the varieties of Sugihara monoids admitting the amalgamation property. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.The first author was supported by the Spanish projects TASSAT (TIN2010-20967-C04-01) and Agree-
ment Technologies (CONSOLIDER CSD2007-0022, INGENIO 2010), the Generalitat de Catalunya grant 2009-SGR-1434, and the Marie Curie IRSES Project (FP7-PEOPLE-2009). The second author was supported by Swiss National Science Foundation grant 20002 129507 and Marie Curie Reintegration Grant PIRG06-GA-2009-256492.Peer Reviewe
On the timing of innovation in stochastic Schumpeterian growth models
No full textRecent work has revived the Schumpeterian hypothesis that recessions facilitate innovation and growth. But a major source of productivity growth, research and development, is actually procyclical. This paper argues that while it is optimal to concentrate growth enhancing activities in downturns, dynamic spillovers inherent to the R&D process lead private agents to concentrate too much of their R&D activity in booms, precisely when its social cost is highest. Thus, while previous literature has argued recessions promote growth and intertemporal substitution is a desirable consequence of fluctuations, in the case of R&D recessions discourage growth and intertemporal substitution proves to be a social liability.Research and development
EVALUATING AGRICULTURAL RESEARCH AND PRODUCTIVITY IN AN ERA OF RESOURCE SCARCITY
No full textProceedings of a Symposium Sponsored by NC-208, "Impact Analysis and Decision Strategies for Agricultural Research" held at Orlando, Florida, March 4, 1993. Contents: The Federal Context for Funding Agricultural Research, by Daryl Chubin Agricultural Research Structures in a Changing World, by Brian Wright and David Zilberman Priority Setting in a State Agricultural Experiment Station: Shifting Paradigms, by Bill R. Baumgardt Structure, Management and Funding of Agricultural Research in the United States: Current Directions and Likely Impact, by Wallace Huffman and Richard Just Impact of Changing Intellectual Property Rights on U.S. Plant Breeding R&D, by Carl E. Pray, Mary Knudson and Leonard Masse A New Look at State-Level Productivity Growth in U.S. Agriculture, by Philip G. Pardey, Barbara J. Craig and Klaus Deininger Measuring Agricultural Productivity in U.S. Agriculture, by V. Eldon BallProductivity Analysis, Research and Development/Tech Change/Emerging Technologies,
Maxillary Sinusitis Following Orthognathic Surgery: Should It Be Considered Odontogenic Sinusitis?
No full textMaxillary sinusitis is a recognized complication following dental procedures, but its occurrence after orthognathic surgery, such as Le Fort osteotomies, remains less documented. This case report presents a 58-year-old female who developed unilateral maxillary sinusitis 23 years post-orthognathic surgery. The patient was asymptomatic, aside from occasional cacosmia, and was incidentally found to have sinus opacification on a computed tomography (CT) scan performed for implant-prosthetic rehabilitation. Nasal endoscopy revealed purulence and mucosal edema, prompting endoscopic sinus surgery (ESS). Intraoperatively, purulent material and fungal debris were removed from the maxillary sinus, confirming bacterial sinusitis with a concurrent fungal ball. S. salivarius and Klebsiella species were identified from the cultures. The patient's condition improved following the removal of both the sinus contents and the retained titanium plates and screws. This case underscores the potential for maxillary sinusitis to develop long after orthognathic surgery, particularly in the presence of retained dental hardware. It highlights the importance of thorough imaging and endoscopic evaluation in patients with a history of dental or facial surgeries presenting with sinonasal symptoms. Additionally, it raises questions about the role of retained hardware in the persistence or recurrence of infection and the possible association with fungal ball formation. The need for further research to establish guidelines for the management of sinusitis in such contexts, particularly regarding the removal of facial hardware, is emphasized
Protaustrosimulium Currie & Craig & Moulton 2018, n. gen.
No full textProtaustrosimulium n. gen. Currie, Craig & Moulton Type species: Cnephia pilfreyi Davies & Györkös 1988: 107. Members of the Protaustrosimulium terebrans -group, as defined below (i.e., Prot. terebrans and Prot. opscurum n. sp.) are known only as adult females. Accordingly, the following diagnosis is confirmed just for that particular life stage. Character states of males, pupae and larvae apply definitely only to members of the Prot. pilfreyi -group; however, a subset of these states may eventually prove to be diagnostic of the genus as a whole. Diagnosis. Female: small, darkly coloured flies. Head: antenna with nine flagellomeres. Lateral cervical sclerites well expressed. Thorax: not markedly domed; katepisternal sulcus well defined and more or less complete anteriorly; katepisternum and anepisternal membrane bare. Wing: rather fumose, especially apically, with darkly pigmented veins; basal medial (bm) cell present, but minute (absent in male of Prot. pilfreyi); membrane surrounding r-m junction not markedly pigmented; a:b ratio ca. 1.0:2.8; Costa with short spinules interspersed among typical setae on apical half; vein Rs unbranched; R 1 and R s closely approximated distally, confluent before junction with C; basal section of R haired; M 1 appears doubled distally; CuA slightly sinuous. Legs: basitarsus without row of stout spines ventrally; calcipala well developed, with base one-third to one-half width of hind basitarsus apex; pedisulcus present but variously expressed; tarsal claws smoothly and shallowly curved, with small basal tooth arising from medial side of claw, heel small to well expressed. Genitalia: spermatheca with pigmentation extended markedly onto apex of spermathecal duct (condition unknown in Prot. opscurum). Male: details of head, thorax and wing as described for females. Genitalia: gonostylus slightly shorter than gonocoxite, with three to five short apical spines; ventral plate trapezoidal shaped, with distinct median keel; paramere platelike, subtriangular, with four long apical spines; aedeagal membrane with microtrichia; median sclerite deeply forked. Pupa: gill thin-walled and transparent, consisting of 6–10 short finger-like filaments; thoracic notum smooth, with typical array of setae; abdominal cuticle thin and lightly pigmented; pleurites absent; abdominal armature sparse, with hooks present only on tergites V and VI; spine combs minute, present on tergites VI–IX; anchor-shaped hooks present on pleura of terminal abdominal segments; terminal spines minute. Cocoon: shoeshaped or slipper-shaped, without anterior rim, constructed of fine loosely woven silk covering most of pupa. Larva: antenna extended well beyond apex of labral fan base; article length ratio (basal:medial:distal) ca. 3:1:7; basal and medial articles relatively thick and brown, distal article relatively thin (ca. one-third width of other articles) and hyaline; cervical sclerites not fused to postocciput; hypostoma with apical teeth not arranged on prominent lobes; teeth partially covered by ventral wall of hypostoma; tooth 0 and 4 most prominent; lateral serrations absent; postgenal cleft virtually absent, represented at most by narrow inverted-V shaped notch; abdomen with ventral tubercles well expressed; anal sclerite X-shaped, interarm struts absent; accessory and semicircular sclerites present; rectal papillae of three simple lobes. Distribution. Australia; with species distributed vicariously in New South Wales, the Australian Capital Region and Victoria in the southeast, and Western Australia in the west. Etymology. In reference to the apparent close relationship between the species under consideration to Austrosimulium, Paraustrosimulium and Cnesiamima Wygodzinsky & Coscarón 1973. Constituents. Protaustrosimulium pilfreyi (Davies & Györkös) n. comb. Prot. amphorum n. sp., Prot. terebrans (Tonnoir) n. comb, and Prot. opscurum n. sp. Discussion. Protaustrosimulium n. gen. is here established for four species of Australian black flies that share a close relationship with Austrosimulium, Paraustrosimulium, and Cnesiamima. They share with Austrosimulium a markedly similar wing venation, wherein R 1 and R s are closely approximated distally, becoming confluent before joining the costa. (e.g., Figs. 29, 30). This state is clearly synapomorphic for members of these two genera, as R 1 and R s join the costa separately in Paraustrosimulium, Cnesiamima and all other simuliids. The wings of all four genera have a similar a:b ratio (i.e., they all have a relatively short basal radial (br) cell that extends ca. one fourth length of wing as measured from cell base) and possess a small but distinct basal medial (bm) cell. Although the immature stages are unknown for members of the terebrans -group, larvae and pupae of the pilfreyi -group share a number of synapomorphic character-states with Austrosimulium, Paraustrosimulium and Cnesiamima. One such state is the elongate distal antennal article of larvae, which is two times or more the length of the basal and medial article combined. The hypostoma of the four genera are also similar in that their apical teeth are not grouped on prominent lobes and further are partially covered by the ventral wall of the hypostoma (e.g., Fig. 16). Another character-state shared between Protaustrosimulium and Austrosimulium s. str. (but not by Austrosimulium (Novaustrosimulium), Paraustrosimulium and Cnesiamima) is presence of accessory and semicircular sclerites on the posterior proleg of larvae. Although similar structures occur elsewhere in the Simuliidae, such as in Parasimulium crosskeyi Peterson, Gigantodax Enderlein, Simulium (Gomphostilbia) palauense Stone (Takaoka & Craig, 1999) and Crozetia Davies (Craig et al., 2003) they are likely to be independently evolved based on marked differences in their expression. As shown by Craig et al. (2012: 285), a clear ring of cuticle surrounds and supports the circlet of hooks, and while parts of the ring may be darkly pigmented, as is the case in most Austrosimulium species and members of the Prot. pilfreyi- group (Figs. 21, 66), the structure is actually present in all simuliid larvae examined. The semicircular sclerite then, when expressed, is merely pigmentation of the ring. Accordingly, while this underlying cuticle is homologous across the Simuliidae, its expression, when sclerotized and pigmented, is subject to homoplasy. Nonetheless, the form of the accessory and semicircular sclerites is markedly similar in members of the pilfreyi -group and Austrosimulium s. str., perhaps suggesting a common origin. Pupae of Protaustrosimulium, Austrosimulium, Cnesiamima and Paraustrosimulium are similar in that their abdominal armature is weakly expressed, the terminal spines are minute (Fig. 55), and the pleura of the terminal segments are endowed with anchor- or grapnel-shaped hooks. Finally, the hind basitarsus of female Protaustrosimulium, plus those of A. australense and members of the A. ungulatum species-group, lack a row of stout setae that runs parallel to the comb in other simuliids (Craig et al., 2012: 54). This character state either provides further evidence of a close relationship between Protaustrosimulium and Austrosimulium, or perhaps represents a synapomorphy (albeit a homoplasious one) of the new genus. Although Protaustrosimulium shares many of the above-mentioned features with Austrosimulium and Paraustrosimulium, it lacks synapomorphies that link those latter two genera together. For example, Protaustrosimulium has nine (as opposed to eight) antennal flagellomeres, and lacks (as does Cnesiamima) interarm struts on the anal sclerite. Protaustrosimulium can be further distinguished from Austrosimulium in lacking the following autapomorphies of that genus; namely, Protaustrosimulium females have serrations on both sides of the mandible (as opposed to just on the inner side), and their pupae have spine combs on abdominal tergites VI–VIII (as opposed to lacking spine combs altogether). In summary, the character state distribution in Protaustrosimulium is muddled, with different sets of relationships suggested depending on how characters are interpreted. Arbitrary assignment of the species in question to either Austrosimulium or Paraustrosimulium would render diagnosis of those genera difficult. We therefore prefer to recognize a new genus in order to maintain current generic concepts as far as possible. An alternative approach would be to recognize just a single Austral genus— Austrosimulium s. lat. —with five subgenera, viz., Austrosimulium s. str., Novaustrosimulium, Paraustrosimulium, Cnesiamima and Protaustrosimulium. However, as noted above, marked structural disparity among included taxa would make generic diagnosis difficult. While it is clear that Protaustrosimulium shares an immediate common ancestry with Austrosimulium, Paraustrosimulium, and Cnesiamima, monophyly of the new genus is less certain—mainly because adult females are the only life stage known for all four species. One possible synapomorphy is a spermatheca with pigmentation extended markedly into the apex of the spermathecal duct. Unfortunately, however, the spermatheca of Prot. opscurum is unknown, and this particular state is variously expressed in other simuliids, including Cnesiamima and Paraustrosimulium. Males and immature stages of the terebrans -group are needed to more fully assess monophyly of Protaustrosimulium as here defined. The distribution of Protaustrosimulium (Fig. 99), with sister species split between southern Western Australia and the southeastern States, follows closely that of the other Gondwanan simuliid taxa. This, as discussed by Craig et al. (2017, 2018a, 2018b) and Moulton et al. (2018) likely involved inundation of the Nullarbor Plain area by the Eromanga Sea during the Eocene and Miocene, and subsequent desertification. pilfreyi -group. Genital fork with rod-like anterior arm and membranous lateral region (Figs. 5, 35). Constituents. Protaustrosimulium pilfreyi (Davies & Györkös 1988) and Protaustrosimulium amphorum n. sp.Published as part of Currie, Douglas C., Craig, Douglas A. & Moulton, John K., 2018, A new genus, Protaustrosimulium, for four species of Australian black flies (Diptera: Simuliidae), pp. 301-334 in Zootaxa 4521 (3) on pages 302-304, DOI: 10.11646/zootaxa.4521.3.1, http://zenodo.org/record/260990
The marine ΔR For Nenumbo (Solomon Islands): A case study in calculating reservoir offsets form paired sample data
No full textIt is necessary to calculate location-specific marine ΔR values in order to calibrate marine samples using calibration curves such as those provided through the IntCal98 (Stuiver et al. 1998) data. Where known-age samples are available, this calculation is straightforward (i.e. Stuiver et al. 1986). In the case that a paired marine/terrestrial sample calculation is performed, however, the standard calculation (i.e. Stuiver and Braziunas 1993) requires that the samples are treated as relating to isochronous events. This may not be an appropriate assumption for many archaeological paired samples. In this paper, we present an approach to calculating marine ΔR values that does not require the dated events to be treated as isochronous. When archaeological evidence allows the dated events to be tightly temporally constrained, the approach presented here and that described by Stuiver and Braziunas (1993) give very similar results. However, where tight temporal constraints are less certain, the 2 approaches can give rise to differing results. The example analysis considered here shows that a ΔR of –81 ± 64 ¹⁴C yr is appropriate for samples in the vicinity of Nenumbo (Reef Islands, southeast Solomon Islands) around the period 2000–3000 BP
Dataset supporting the doctoral thesis "Assessing the impacts of future climate change on homegarden agroforestry systems: A case study on Mt Kilimanjaro's SE slopes"
No full textThe dataset is a mainly socio-economic quantitative household survey that measures indicators representing subsistence farmers' crop yield and household wellbeing in a homegarden agroforestry system in Tanzania's Moshi Rural District. The dataset was gathered for the purpose of assessing how a change in climate conditions (warmer and drier) could affect the wellbeing of subsistence farmers in the homegardens following a climate analogue analysis study design. This study pertains to Chapter 6 in the doctoral thesis "Assessing the impacts of future climate change on homegarden agroforestry systems: A case study on Mt Kilimanjaro's SE slopes".
The dataset includes:
-Hard_Copy_HH_Survey.pdf
-Coding_Sheet.xlsx
-Moshi_Homegarden_Data.xlsx
-Conversion_Units.pdf
The data will become available after the embargo of 4.12.2024 and can be accessed with CC BY license. </span
A new DLVO-R Theory: Surface Roughness and Nanoparticle Stability
No full textConventional theory of surface forces and nanoparticle aggregation assumed particles had smooth surfaces. But real particles have a degree of surface roughness, typically characterized by root mean square roughness, σ_m. A theory of surface forces can account for the impact of surface roughness chiefly in two distinct ways. Firstly, shorter distances between asperities, which means that short-range noncontact interactions are amplified, be it attractive or repulsive. Secondly, asperities in contact introduce a repulsive contact force. We present simple analytical formulas for these effects. The contact force is determined by the elastic modulus of materials and the average radius a_r of asperity tips. Contact repulsion exceeds noncontact forces to form a repulsive barrier when surfaces are separated by a distance less than 3–5 σ_m. Consequently, the general effect of surface roughness is to impede aggregation or adhesion of nanoparticles. The theory has been tested with measurements of surface forces of titania and hafnia surfaces using atomic force microscopy. Repulsive forces are found even in the case of minimal surface roughness with σ_m only 0.5–1 nm
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