200,004 research outputs found
Using Perl for Statistics: Data Processing and Statistical Computing
No full textIn this paper we show how Perl, an expressive and extensible high-level programming language, with network and ob ject-oriented programming support, can be used in processing data for statistics and statistical computing. The paper is organized in two parts. In Part I, we introduce the Perl programming language, with particular emphasis on the features that distinguish it from conventional languages. Then, using practical examples, we demonstrate how Perl's distinguishing features make it particularly well suited to perform labor intensive and sophisticated tasks ranging from the preparation of data to the writing of statistical reports. In Part II we show how Perl can be extended to perform statistical computations using modules and by "embedding" specialized statistical applications. We provide example on how Perl can be used to do simple statistical analyses, perform complex statistical computations involving matrix algebra and numerical optimization, and make statistical computations more easily reproducible. We also investigate the numerical and statistical reliability of various Perl statistical modules. Important computing issues such as ease of use, speed of calculation, and efficient memory usage, are also considered.
An analysis of the PERL Magnetic Resonance Imaging theory and implementation
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaf 32).The goal of PERL MRI in its most basic form is single shot imaging without the need to rapidly switch gradients to encode spatial information into the signal. PERL MRI incorporates the application of the PERL field into the standard spin echo sequence following the excitation of spins, creating an initial phase pattern that causes echoes to form in the signal in the presence of a constant readout gradient. The echo train that occurs can be sampled and decoded into image data using reconstruction methods that are not discussed in this paper. The theoretical analysis of PERL MRI that will be discussed verifies the mathematical basis for the formation of a periodic signal resulting from cyclical coherence of the spins within a homogeneous sample. Theory also indicates a significant reduction in the maximum amount of coherence present in the PERL signal as compared to total coherence that occurs at the center of k-space, indicating that SNR may suffer with this technique. The effects of specific design parameters on the field generated by a proposed PERL coil design layout is discussed, and an experimental design is presented. The experimental PERL coil produces an approximation of the PERL field over a limited spatial region at the center of the coil structure. The PERL MRI pulse sequence was implemented by interfacing the experimental PERL coils to the slice selection gradient channel of a TecMag MRI console. Experiments were conducted using water phantom with varying amounts of PERL prephasing and readout gradient strengths, in an attempt to obtain data confirming the effects of the PERL imaging parameters on the PERL signal. These experiments were inconclusive as to the formation of a PERL echo train, but some form of cyclical coherence appeared to result. The evidence does not suggest that the PERL approach is robust when implemented with the experimental apparatus used in these experiments. Additional experiments are proposed, and possible explanations for the non-ideality of the experimental results are presented
PERL, un freeware de éxito
No full textPara que es el programa PERL, su funcionamiento su mercado de programación, los programas con quien compite m ventaja
Nosokomiale Pneumonie
No full textPneumonia occurring more than 48 h after induction of mechanical ventilation is called ventilator-associated pneumonia (VAP). VAP is the most common nosocomial infection in intensive care medicine and is associated with prolonged intensive care and hospital stay and a higher mortality. The main pathomechanism for development of ventilator-associated pneumonia is not so much the mechanical ventilation per se but more the pathogens passing along the tube towards the lungs. Avoidance of tracheal intubation, strict hygienic measures, reduction of oropharyngeal colonization and the avoidance of microaspiration are the most promising prevention strategies. Therapeutic success in treatment of VAP is coupled to an early diagnosis and therapy. Suspicion of pneumonia is based on clinical and radiologic criteria. Biomarkers and microbiological findings are important for follow-up and reevaluation of the suspected diagnosis
Perl Script
No full textThis Perl script enables you to extract the longest open reading frame (ORF) from nucleatide sequence
Perioperative thermal management
No full textPerioperative hypothermia can influence clinical outcome negatively. It triples the incidence of adverse myocardial outcomes, significantly increases perioperative blood loss, significantly augments allogenic transfusion requirements, and increases the incidence of surgical wound infections. The major causes are redistribution of heat from the core of the body to the peripheral tissues and a negative heat balance. Adequate thermal management includes preoperative and intraoperative measures. Preoperative measures, e.g., prewarming, enhance heat content of the peripheral tissues, thereby reducing redistribution of heat from the core to the peripheral tissues after induction of anesthesia. Intraoperative measures are active skin surface warming of a large body surface area with conductive or convective warming systems. Intravenous fluids should be warmed when large volumes of more than 500-1000 ml/h are required. The body surfaces that cannot be actively warmed should be insulated. Airway humidification and conductive warming of the back are less efficient
PeRL: Permafrost Region Pond and Lake Database, links to ArcGIS shapefiles
No full textPonds and lakes are abundant in Arctic permafrost lowlands. They play an important role in Arctic wetland ecosystems by regulating carbon, water, and energy fluxes and providing freshwater habitats. However, ponds, i.e., waterbodies with surface areas smaller than 1.0 × 10**4 m**2, have not been inventoried on global and regional scales. The Permafrost Region Pond and Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds and lakes from modern (2002-2013) high-resolution aerial and satellite imagery with a resolution of 5 m or better. The database also includes historical imagery from 1948 to 1965 with a resolution of 6 m or better. PeRL includes 69 maps covering a wide range of environmental conditions from tundra to boreal regions and from continuous to discontinuous permafrost zones. Waterbody maps are linked to regional permafrost landscape maps which provide information on permafrost extent, ground ice volume, geology, and lithology. This paper describes waterbody classification and accuracy, and presents statistics of waterbody distribution for each site. Maps of permafrost landscapes in Alaska, Canada, and Russia are used to extrapolate waterbody statistics from the site level to regional landscape units. PeRL presents pond and lake estimates for a total area of 1.4 × 10**6 km**2 across the Arctic, about 17 % of the Arctic lowland ( < 300 m a.s.l.) land surface area. PeRL waterbodies with sizes of 1.0 × 10**6 m**2 down to 1.0 × 10**2 m**2 contributed up to 21 % to the total water fraction. Waterbody density ranged from 1.0 × 10 to 9.4 × 10**1/km². Ponds are the dominant waterbody type by number in all landscapes representing 45-99 % of the total waterbody number. The implementation of PeRL size distributions in land surface models will greatly improve the investigation and projection of surface inundation and carbon fluxes in permafrost lowlands
HBL/Perl/R scripts
No full textExample scripts (HyPhy batch language, perl) for analysing evolutionary rates and indels; R scripts for producing heatmaps from relative rate data and reconstructing the indel history over a given phylogeny after indel-coding with SeqState; includes five example data and tree files
Automated SNP genotype clustering algorithm to improve data completeness in high-throughput SNP genotyping datasets from custom arrays
No full textHigh-throughput SNP genotyping platforms use automated genotype calling algorithms to assign genotypes. While these algorithms work efficiently for individual platforms, they are not compatible with other platforms, and have individual biases that result in missed genotype calls. Here we present data on the use of a second complementary SNP genotype clustering algorithm. The algorithm was originally designed for individual fluorescent SNP genotyping assays, and has been optimized to permit the clustering of large datasets generated from custom-designed Affymetrix SNP panels. In an analysis of data from a 3K array genotyped on 1,560 samples, the additional analysis increased the overall number of genotypes by over 45,000, significantly improving the completeness of the experimental data. This analysis suggests that the use of multiple genotype calling algorithms may be advisable in high-throughput SNP genotyping experiments. The software is written in Perl and is available from the corresponding author
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