15,775 research outputs found
Transient electron energy distribution in supported Ag nanoparticles
No full textMerschdorf M, Kennerknecht C, Willig K, Pfeiffer W. Transient electron energy distribution in supported Ag nanoparticles. New Journal of Physics. 2002;4(1):95.The electron relaxation in Ag nanoparticles supported on graphite is investigated by time- resolved multiphoton photoemission spectroscopy. The photoemission spectra map the transient electron energy distribution in the nanoparticles and reveal the internal thermalization and cooling of the electron gas. The excess energy stored in the electron gas is calculated using the free-electron model. In contrast to the behaviour of isolated nanoparticles the energy loss rate from the electron gas increases with the pump fluence. This indicates that the electron gas equilibration in Ag nanoparticles on graphite is modified by excited electron transport
Managing Technology Risks Through Technological Proficiency: Guidance for Local Governments
No full textLike most organizations, local governments face challenges managing technology, the critical resource to meet evolving public service expectations. But benefits associated with adapting the latest technology come with risks, some more apparent than others.
This report details the problems facing municipal officials as they try to maximize the benefits of technology for their communities and constituents in the face of cybersecurity, legal, operational, financial, reputational and societal risks.
The report concludes that top municipal officials must create and maintain an environment of “technological proficiency.” That includes creating a process for making technology decisions, developing an annually reviewed technology plan that is tied to the budget, instituting a “cyber hygiene” training program for all employees in proper computer security practices, and making sure that agency technology is competently managed.
The report is supplemented by a "Best Practices and Resources Guide" that organizations can use to achieve technology proficiency. It provides best practices based on an organization's technology profile.Report and Supplement were prepared for the Municipal Excess Liability Fund, a joint insurance fund of over 600 New Jersey local government agencies
Evaluation of binocular eye trackers and algorithms for 3D gaze interaction in virtual reality environments
No full textPfeiffer T, Latoschik ME, Wachsmuth I. Evaluation of binocular eye trackers and algorithms for 3D gaze interaction in virtual reality environments. JVRB - Journal of Virtual Reality and Broadcasting. 2008;5(16):1660.Tracking user's visual attention is a fundamental aspect in novel human-computer interaction paradigms found in Virtual Reality. For example, multimodal interfaces or dialogue-based communications with virtual and real agents greatly benefit from the analysis of the user's visual attention as a vital source for deictic references or turn-taking signals. Current approaches to determine visual attention rely primarily on monocular eye trackers. Hence they are restricted to the interpretation of two-dimensional fixations relative to a defined area of projection. The study presented in this article compares precision, accuracy and application performance of two binocular eye tracking devices. Two algorithms are compared which derive depth information as required for visual attention-based 3D interfaces. This information is further applied to an improved VR selection task in which a binocular eye tracker and an adaptive neural network algorithm is used during the disambiguation of partly occluded objects
Paul Pfeiffer, Rice University
No full textA portrait of Dr. Paul Pfeiffer, Professor in the Mathematics Department, William M. Rice Institute. He is wearing a dark suit and tie. Original resource is a black and white photograph.Dr. Paul Pfeiffer joined the faculty of the Rice Institute in 1947 and taught for more than 50 years
Halotudora gruneri Pfeiffer 1846
No full textHalotudora gruneri (Pfeiffer, 1846) Figures 3 A–N, 12 B Type material. Cyclostoma gruneri Pfeiffer, 1846: NHMUK unnumbered (3), specimens from Cuming collection bearing Pfeiffer’s handwriting of “Dyson, Honduras ” may be syntypes. Cyclostoma radiosum Morelet, 1849: ANSP 14097 (1), as syntype in Richardson et al., 1991. Type locality. Cyclostoma gruneri Pfeiffer, 1846: “in Honduras.” Restricted by Thompson (2011) to Belize. Cyclostoma radiosum Morelet, 1849: “ petrosa provinciae Petenensis.” Type figured. Cyclostoma gruneri Pfeiffer, 1846: Pfeiffer, 1847 b: pl. 10, figs. 28, 29. Cyclostoma radiosum Morelet, 1849: unfigured. Cresonymy. Cyclostoma gruneri Pfeiffer, 1846: 47; Pfeiffer, 1847 a: 105; Pfeiffer, 1847 b: 79 –80, pl. 10, figs. 28, 29; Pfeiffer, 1848: 79 –80; Petit de la Saussaye, 1850: 45; Watters, 2006: 283. Cyclostoma radiosum Morelet, 1849: 22; Watters, 2006: 430. Cistula ? gruneri (Pfeiffer, 1846). Gray, 1850: 59. Cistula gruneri (Pfeiffer, 1846). Pfeiffer, 1851: 170; Pfeiffer, 1852 a: 264 –265; Pfeiffer, 1853 a: 185; Adams & Adams, 1856: 294; Pfeiffer, 1858: 131; Pfeiffer, 1865: 142; Bland, 1866: 61; Pfeiffer, 1876: 187; Fischer & Crosse, 1890: 218. Chondropoma gruneri (Pfeiffer, 1846). Reeve, 1863 b: pl. 9, fig. 68; Martens, 1890: 14, 18. Ctenopoma grüneri (Pfeiffer, 1846). Fischer & Crosse, 1890: 188, 191. Chondropoma (Chondropoma) grunneri [sic] (Pfeiffer, 1846). Henderson & Bartsch, 1921: 62. Choanopoma (Choanopomops) gruneri (Pfeiffer, 1846). Solem, 1961: 195, 203. Halotudora gruneri (Pfeiffer, 1846). Watters, 2006: 73, 283. Chondropoma (Chondropomium) gruneri (Pfeiffer, 1861). Thompson, 2011: 44, 278. Distribution and habitat. Endemic to limestone outcrops of the Maya Mountains and Vaca Plateau in Cayo and Toledo districts, Belize, and adjacent Livingston area in Izabal Department, Guatemala. Often abundant. Conservation. Portions of the populations occur in the Swasey Bladen and Columbia Forest reserves in Belize. Other material (specimens examined: 324). Belize. Belize District: UF 135010 (32), Rockville quarry, 125 m. Toledo Department: UF 207837 (1), UF 207776 (125), limestone ridge 1.0 km S of Aguacate, 100 m; UF 13532 (18), quarry near San Pedro Columbia; UF 207738 (48), limestone ridge 2.0 km N of Blue Creek, 75 m; UF 207876 (92), limestone hill 3.2 km E of Blue Creek, 75 m; UF 207683 (86), limestone hill 1.0 km W of San Felipe, 75 m; UF 211817 (4), Bladen Columbia Forest Reserve; UF 207915 (12), limestone ridge 4.5 km S of Trio, 100 m; UF 371986 (15), summit at entrance to cave, Cerrito. Cayo District: UF 135109 (5), vicinity of Herman’s Cave and Blue Hole National Park; UF 135101 (10), St. Margaret at Hummingbird Hwy. Guatemala. Izabal Department: GTW 13724 d (1), Livingston. Three additional specimens of this species, UF 8290, are labeled as “mouth of cave, Mount Palo, Honduras.” This probably refers to British Honduras, now Belize, but this site has not been located. Description. Shell conical, moderately high-spired, thin, translucent, with a waxy appearance. Smallest adult specimen seen 18.7 mm in length, largest 28.9 mm, average 22.0 mm (decollate). Protoconch usually lost as adult, 1.5 prominent, rounded, pale whorls. Teleoconch of 4.5–5 rounded whorls. Umbilicus nearly occluded by outer lip. Spiral sculpture of numerous faint, crowded low cords, slightly stronger in the umbilicus. Axial sculpture of numerous microscopic fine lines that render the shell microscopically decussate. Most specimens with axial hairline stress marks or fractures; others have repaired cracks to the shell. Suture strongly indented, not channeled. Tufts absent but the axial lamellae may render the suture microscopically serrate. Aperture nearly circular. Inner lip present or absent, smooth, narrowly exserted. Outer lip strongly lamellate, widely reflected perpendicular to whorl, evenly expanded, except much narrower facing umbilicus, scarcely or not at all auriculate posteriorly, widely adnate to previous whorl or rarely narrowly solute (fig. 13 M). Base color dingy white to pale orange, first teleoconch whorl reddish-orange in some specimens. Unicolor or with wide, spiral, interrupted brown bands, bands most conspicuous on anterior half of shell. Outer lip white with bold, radiating brown rays on both faces of peristome. Inside of aperture brownish-orange or white with the outer pattern showing through. Operculum paucispiral, with a thick reflected plate composed of numerous recurved lamellae. Radula and anatomy unknown. Variation in specimens. Specimens vary in the height of the spire and the degree and intensity of the color patterns. Comparison with other species. This species can be confused only with H. kuesteri, from which it differs in its larger size (average length = 22 mm in H. gruneri, 15 mm in H. kuesteri) and the smooth, waxy appearance of the shell. Remarks. See “Remarks” under H. kuesteri. Reeve (1863 b), text to pl. 9, fig. 68, adequately described this unusual species: “Of a peculiar dull, delicately transparent substance, faintly sculptured.” The shells of most specimens are so thin that they show evidence of more or less continuous damage in the form of fracture and stress lines. This is the largest annulariid in Central America. Often lumped with H. kuesteri in collections, it is clearly a distinct species. It co-occurs with H. kuesteri but does not occupy as great a range. Original description (translated here from Latin). Cyclostoma gruneri Pfeiffer, 1846. “Shell perforate, ovate-oblong, decollate, thin, crowded spirals and weak striae, crowded longitudinal lines, more or less decussate, pale yellowish-brown; 4 convex whorls, last brown banded below the periphery, near open umbilicus brown spotted; suture average, nearly simple; aperture subcircular; peristome double, inner erect, acutely exserted, outer widely fringed, a little concave, interrupted at penultimate whorl, formed into crowded radiations on both sides.” 21 mm. Original description (translated here from Latin). Cyclostoma radiosum Morelet, 1849. “Shell swollenpyramid, perforate, very numerous decussations, translucent, pale yellowish-brown, red interrupted lines saturate the final whorl, base colored with diverging rays; spire acuminate-turret, more frequently truncated; 8 rather convex whorls, last swollen; aperture rotund-oval, pretty shining bands; peristome expanded, concave, undulatelamellate, top upper half appressed; lip thin, acute, generally fimbriated towards the umbilicus.” 20 mm. Etymology. Cyclostoma gruneri Pfeiffer, 1846: Type specimen from the collection of “Herrn Konsul Gruner zu Bremen.” Cyclostoma radiosum Morelet, 1849: L. radiosus —radiant.Published as part of Watters, G. Thomas, 2014, A revision of the Annulariidae of Central America (Gastropoda: Littorinoidea), pp. 301-350 in Zootaxa 3878 (4) on pages 310-313, DOI: 10.11646/zootaxa.3878.4.1, http://zenodo.org/record/25270
Plekocheilus (Aeropictus) veranyi Pfeiffer 1848
No full textPlekocheilus (Aeropictus) veranyi (Pfeiffer, 1848) Bulimus veranyi Pfeiffer 1848 a: 230. Type locality: Venezuela, Edo. Mérida, Chachopo. Lectotype BMNH 1975297 (Breure 1978). Plekocheilus (Aeropictus) veranyi (Pfeiffer); Tello 1975: 201. Plekocheilus veranyi (Pfeiffer); Richardson 1995: 323 (references, synonymy; see remarks). Plekocheilus (Orcesiellus) succinoides [sic] (Petit); Tello 1975: 201. Bulimus scytodes Pfeiffer 1853: 256. Type locality: Andes of Colombia. Type material: not located. Material. Venezuela, Barinas, Serranía de Santo Domingo, Jackson Colln, 3000 ft [~ 1000 m, in error?]: DMNH 148721, USNM 109523 (Gabaldon leg., 3000 m); Mérida, Chachopo: BMNH; between Chachopo and Timote, C. Beets leg./ 1953: RMNH; Mérida, Jackson Colln: DMNH 160801;?Mérida, Escorial Mountains, A. Gabaldon & sons leg.: USNM 206502 (8400 ft [~ 2520 m]), USNM 206504 (9600 ft [~ 2880 m]); Glorial: DMNH 141740; “Mérida:” UMMZ 147737 (ex Rolle); “Menda” (sic): UMMZ 147736, 242815;?Miranda, Caracas, ex M.L. Jaume: CMC C 13777.?, San Domingo: UMMZ 242814 (Marsh Colln), UMMZ 147735; “ Venezuela:” CMC C 11004 –11006, USNM 109526; New Granada: ANSP 66405, ANSP 66408, BMNH (ex Cuming), ZMUZ 511641 [not seen], ZMUZ 511642 [not seen]. Altitudinal range. The localities reported here range between 2520 and 3000 m (see remarks). Remarks. The date of first publication mentioned by Richardson (1995) is erroneous. He cited “ 1847 Philippi, Abbild. Beschr. neuer Conchyl. 3: 20, pl. 8 figs 5, 9 (1851)”. However, P. veranyi is mentioned on page 36, under the heading “ Bulimus. Tab. VIII. Januar 1849.” Thus the first valid publication was in Pfeiffer (1848 a). Of the taxa grouped under this species by Richardson (1995: 324), we consider P. cathcartiae and P. quadricolor to be distinct species. This species is very similar to P. delicatus, but differs in being decidedly smaller. Colombian material, labeled as P. veranyi, should all be considered P. delicatus. Two reasons lead us to believe that the altitude of DMNH 148721 (3000 ft) may be in error: (1) Another lot from the same location (USNM 109523) is clearly labeled with an elevation of 3000 meters; (2) All known species of the subgenus Aeropictus, similar to P. succineoides, are known only from high elevations, mainly páramo (i.e., 2500 m and above); if correct, 3000 ft would be by far the lowest elevation known for any species in this group, which we consider unlikely. We have been unable to trace the localities “Glorial” and “Escorial Mountains;” the latter, may refer to a location near Páramo El Escorial (~ 3000 m), or near the town of El Escorial (~ 3100 m), both within the Sierra Nevada de Mérida. Tello (1975) included P. succinoides [sic] in his list of Venezuelan land snails (cf. Weyrauch), apparently as a misinterpretation of a portion of Weyrauch’s (1967) description of the subgenus Orcesiellus. Contrary to Tello (1975: 201), we consider it likely that the species mentioned from Mérida by this author is P. veranyi (Pfeiffer).Published as part of Borrero, Francisco J. & Breure, Abraham S. H., 2011, The Amphibulimidae (Mollusca: Gastropoda: Orthalicoidea) from Colombia and adjacent areas, pp. 1-59 in Zootaxa 3054 on page 12, DOI: 10.5281/zenodo.27889
Adaptive user assistance in virtual reality shopping
No full textThis dissertation is comprised of five publications in the domain of adaptive user assistance in virtual reality shopping:
Weiß, T., Pfeiffer, J. and Pfeiffer, T. (2024). "Early Bird – Predict healthy product choices in virtual commerce". ECIS 2024 Proceedings. 3.
Weiß, T. and Pfeiffer, J. (2024). Consumer decisions in virtual commerce: Predict good help-timing based on cognitive load. Journal of Neuroscience, Psychology, and Economics, 17(2), 119.
Weiß, T., Merkl, L., & Pfeiffer, J. (2023). Customer decision-making processes revisited: insights from an eye tracking and ECG study using a hidden Markov model. In NeuroIS Retreat (pp. 221-230). Cham: Springer Nature Switzerland.
Weiß, T., Eilks, A., Pfeiffer, J., Putze, F., and Schultz, T. (2024). "Real agents in virtual commerce". Working paper.
Weiß, T., Pfeiffer, J., and Meißner, M. (2024). "Adaptive product comparison assistance in virtual reality". Working paper.Deutsche Forschungsgemeinschaft (DFG); ROR-ID:018mejw6
Parachondria (Chondropomorus) petitianus Pfeiffer 1850
No full textParachondria (Chondropomorus) petitianus (Pfeiffer, 1850) Figures 2 P–V, 5 A Type material. NHMUK 42 / 10 (3), syntypes. Label reads " Type set - probable type in tube (13mm), photo - photo sent to Bartsch 1938." Type locality. “ in insula Haiti.” Restricted here to 13 km NE of Pizarrette, San Cristóbal Province, Dominican Republic. Type figured. Pfeiffer, 1854, pl. 37, figs. 23 and 24 are probably the figured type. Cresonymy. Cyclostoma petitianum Pfeiffer, 1850: 78 –79; Pfeiffer, 1854: 277–278, pl. 37, figs. 23, 24; Watters, 2006: 399. Chondropoma petitianum (Pfeiffer, 1850). Pfeiffer, 1851: 173; Pfeiffer, 1852 a: 291; Pfeiffer, 1852 b: 45; Adams & Adams, 1858: 295; Hjalmarson & Pfeiffer, 1858: 142; Bland, 1861: 355; Reeve, 1863: pl. 5, fig. 34; Pfeiffer, 1865: 155; Pfeiffer, 1876: 196; Kobelt, 1880: 277; Weinland, 1880: 346; Crosse, 1891: 174. Chondropoma (Chondropomorus) petitiana (Pfeiffer, 1850). Henderson & Bartsch, 1920: 61; Clench & Aguayo, 1937: 65 –66. Chondropoma (Chondropomorus) petitianum (Pfeiffer, 1850). Pilsbry, 1933: 123 –124. Chondropoma (Chondropomorus) petitianum petitianum (Pfeiffer, 1850). Bartsch, 1946: 18, 20, pl. 2, fig. 2. Parachondria (Parachondria) petitianus petitianus (Pfeiffer, 1850). Watters, 2006: 46. Chondropomorus petitianus petitianus (Pfeiffer, 1850). Watters, 2006: 399. Distribution and habitat. Generally below 300 m on the southeastern edge of the Paralta Belt, a series of Eocene–Oligocene sedimentary sequences of the southeastern Cordillera Central. UF 216729 and UF 216729 refer to two localities in San Cristóbal Province that have not been located. However, two localities of the same name occur in Monte Plata Province. If the province name is actually Monte Plata then this species continues along the eastern edge of the Cordillera Central to the Cordillera Oriental but additional collections are needed to establish this extension. Found under leaf litter and talus, on limestone ridges in mesic, canopied canyons, forests, and in scrub thickets. Material examined (32 specimens). Dominican Republic. UF 23219 (2), 70 m, 13 km NE of Pizarrette, San Cristóbal Province; UF 216420 (1), UF 216727 (6), 110 m, 13 km NNW of Pizarrette, Peravia Province; UF 216724 (1), 310 m, 3 km N of El Recodo, Peravia Province; UF 216563 (1), UF 216564 (3), 310 m, 3 km N of El Recodo, Peravia Province; UF 216729 (1), 185 m, 10 km SW of Trinidad, Monte Plata Province; UF 216733 (2), 220 m, 13 km NW of Sabana Grande de Boya, Monte Plata Province; UF 216747 (4), 3 km E of El Majagual, San Cristóbal Province; UF 216740 (11), 4 km E of El Majagual, San Cristóbal Province; UF 216748 (1), 5 km E of El Majagual, San Cristóbal Province; UF 216746 (1), 1 km W of El Majagual, San Cristóbal Province. Redescription. Shell small for genus, solid, opaque, high-spired, elongate conic. Maximum adult size: 15.2 mm, decollate. Minimum adult size: 10.9 mm, decollate. Adult shell decollated, protoconch lost in examples seen; Bartsch (1946) gave 2 + whorls for protoconch. Teleoconch with 5 remaining whorls in decollated shells. Axial sculpture of final whorl of numerous (ca. 180) minute, very fine threads separated by same width as threads. Shell with regularly spaced growth stoppage marks, axial threads preceding marks often microscopic and densely packed. Spiral sculpture of final whorl outside of umbilicus obsolete, visible only as weak, axially elongated beads where they cross axial threads. Overall sculpture nearly microscopic, white axial beads give frosted appearance. Umbilicus bounded by 4–6 very weak cords, smooth within. Suture very narrow, not channeled. Tufts composed of 1–3 only slightly enlarged axial threads that are strongest just preceding each growth mark. Aperture oval, lip double. Inner lip weakly expanded, not exserted, fused to outer lip. Outer lip evenly expanded, narrower facing umbilicus, adnate to barely solute with previous whorl. Weak posterior auricle present. Color pattern complex and variable. Base color tan. Growth marks with axially aligned brown or tan zig-zags, spots, or diagonal marks. At least one more or less continuous brown band bounding umbilicus. Tufts and sculpture white. “Operculum paucispiral with the nucleus half-way between subcentral and marginal” fide Bartsch (1946: 18); lacking in all specimens examined here. Variation in specimens. Specimens are remarkably uniform in all characteristics. Comparison with other species. From the other high-spired species it has much finer sculpture than either P. trachydermus or P. silvaticus. From P. gnotus it differs in having better developed sutural tufts and in having even finer sculpture (ca. 120 axial threads in P. gnotus vs. ca. 180 axial threads in P. petitianus). Remarks. Bartsch (1946) divided this species into five widely scattered subspecies: Chondropoma p. costatum Weinland, 1880, from Samaná Bay; C. p. dominicum Bartsch, 1946, from Puerto Plata (both = P. trachydermus Pilsbry, 1933), C. p. dessalinesi Bartsch, 1946, from Thomazeau, Haiti, “ C. p. hispaniolae Clench & Aguayo, 1937 ” (non Clench & Aguayo, 1937 = P. arcisensis), from Milot, Haiti; and the nominate subspecies C. p. petitianum (Pfeiffer, 1850) from “ in insula Haiti.” Based on their shell morphology, their isolation, and the narrow ranges of similar species, I believe these are distinct species. Original description. Pfeiffer (1850: 78–79) (translated here from Latin). “Shell scarcely subperforate, oblong-turrited, truncate, spiral elevated lines about equally distant and crowded plications cross over that sculpture, a little shining, white, brown marbling and broken bands; suture separate and irregularly crenulated; 5 – 5 ½ slightly convex whorls, slowly becoming larger, the last not solute; aperture subvertical, oval; peristome double, inner one short, outer one broadly expanded, brown-spotted, top subauriculate, cut off from previous whorl, left margin narrow.—Operculum membraneous, brown, paucispiral.” Etymology. Sauveur Abel Aubert Petit de la Saussaye (1792–1870), French conchologist, editor of the Journal de Conchyliologie (1850–1853).Published as part of Watters, G. Thomas, 2016, Review of the Hispaniolan Parachondria (Chondropomorus) complex (Gastropoda: Littorinoidea: Annulariidae), pp. 245-275 in Zootaxa 4127 (2) on pages 256-257, DOI: 10.11646/zootaxa.4127.2.2, http://zenodo.org/record/27177
- …
