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At least 1,531 records · Page 85Linked to original sources
PubMed1994

Suicidal asphyxia by gas mask.

Antichemical warfare kits that were issued to all Israeli residents 6 months before the Gulf War included masks of various types suited to the age of the user. During the war, 10 adults died of suffocation due to mishandling of the filter of the masks despite the offil Defense Authority's repeated instructions to be cautious. These masks remained in the possession of the population after the war. We report on six cases of suicidal asphyxia incurred by donning the gas mask tightly sealed that have occurred since 1991.

Adult↗
PubMed1995

Mask lift and facial aesthetic sculpturing.

Paul Tessier started the great adventure of sculpturing the malformed face more than 30 years ago. Key procedures such as subperiosteal dissection and lifting of the facial mask, bone grafting from a cranial site of harvest, and lateral canthopexies have been utilized and have withstood the trial of time in thousands of patients. The mask lift with facial aesthetic sculpturing, a newcomer in aesthetic surgery, is an extrapolation of these craniofacial procedures. It is a different and revolutionary approach to the aging face that seeks to normalize, rejuvenate, and embellish the face through a subperiosteal lift of the facial mask and transformation of the underlying structures. Facial aesthetic sculpturing refers to the aesthetic sculpturing of the facial skeleton. It allows us to equilibrate the components of a malformed face and normalize it by osteotomies, displacements in three dimensions, and bone overgrafting; to normalize the forms of an unattractive face and to embellish it by harmonization of the skeletal volume; and to restore the forms of an aging face and to rejuvenate it by augmenting resorbed bone, reducing hypertrophic bone, and lifting the facial mask. My experience includes 350 patients operated on from 1981 to 1992, of these, 200 cases were purely aesthetic, 150 functional. The complications encountered have been few. The technique described offers an appropriate response to the different problems of aging and embellishment of a face, whether for reequilibration of osseous volumes or for sagging of soft tissues of the superior two-thirds of the face. Facial aesthetic sculpturing finds application also in some malformations and acquired deformities and in young faces with unsightly features.

Aged↗
PubMed2006

Assessment of the validity of masking in electrodiagnostic research.

OBJECTIVES: Performed by thousands of specialists and researched for >60 yrs, electrodiagnostic testing rates poorly in evidence-based guidelines in part because there are no valid masked research studies. This study assesses whether the electrodiagnostic examination can be adequately masked. DESIGN: Prospective, controlled, masked trial. A total of 150 persons aged 55-80 yrs, thought clinically to be asymptomatic (n = 32), with low back pain (n = 46), or with spinal stenosis (n = 63), underwent needle electromyography and nerve conduction studies by specialists in physical medicine and rehabilitation who were not permitted to ask any clinical information or to perform a formal examination. Examiners rated potential bias and recorded clues that might bias the examination. RESULTS: Examiners noted potential for bias in conversation in 17 and due to pain behavior in one. Half of these potential unmaskings pointed away from the correct clinical diagnosis, leaving potential for bias in <6% of the subjects. The clinical diagnosis had no relationship to electrodiagnostician rating of pain behavior in response to testing or repositioning, to limb atrophy, and to arthritis (P > 0.05 all instances). CONCLUSIONS: The electrodiagnostic examination can be successfully masked. This information will help future research in electrodiagnostics meet the criteria of evidence-based medicine.

Aged↗
PubMed2000

The Noh mask effect: vertical viewpoint dependence of facial expression perception.

Full-face masks, worn by skilled actors in the Noh tradition, can induce a variety of perceived expressions with changes in head orientation. Out-of-plane rotation of the head changes the two-dimensional image characteristics of the face which viewers may misinterpret as non-rigid changes due to muscle action. Three experiments with Japanese and British viewers explored this effect. Experiment 1 confirmed a systematic relationship between vertical angle of view of a Noh mask and judged affect. A forward tilted mask was more often judged happy, and one backward tilted more often judged sad. This effect was moderated by culture. Japanese viewers ascribed happiness to the mask at greater degrees of backward tilt with a reversal towards sadness at extreme forward angles. Cropping the facial image of chin and upper head contour reduced the forward-tilt reversal. Finally, the relationship between head tilt and affect was replicated with a laser-scanned human face image, but with no cultural effect. Vertical orientation of the head changes the apparent disposition of facial features and viewers respond systematically to these changes. Culture moderates this effect, and we discuss how perceptual strategies for ascribing expression to familiar and unfamiliar images may account for the differences.

Adolescent↗
PubMed2003

Transmission of pseudorabies virus from immune-masked blood monocytes to endothelial cells.

Pseudorabies virus (PRV) may cause abortion, even in the presence of vaccination-induced immunity. Blood monocytes are essential to transport the virus in these immune animals, including transport to the pregnant uterus. Infected monocytes express viral proteins on their cell surface. Specific antibodies recognize these proteins and should activate antibody-dependent cell lysis. Previous work showed that addition of PRV-specific polyclonal antibodies to PRV-infected monocytes induced internalization of viral cell surface proteins, protecting the cells from efficient antibody-dependent lysis in vitro (immune-masked monocytes). As a first step to reach the pregnant uterus, PRV has to cross the endothelial cell barrier of the maternal blood vessels. The current aim was to investigate in vitro whether immune-masked PRV-infected monocytes can transmit PRV in the presence of virus-neutralizing antibodies via adhesion and fusion of these monocytes with endothelial cells. Porcine blood monocytes, infected with a lacZ-carrying PRV strain, were incubated with PRV-specific antibodies to induce internalization. Then, cells were co-cultivated with endothelial cells for different periods of time. Only PRV-infected monocytes with internalized viral cell surface proteins adhered efficiently to endothelial cells. LacZ transmission to endothelial cells, as a measure for monocyte-endothelial cell fusion, could be detected after co-cultivation from 30 min onwards. Virus transmission was confirmed by the appearance of plaques. Adhesion of immune-masked PRV-infected monocytes to endothelial cells was mediated by cellular adhesion complex CD11b-CD18 and subsequent fusion was mediated by the virus. In conclusion, immune-masked PRV-infected monocytes can adhere and subsequently transmit virus to endothelial cells in the presence of PRV-neutralizing antibodies.

Animals↗
PubMed2006

Photonic band-gap formation by optical-phase-mask lithography.

We demonstrate an approach for fabricating photonic crystals with large three-dimensional photonic band gaps (PBG's) using single-exposure, single-beam, optical interference lithography based on diffraction of light through an optical phase mask. The optical phase mask (OPM) consists of two orthogonally oriented binary gratings joined by a thin, solid layer of homogeneous material. Illuminating the phase mask with a normally incident beam produces a five-beam diffraction pattern which can be used to expose a suitable photoresist and produce a photonic crystal template. Optical-phase-mask Lithography (OPML) is a major simplification from the previously considered multibeam holographic lithography of photonic crystals. The diffracted five-beam intensity pattern exhibits isointensity surfaces corresponding to a diamondlike (face-centered-cubic) structure, with high intensity contrast. When the isointensity surfaces in the interference patterns define a silicon-air boundary in the resulting photonic crystal, with dielectric contrast 11.9 to 1, the optimized PBG is approximately 24% of the gap center frequency. The ideal index contrast for the OPM is in the range of 1.7-2.3. Below this range, the intensity contrast of the diffraction pattern becomes too weak. Above this range, the diffraction pattern may become too sensitive to structural imperfections of the OPM. When combined with recently demonstrated polymer-to-silicon replication methods, OPML provides a highly efficient approach, of unprecedented simplicity, for the mass production of large-scale three-dimensional photonic band-gap materials.

Journal Article↗
PubMed2004

Perceptually-weighted evaluation criteria for segmentation masks in video sequences.

In order to complement subjective evaluation of the quality of segmentation masks, this paper introduces a procedure for automatically assessing this quality. Algorithmically computed figures of merit are proposed. Assuming the existence of a perfect reference mask (ground truth), generated manually or with a reliable procedure over a test set, these figures of merit take into account visually desirable properties of a segmentation mask in order to provide the user with metrics that best quantify the spatial and temporal accuracy of the segmentation masks. For the sake of easy interpretation, results are presented on a peaked signal-to-noise ratio-like logarithmic scale.

Algorithms↗
PubMed1989

Clinical masking with tragal rubbing and the Bárány noise-box.

When assessing hearing by free-field voice testing, it is essential to mask the non-test ear. An appropriate method of masking must be chosen to suit the stimulus used. This study demonstrates that tragal rubbing is an effective means of masking a whispered or conversational voice, but a Bárány noise-box is required to mask a loud voice. However, a Bárány noise-box should not be used routinely as it is likely to overmask a normal or mildly impaired ear.

Adult↗
PubMed1994

Conscious and nonconscious processes: an ERP index of an anticipatory response in a conditioning paradigm using visually masked stimuli.

This study investigates the nonconscious elicitation of a previously conditioned response by using a differential conditioning paradigm with visually masked affectively valent facial schematics. Electrodermal (skin conductance response [SCR] and brain (event-related potential [ERP]) activity were main dependent measures. Following a preconditioning phase in which subjects viewed energy masked pleasant and unpleasant facial schematics, conditioning with an aversive shock was established to unmasked presentations of an unpleasant face in a partial factorial design. A postconditioning phase of masked presentations, when compared with the preconditioning phase, revealed how the conditional effect within awareness might affect the same stimuli when presented outside awareness. An adaptive staircase technique was used to establish individual threshold levels, which represented a methodological advance over procedures typically used in visual masking research. The results revealed that responses to the CS+ (unpleasant face) changed significantly in predicted directions from preconditioning to postconditioning phase when compared with responses to the CS- (pleasant face). The SCR results systematically replicated recent Ohman, Dimberg, and Esteves (1988) findings, with the pattern of responses resembling a resistance to extinction effect. A new finding emerged for the brain responses. For the CS+, distinct slow wave activity occurred just before the point at which the shock had been delivered in the conditioning phase; no such activity was found for the CS-. This slow wave activity is similar to what has been described by others as an expectancy wave. The results indicate that an anticipatory process, as indexed by different physiological systems, can be elicited entirely outside awareness. Implications are discussed in regard to the nature of conscious and nonconscious processes.

Adult↗
PubMed2004

Removal of bone in CT angiography of the cervical arteries by piecewise matched mask bone elimination.

In maximum intensity projection (MIP) images of CT angiography (CTA) scans, the arteries are often obscured by bone. A bone removal method is presented that uses an additional, nonenhanced scan to create a mask of the bone by thresholding and dilation. After registration of the CTA scan and the additional scan, the bone in the CTA scan is masked. As the cervical area contains bones that can move with respect to each other, these bones are separated first using a watershed algorithm, and then registered individually. A phantom study was performed to evaluate and quantify the tradeoff between the removal of the bone and the preservation of the arteries contiguous to the bone. The influence of algorithm parameters and scan parameters was studied. The method was clinically evaluated with data sets of 35 patients. Best results were obtained with a threshold of 150 HU and a dilation of 8 in-plane voxels and two out-of-plane voxels. The mean width of the soft tissue layer, which is also masked, was approximately 1 mm. The mAs value of the nonenhanced scan could be reduced from 250 mAs to 65 mAs without a loss of quality. In 32 cases the bones were registered correctly and removed completely. In three cases the bone separation was not completely successful, and consequently the bone was not completely removed. The piecewise matched mask bone elimination method proved to be able to obtain MIP images of the cervical arteries free from overprojecting bone in a fully automatic way and with only a slight increase of radiation dose.

Algorithms↗
PubMed1985

Simultaneous masking by gated and continuous sinusoidal maskers.

Simultaneous masking of a 20-ms, 1-kHz signal was investigated using 50-ms gated and continuous sinusoidal maskers with frequencies below, at, and above 1 kHz. Gated maskers can produce considerably (5-20 dB) more masking than continuous maskers, and this difference does not appear to result from the spread of energy produced by gating either the masker or the signal. For masker frequencies below the signal frequency, this difference in masking is primarily due to the detection of the cubic difference tone in the continuous condition. For masker frequencies at and above the signal frequency, the difference appears to be an important property of masking. Implications of this frequency-dependent effect for measures of frequency selectivity are discussed.

Acoustic Stimulation↗
PubMed1987

Gap detection and masking in hearing-impaired and normal-hearing subjects.

Subjects with cochlear impairments often show reduced temporal resolution as measured in gap-detection tasks. The primary goals of these experiments were: to assess the extent to which the enlarged gap thresholds can be explained by elevations in absolute threshold; and to determine whether the large gap thresholds can be explained by the same processes that lead to a slower-than-normal recovery from forward masking. In experiment I gap thresholds were measured for nine unilaterally and eight bilaterally impaired subjects, using bandlimited noise stimuli centered at 0.5, 1.0, and 2.0 kHz. Gap thresholds were usually larger for the impaired ears, even when the comparisons were made at equal sensation levels (SLs). Gap thresholds tended to increase with increasing absolute threshold, but the scatter of gap thresholds was large for a given degree of hearing loss. In experiment II threshold was measured as a function of the delay between the onset of a 210-ms masker and the onset of a 10-ms signal in both simultaneous- and forward-masking conditions. The signal frequency was equal to the center frequency of the bandlimited noise masker, which was 0.5, 1.0, or 2.0 kHz. Five subjects with unilateral cochlear impairments, two subjects with bilateral impairments, and two normal subjects were tested. The rate of recovery from forward masking, particularly the initial rate, was usually slower for the impaired ears, even when the maskers were presented at equal SLs. Large gap thresholds tended to be associated with slow rates of recovery from forward masking.

Acoustic Stimulation↗
PubMed1987

Vowel identification and vowel masking patterns of hearing-impaired subjects.

Confusion matrices for seven synthetic steady-state vowels were obtained from ten normal and three hearing-impaired subjects. The vowels were identified at greater than 96% accuracy by the normals, and less accurately by the impaired subjects. Shortened versions of selected vowels then were used as maskers, and vowel masking patterns (VMPs) consisting of forward-masked threshold for sinusoidal probes at all vowel masker harmonics were obtained from the impaired subjects and from one normal subject. Vowel-masked probe thresholds were transformed using growth-of-masking functions obtained with flat-spectrum noise. VMPs of the impaired subjects, relative to those of the normal, were characterized by smaller dynamic range, poorer peak resolution, and poorer preservation of the vowel formant structure. These VMP characteristics, however, did not necessarily coincide with inaccurate vowel recognition. Vowel identification appeared to be related primarily to VMP peak frequencies rather than to the levels at the peaks or to between-peak characteristics of the patterns.

Acoustic Stimulation↗
PubMed1970

Presence of binding site for alpha-amylase and of masking protein for this site on mycelial cell wall of Aspergillus oryzae.

Mycelial cell wall of Aspergillus oryzae M-13 grown in an alpha-amylase-forming medium could not bind alpha-amylase (Taka-amylase A, EC 3.2.1.1). However, by treatment with 1.0 n NaOH at 100 C for 30 min, the wall gained the ability to bind alpha-amylase. This phenomenon was caused by removal of a factor (designated as masking factor) which masked the binding site for alpha-amylase. The masking factor was purified as a preparation giving a single peak in both ultracentrifugation (1.6S) and by gel electrophoresis (M(BPB), 1.0). Approximately 20 mug of the purified factor, bound to 10 mg of the alkali-treated mycelial cell wall, prevented the binding of approximately 100 mug of alpha-amylase or released approximately 100 mug of alpha-amylase which previously was bound to the alkali-treated wall. These findings indicate that the factor has much higher affinity than alpha-amylase for the binding site on the mycelial wall. The masking factor was inducibly formed accompanying the secretion of alpha-amylase.

Amylases↗
PubMed1983

Light-dark masking of circadian temperature and activity rhythms in squirrel monkeys.

In addition to the synchronizing effects of light-dark cycles on the circadian timing system, light per se can have a direct masking effect on the rhythmic variables monitored as indicators of the circadian system. To evaluate the masking action of light on the rest-activity and body temperature rhythms of squirrel monkeys (Saimiri sciureus), animals were exposed to cycles of 2 h of light alternating with 2 h of darkness (LD 2:2). There was evidence of phase-dependent masking responses in both rhythms, with the light-induced elevation of activity levels and temperature greatest around the times of the circadian maxima of the respective rhythms. The temporal distribution of activity was more strongly affected by the masking action of the 2:2 cycle than was the temporal pattern of temperature variation. The increase in activity observed during lights on was evidently a major factor contributing to the corresponding increase in temperature.

Animals↗
PubMed1982

Masked depression--an ambiguous entity.

The term 'masked depression' is not accepted in current psychiatric classification for three basic reasons: (1) It is not a unique type of a disease or a syndrome, but a state or a stage which is a part of the depressive syndromes. (2) No special list of symptoms which has enough specificity, reliability and validity can be drawn in order to describe this state. (3) The term 'masked' is vague, and is in contradiction to the basic necessity to describe what is observed in contrast to what is unobservable and masked. However, precise and scientific criteria may be unsuitable for diagnostic purposes in these cases which are quite common; thus an entity which has a deep meaning and begs recognition among general physicians may be ignored. In addition, diagnosis of such depression is very important to allow for suitable and adequate treatment procedures. Diagnostic problems, clarification of the term 'masked' and the procedures of diagnosis are discussed in the article.

Depressive Disorder↗
PubMed1983

Effects of a face mask and pneumotachograph on breathing in sleeping infants.

The effect of facial attachments on breathing was measured by respiratory induction plethysmography (RIP) during quiet sleep in 32 studies in 18 infants. The addition of a face mask plus pneumotachograph led to an increase in tidal volume (VT) (22.0 +/- 13.5%, p less than 0.01) during 5-min sleep studies when compared to measurements using RIP alone. Applying only the mask rim also led to an increase in VT (14.6 +/- 3.1%, p less than 0.05). A significant increase in VT was noted in 3 of 6 infants studied when a lightweight cardboard ring was in place perinasally. Respiratory frequency fell significantly in the mask/pneumotachograph group (-5.9 +/- 10.0%, p less than 0.05) and with the mask rim (-7.4 +/- 8.8%, p less than 0.01), but there was individual infant variation. Minute ventilation rose significantly (19.1 +/- 16.9%, p less than 0.01) only with the addition of the mask and pneumotachograph. Instrument deadspace can account for some of the increase in VT noted, but in its absence, sensory stimulation of the trigeminal area can augment tidal breathing.

Humans↗
PubMedDate not supplied

Indirect calorimetry: comparison of hood and mask systems for measuring resting energy expenditure in healthy volunteers.

Controversy exists as to the validity and reliability of hood and mask systems in measuring indirect calorimetry. The purpose of this study was to evaluate the accuracy and reproducibility of repeat measurements of resting energy expenditure (REE) in volunteers. Paired REE measurements were performed in 23 subjects after an overnight fast using hood and mask systems. Lean body mass was calculated from four skinfold measurements and body weight determinations. Data were normalized to body weight and lean body mass and were calculated as percent predicted REE in paired tests taken within 5 minutes on the same subject. No significant difference in mean REE was noted between hood and mask systems. Linear regression analysis showed a strong positive correlation (r = 0.91, p less than 0.001) between hood and mask measurements of REE.

Adult↗