Illustrating the Central Limit Theorem Through Microsoft Excel Simulations

Using Microsoft Excel, several interactive, computerized learning modules are developed to demonstrate the Central Limit Theorem. These modules are used in the classroom to enhance the comprehension of this theorem. The Central Limit Theorem is a very important theorem in statistics, and yet because it is not intuitively obvious, statistics students often have difficulty accepting it. Nevertheless, understanding this theorem is essential because of its importance in statistical inference

A Microsoft Excel Simulation Illustrating The Central Limit Theorems Appropriateness For Comparing The Difference Between The Means Of Any Two Populations

Using Microsoft Excel, several interactive, computerized learning modules are developed to illustrate the Central Limit Theorems appropriateness for comparing the difference between the means of any two populations. These modules are used in the classroom to enhance the comprehension of this theorem as well as the concepts that provide the foundation for inferences involving the comparison of two population means

Stakeholder perspectives on the development of a virtual clinic for diabetes care : qualitative study

Background: The development of the Internet has created new opportunities for health care provision, including its use as a tool to aid the self-management of chronic conditions. We studied stakeholder reactions to an Internet-based “virtual clinic,” which would allow people with diabetes to communicate with their health care providers, find information about their condition, and share information and support with other users. Objective: The aim of the study was to present the results of a detailed consultation with a variety of stakeholder groups in order to identify what they regard as the desirable, important, and feasible characteristics of an Internet-based intervention to aid diabetes self-management. Methods: Three focus groups were conducted with 12 people with type 1 diabetes who used insulin pumps. Participants were recruited through a local diabetes clinic. One-on-one interviews were conducted with 5 health care professionals from the same clinic (2 doctors, 2 nurses, 1 dietitian) and with 1 representative of an insulin pump company. We gathered patient consensus via email on the important and useful features of Internet-based systems used for other chronic conditions (asthma, epilepsy, myalgic encephalopathy, mental health problems). A workshop to gather expert consensus on the use of information technology to improve the care of young people with diabetes was organized. Results: Stakeholder groups identified the following important characteristics of an Internet-based virtual clinic: being grounded on personal needs rather than only providing general information; having the facility to communicate with, and learn from, peers; providing information on the latest developments and news in diabetes; being quick and easy to use. This paper discusses these characteristics in light of a review of the relevant literature. The development of a virtual clinic for diabetes that embodies these principles, and that is based on self-efficacy theory, is described. Conclusions: Involvement of stakeholders is vital early in the development of a complex intervention. Stakeholders have clear and relevant views on what a virtual clinic system should provide, and these views can be captured and synthesized with relative ease. This work has led to the design of a system that is able to meet user needs and is currently being evaluated in a pilot study

New microplanktonic biostratigraphy and depositional sequences across the Middle-Late Eocene and Oligocene boundaries in eastern Jordan

The first detailed calcareous nannofossil and planktonic foraminiferal biostratigraphic and integrated lithofacies analyses of the Eocene–Oligocene transition at the Qa’ Faydat ad Dahikiya area in the Eastern Desert of Jordan, on the border with Saudi Arabia, is presented. Three calcareous nannofossil zones namely: Discoaster saipanensis (NP17), Chiasmolithus oamaruensis (NP18) and Ericsonia subdisticha (NP21), and three planktonic foraminiferal zones: upper part of Truncorotaloides rohri (E13), Globigerinatheka semiinvoluta (E14) and Cassigerinella chipolensis/ Pseudohastigerina micra (O1) are identified. Calcareous nannofossil bioevents recorded in the present study show numerous discrepancies with the Standard biostratigraphic zonal schemes to detect the Middle/Upper Eocene boundary (e.g. the highest occurrences (HOs) of Chiasmolithus solitus, C. grandis, and lowest occurrences (LOs) of C. oamaruensis, Isthmolithus recurvus are not considered reliable markers for global correlation). The Middle/Upper Eocene boundary occurs in the current study above the extinctions of large muricate planktonic foraminifera (large Acarinina and Truncorotaloides spp.) which coincide within the equivalent calcareous nannofossil NP18 Zone. These microplanktonic bioevents seem to constitute more reliable markers for the base of the Upper Eocene in different provinces. The uppermost portion of the Middle Eocene is characterized by an observed drop in faunal content and, most likely, primarily denotes the effect of the major fall in eustatic sea level. A major unconformity (disconformity) marked by a mineralized hardground representing a lowstand is recorded in the present study at the Eocene–Oligocene transition that reveals an unexpected ca. 2.1 Myr duration, separating Eocene (NP18/E14 zones) from Oligocene (NP21/O1 zones). Furthermore, the microfossil turnover associated with a rapid decline of the microfossil assemblages shows a distinct drop in diversity and abundance towards the Eocene/Oligocene unconformity and is associated with a sharp lithological break marked, at the base, by a mineralized hardground representing a major sequence boundary. These bioevents, depositional sequences and the depositional hiatus correlate well with different parts of the Arabian and African plates, but the magnitude of the faunal break differs from place to place as a result of intraplate deformation during the regional Oligocene regression of Neo-Tethys on the northern Arabian Plate. The presence of the Lower Oligocene shallow-marine calcareous planktonic assemblages in the study area indicate that communication between the eastern and western provinces of the western Neo-Tethys region still existed at this time

Diamicton from the Vale of Pickering and Tabular Hills, north-east Yorkshire: evidence for a Middle Pleistocene (MIS 8) glaciation?

Diamicton deposits (up to 6.90 m thick) in the Vale of Pickering and the Tabular Hills (North York Moors) have been confirmed by cored boreholes. The diamicton is interpreted as glacial till with a matrix consisting predominantly of grey-brown, yellow-brown and dark grey, stiff to very stiff clay and sandy clay with occasional thin beds of laminated sand and clay. Sub-rounded to sub-angular erratic clasts were sourced predominantly from local Upper Jurassic Corallian Group bedrock exposed in the southern part of the North York Moors. Clasts include well-rounded, pebbles of Jurassic sandstone, mudstone and sparse Jurassic coal derived from outcrops on the North York Moors. Fragments of underlying Upper Jurassic mudstone bedrock form the predominant clasts in the lower part of the till. The paucity of exotic clasts and a local derivation suggests a relatively small glacier – perhaps a temperate-plateau ice-field, was established on the Tabular Hills. The glacier subsequently advanced southwards to the Vale of Pickering depositing locally derived subglacial traction till at the base, passing up to lodgement till. Local preservation of the degraded till outcrops in the Vale of Pickering, the overconsolidated nature of the clay till matrix, striated pebbles and the presence of sub-rounded pebbles suggests deposition during a glacial cold stage post-MIS 12 (Anglian) and pre-MIS 2 (Devensian). A tentative Middle Pleistocene MIS8 age is proposed, possibly coeval, but not coincident, with the Basement Till (Bridlington Member) of the Holderness coast and the Wragby Till of central and eastern England

Integrated microfossil biostratigraphy, facies distribution, and depositional sequences of the upper Turonian to Campanian succession in northeast Egypt and Jordan

Six upper Turonian to Campanian sections in Egypt (Sinai) and Jordan were studied for their microfossil biostratigraphy (calcareous nannofossils and planktonic foraminifera), facies distribution and sequence stratigraphic frameworks. Carbonate (mostly chalk) and chert lithofacies dominate the basinward northern sections passing laterally and vertically to mixed carbonate/siliciclastic lithofacies towards the shoreline in the southeast. Twenty-six lithofacies types have been identified and grouped into six lithofacies associations: littoral siliciclastic facies belt; peritidal carbonate; intertidal carbonate platform/ramp; high-energy ooidal shoals and shelly biostromes; shallow subtidal; and pelagic facies association. The following calcareous nannofossil biozones were recognized: Luianorhabdus malefomis (CC12) (late Turonian), Micula staurophora (CC14) (early Coniacian), Reinhardtites anthophorus (CC15) (late Coniacian), Lucianorhabdus cayeuxii (CC16) (early Santonian) and Broinsonia parca parca (CC18) (Campanian). Equivalent planktonic foraminifera zones recognized are: Dicarinella concavata (Coniacian), the lower most part of Dicarinella asymetrica (earliest Santonian) and Globotruncanita elevata (early Campanian). The integrated zonation presented here is considered to provide higher resolution than the use of either group alone. The absence of calcareous nannofossil biozones CC13 and CC17 in most of the studied sections, associated with regional vertical lithofacies changes, indicates that recognition of the Turonian/Coniacian and Santonian/Campanian stage boundary intervals in the region have been hampered by depositional hiatuses at major sequence boundaries resulting in incomplete sections. These disconformities are attributed to eustatic sea-level fluctuations and regional tectonics resulting from flexuring of the Syrian Arc fold belt. The Coniacian to Santonian succession can be divided into three third-order depositional sequences, which are bounded by four widely recognized sequence boundaries

Cambrian stratigraphy of Jordan

The lower and middle Cambrian succession (Ram Group) in Jordan is described in lexicon-style format to document an important phase of Earth history following the uplift and erosion of the Arabian-Nubian Shield (Aqaba Complex) during the late Neoproterozoic, and younger, but more localised, intrusive and volcanic/ volcaniclastic activity that formed the Araba Complex. The early Cambrian Ram Unconformity (ca. 530 Ma) marks the base of a predominantly fluvial siliciclastic succession derived from rapidly eroding Neoproterozoic (including Ediacaran) basement rocks, but includes a brief, but biostratigraphically significant, sequence of marine siliciclastics and carbonates, the early mid-Cambrian Burj Formation. Rapid uplift and erosion of the granitoid basement (Arabian-Nubian Shield or ANS) resulted in a peneplanation of the Aqaba Complex over millions of years duration (latest Neoproterozoic to Cambrian) in the Southern Desert of Jordan. Early Cambrian pebbly sandstones and locally derived conglomerates (Salib Formation) were deposited on an alluvial plain by high velocity-high discharge, northward flowing (NNE to NNW) braided rivers, characterised by trough crossbedding and erosive tabular sets. Brief, and rare, marine influence is represented, locally, by thin Skolithos-burrowed sandstones. A regional sea-level rise in the early mid-Cambrian marks a major marine transgressive-regressive cycle and southward thinning carbonate-siliciclastic wedge (Burj Formation) widely present in the subsurface across the Arabian Platform. During deposition of this transgressive marine sequence the palaeoshoreline was oriented WNW-ESE in southern Jordan. The transgressive phase (TST) is represented by tidal-dominated siltstones and fine-grained sandstones (Tayan Member) containing a diverse Cruziana/Rusophycus ichnofaunal assemblage. The overlying carbonate unit (Numayri Member) represents the highstand (HST) and maximum marine flooding surface (MFS), and comprises a carbonate ramp sequence of shelly wackestone, packstone and grainstone with ooids and oncolites, and a diverse shelly fauna including trilobites, brachiopods and hyolithids. A return to regressive tidal-influenced sandstone and siltstone (along with thin carbonates in central Jordan) (Hanneh Member) represents a regressive wedge (RST) deposited in response to renewed uplift of the ANS. Trilobites, represented by the Kingaspis campbelli and Redlichops faunules, suggest a biostratigraphical age of early mid-Cambrian for the carbonate MFS, which equates approximately to the base of the Cambrian Series 3 (Stage 5). This event probably represents the Cambrian marine flooding surface Cm20 (approximate geochronological age of 509 to 505 Ma). South of Feinan, in the Wadi Araba, the carbonates pass laterally to marine sandstone (Abu Khusheiba Sandstone) with extensive Skolithos burrows and Cruziana/Rusophycus traces. Traced southwards (palaeohinterland) the marine influence diminishes, so that the Burj/Abu Khusheiba units are absent in the Southern Desert

Dissipation and mixing during the onset of stratification in a temperate lake, Windermere

Acoustic Doppler Current Profilers and chains of temperature sensors were used to observe the spring transition to stable stratification over a 55 day period in a temperate lake. Observations of the flow structure were complemented by measurements of dissipation, based on the Structure Function method, near the lake bed and in the upper part of the water column. During complete vertical mixing, wind-driven motions had horizontally isotropic velocities with roughly equal barotropic and baroclinic kinetic energy. Dissipation was closely correlated with the wind-speed cubed, indicating law of the wall scaling, and had peak values of ~1 x 10-5.5 W kg-1 at 10 m depth during maximum wind forcing (W~ 15 m s-1). As stratification developed, the flow evolved into a predominantly baroclinic regime dominated by the first mode internal seiche, with root mean square (rms) axial flow speeds of ~2-3 cm-1; ~ 2.5-times the transverse component. At 2.8 m above the bed, most of the dissipation occurred in a number of strong maxima coinciding with peaks of near-bed flow. In the pycnocline, dissipation was low most of the time, but with pronounced maxima (reaching ~1 x 10-5 W kg-1) closely related to the local velocity shear. The downward diffusive heat flux across the pycnocline over 27.5 days accounted for ~ 70% of the temperature rise in the water column below. Total lake kinetic energy increased by a factor of 3 between mixed and stratified regimes, in spite of reduced wind forcing, indicating less efficient damping in stable conditions

A double-blind placebo controlled experimental study of nicotine: II - Effects on response inhibition and executive functioning

Rationale: Smokers may show abnormal functioning in prefrontal cortex during acute abstinence, reflecting deficient activity in mesocorticolimbic circuitry. Cognitive correlates of this putatively include impaired response inhibition and other aspects of executive functioning. Objectives: To investigate whether inhibitory control and other executive functions in smokers are impaired during acute abstinence relative to post-nicotine. Methods: 145 smokers were tested twice following overnight abstinence, once after nicotine and once after placebo lozenges (order counterbalanced, double-blind), on: an antisaccade task; a Continuous Performance Task (CPT); a delayed response Spatial Working Memory (SWM) task; and a verbal fluency test. Results: Compared with placebo, nicotine was associated with better inhibitory control on the antisaccade task and fewer impulsive responses to filler stimuli (motor errors) on the CPT; at the first assessment only, nicotine also reduced impulsive responses to ‘catch’ stimuli on the CPT. However, it did not affect CPT response bias (an index of impulsive vs. cautious decision-making), spatial working memory, or verbal fluency. Conclusions: Smoking abstinence appears to be associated with difficulty in inhibiting prepotent motor responses, and nicotine to attenuate this difficulty. However, more ‘cognitive’ forms of inhibitory control (e.g. decision-making) and the other aspects of executive function tested here appear to be unaffected