1,151 research outputs found
Acute lung injury in paediatric intensive care: course and outcome
Introduction: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) carry a high morbidity and mortality (10-90%). ALI is characterised by non-cardiogenic pulmonary oedema and refractory hypoxaemia of multifactorial aetiology [1]. There is limited data about outcome particularly in children. Methods This retrospective cohort study of 85 randomly selected patients with respiratory failure recruited from a prospectively collected database represents 7.1% of 1187 admissions. They include those treated with High Frequency Oscillation Ventilation (HFOV). The patients were admitted between 1 November 1998 and 31 October 2000. Results: Of the 85, 49 developed acute lung injury and 47 had ARDS. There were 26 males and 23 females with a median age and weight of 7.7 months (range 1 day-12.8 years) and 8 kg (range 0.8-40 kg). There were 7 deaths giving a crude mortality of 14.3%, all of which fulfilled the Consensus I [1] criteria for ARDS. Pulmonary occlusion pressures were not routinely measured. The A-a gradient and PaO2/FiO2 ratio (median + [95% CI]) were 37.46 [31.82-43.1] kPa and 19.12 [15.26-22.98] kPa respectively. The non-survivors had a significantly lower PaO2/FiO2 ratio (13 [6.07-19.93] kPa) compared to survivors (23.85 [19.57-28.13] kPa) (P = 0.03) and had a higher A-a gradient (51.05 [35.68-66.42] kPa) compared to survivors (36.07 [30.2-41.94]) kPa though not significant (P = 0.06). Twenty-nine patients (59.2%) were oscillated (Sensormedics 3100A) including all 7 non-survivors. There was no difference in ventilation requirements for CMV prior to oscillation. Seventeen of the 49 (34.7%) were treated with Nitric Oxide including 5 out of 7 non-survivors (71.4%). The median (95% CI) number of failed organs was 3 (1.96-4.04) for non-survivors compared to 1 (0.62-1.62) for survivors (P = 0.03). There were 27 patients with isolated respiratory failure all of whom survived. Six (85.7%) of the non-survivors also required cardiovascular support.Conclusion: A crude mortality of 14.3% compares favourably to published data. The A-a gradient and PaO2/FiO2 ratio may be of help in morbidity scoring in paediatric ARDS. Use of Nitric Oxide and HFOV is associated with increased mortality, which probably relates to the severity of disease. Multiple organ failure particularly respiratory and cardiac disease is associated with increased mortality. ARDS with isolated respiratory failure carries a good prognosis in children
Probing Classifiers are Unreliable for Concept Removal and Detection
Neural network models trained on text data have been found to encode
undesirable linguistic or sensitive concepts in their representation. Removing
such concepts is non-trivial because of a complex relationship between the
concept, text input, and the learnt representation. Recent work has proposed
post-hoc and adversarial methods to remove such unwanted concepts from a
model's representation. Through an extensive theoretical and empirical
analysis, we show that these methods can be counter-productive: they are unable
to remove the concepts entirely, and in the worst case may end up destroying
all task-relevant features. The reason is the methods' reliance on a probing
classifier as a proxy for the concept. Even under the most favorable conditions
for learning a probing classifier when a concept's relevant features in
representation space alone can provide 100% accuracy, we prove that a probing
classifier is likely to use non-concept features and thus post-hoc or
adversarial methods will fail to remove the concept correctly. These
theoretical implications are confirmed by experiments on models trained on
synthetic, Multi-NLI, and Twitter datasets. For sensitive applications of
concept removal such as fairness, we recommend caution against using these
methods and propose a spuriousness metric to gauge the quality of the final
classifier
Computational Methods for Medical and Cyber Security
Over the past decade, computational methods, including machine learning (ML) and deep learning (DL), have been exponentially growing in their development of solutions in various domains, especially medicine, cybersecurity, finance, and education. While these applications of machine learning algorithms have been proven beneficial in various fields, many shortcomings have also been highlighted, such as the lack of benchmark datasets, the inability to learn from small datasets, the cost of architecture, adversarial attacks, and imbalanced datasets. On the other hand, new and emerging algorithms, such as deep learning, one-shot learning, continuous learning, and generative adversarial networks, have successfully solved various tasks in these fields. Therefore, applying these new methods to life-critical missions is crucial, as is measuring these less-traditional algorithms' success when used in these fields
Computational intelligence approaches to robotics, automation, and control [Volume guest editors]
No abstract available
Control of high harmonic generation by manipulation of field parameters
?High harmonic generation is a well established technique to investigate the structure
and the inner dynamics of atoms and molecules. This thesis describes how the generating
field parameters can be manipulated to extend the limits imposed on the technique
by the use of traditional laser sources. In this field, with traditional source we mean
high intensity, linearly polarised laser pulses at 800 nm.
The first parameter to be investigated is the wavelength λ of the generating beam. The
unfavourable scaling of the high harmonic yield with λ seems to suggest that high harmonic
spectroscopy of atoms and molecules should be restricted to the wavelengths that
obviate this problem, and that therefore shorter wavelength should be used. But longer
wavelengths, in the mid infrared, present a great advantage respect to shorter ones. The
maximum harmonic order that we can obtain is proportional to the ionisation potential
of the target and to the wavelength times the intensity of the beam, so a higher number
of harmonic can be produced with a longer wavelength than with short, the intensity
being equal. This becomes incredibly valuable when the specie under investigation is a
molecule with low ionisation potential.
To produce high harmonics, a linearly polarised beam is required. If ellipticity is introduced
in the beam, the harmonic signal quickly fades out, as non-linearly polarisation in
monochromatic beams switches off the mechanism at the basis of high harmonic generation.
This is not true if the polarisation of the beam is changed through the introduction
of an additional laser beam, perpendicularly polarised respect to the fundamental. In
this thesis the additional degree of freedom that this second field implies is investigated
by combining the fundamental with its second harmonic and by controlling the relative
delay of the two with sub-cycle precision. The key result is that the addition of the second
harmonic gives access to the control of the harmonic amplitude and to the time at
which the high harmonics are emitted, by simply controlling the relative phase between
the two pulses
Discover, recycle and reuse frequent patterns in association rule mining
Ph.DDOCTOR OF PHILOSOPH
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