Thermophysical properties of liquid Zr52.5Cu17.9Ni14.6Al10Ti5-prospects for bulk metallic glass manufacturing in space.

Bulk metallic glasses are of critical interest for a wide range of applications, including their use in spacecraft gearboxes and mechanisms due to their excellent low-temperature, unlubricated wear resistance. Also of interest, is the potential for in-space manufacturing of metal alloys and the use of microgravity to determine fundamental thermophysical properties to inform ground-based modeling and experimentation. In this work, a Zr-based bulk metallic glass was processed in the electromagnetic levitator ISS-EML to determine undercooling, electrical resistivity, specific heat capacity, surface tension, and viscosity. A 6.5 mm sphere was vitrified during the processing, resulting in the first bulk metallic glass manufactured on board the international space station (ISS).

Unconventional Magnetization below 25 K in Nitrogen-doped Diamond provides hints for the existence of Superconductivity and Superparamagnetism.

The magnetization of nitrogen-doped single crystalline diamond bulk samples shows unconventional field and temperature hysteresis loops at T [Formula: see text] 25 K. The results suggest the existence of superparamagnetic and superconducting regions in samples with nitrogen concentration <200 ppm. Both phases vanish at temperatures above 25 K where the samples show diamagnetic behavior similar to undoped diamond. The observation of superparamagnetism and superconductivity is attributed to the nitrogen doping and to the existence of defective regions. From particle-induced X-ray emission with ppm resolution we rule out that the main observations below 25 K are due to magnetic impurities. We investigated also the magnetic properties of ferromagnetic/high-temperature superconducting oxide bilayers. The magnetization results obtained from those bilayers show remarkable similarities to the ones in nitrogen-doped diamond.

Foot use during vertical climbing in chimpanzees (Pan troglodytes).

Upright bipedalism is a hallmark of hominin locomotion, however debates continue regarding the extent of arboreal locomotion and the nature of bipedalism practiced by early hominins. Pedal form and function play a prominent role in these debates, as the foot is the element that directly interacts with the locomotor substrate. Recent finds have substantially increased the availability of associated foot remains of early hominins and emphasized the enigmatic nature of the early evolution of human bipedalism. New discoveries of associated forefoot remains have afforded the opportunity to assess relative proportions across the forefoot of fossil hominins and illuminated the need for data on relative loading across the forefoot in extant hominoids. In order to provide functional data with which to examine the relationship between bony features and load distribution across the forefoot during climbing, we present the first analysis of plantar pressure distribution across the forefoot of chimpanzees climbing a vertical support. Chimpanzees load the medial metatarsals and first toe disproportionately during vertical climbing. Peak pressures on these elements occur at the end of stance phase during climbing and are higher than on any other elements of the foot. Toe pressures are considerably higher during vertical climbing than during knuckle-walking or movement on horizontal poles, supporting the notion that the plantarly-broad and dorsally-narrow metatarsal heads in chimpanzees and some early hominins are associated with close-packing of the metatarsophalangeal joint during climbing.

Dissecting Driver Behaviors Under Cognitive, Emotional, Sensorimotor, and Mixed Stressors.

In a simulation experiment we studied the effects of cognitive, emotional, sensorimotor, and mixed stressors on driver arousal and performance with respect to (wrt) baseline. In a sample of n = 59 drivers, balanced in terms of age and gender, we found that all stressors incurred significant increases in mean sympathetic arousal accompanied by significant increases in mean absolute steering. The latter, translated to significantly larger range of lane departures only in the case of sensorimotor and mixed stressors, indicating more dangerous driving wrt baseline. In the case of cognitive or emotional stressors, often a smaller range of lane departures was observed, indicating safer driving wrt baseline. This paradox suggests an effective coping mechanism at work, which compensates erroneous reactions precipitated by cognitive or emotional conflict. This mechanisms' grip slips, however, when the feedback loop is intermittently severed by sensorimotor distractions. Interestingly, mixed stressors did not affect crash rates in startling events, suggesting that the coping mechanism's compensation time scale is above the range of neurophysiological latency.

Active charge state control of single NV centres in diamond by in-plane Al-Schottky junctions.

In this paper, we demonstrate an active control of the charge state of a single nitrogen-vacancy (NV) centre by using in-plane Schottky-diode geometries with aluminium on hydrogen-terminated diamond surface. A switching between NV(+), NV(0) and NV(-) can be performed with the Al-gates which apply electric fields in the hole depletion region of the Schottky junction that induces a band bending modulation, thereby shifting the Fermi-level over NV charge transition levels. We simulated the in-plane band structure of the Schottky junction with the Software ATLAS by solving the drift-diffusion model and the Poisson-equation self-consistently. We simulated the IV-characteristics, calculated the width of the hole depletion region, the position of the Fermi-level intersection with the NV charge transition levels for different reverse bias voltages applied on the Al-gate. We can show that the field-induced band bending modulation in the depletion region causes a shifting of the Fermi-level over NV charge transition levels in such a way that the charge state of a single NV centre and thus its electrical and optical properties is tuned. In addition, the NV centre should be approx. 1-2 µm away from the Al-edge in order to be switched with moderate bias voltages.

Modulation of radiochemoimmunotherapy-induced B16 melanoma cell death by the pan-caspase inhibitor zVAD-fmk induces anti-tumor immunity in a HMGB1-, nucleotide- and T-cell-dependent manner.

One prerequisite that radiotherapy (RT) and chemotherapy (CT) result in anti-tumor immune responses is triggering of immunogenic cell death forms such as necroptosis. The latter is inducible by inhibition of apoptosis with the pan-caspase inhibitor zVAD-fmk. The design of multimodal therapies that overcome melanoma's resistance to apoptosis is a big challenge of oncoimmunology. As hints exist that immune stimulation by hyperthermia (HT) augments the efficacy of melanoma therapies and that tumors can be sensitized for RT with zVAD-fmk, we asked whether combinations of RT with dacarbazine (DTIC) and/or HT induce immunogenic melanoma cell death and how this is especially influenced by zVAD-fmk. Necroptosis was inducible in poorly immunogenic B16-F10 melanoma cells and zVAD-fmk generally increased melanoma cell necrosis concomitantly with the release of HMGB1. Supernatants (SNs) of melanoma cells whose cell death was modulated with zVAD-fmk induced an upregulation of the activation markers CD86 and MHCII on macrophages. The same was seen on dendritic cells (DCs), but only when zVAD-fmk was added to multimodal tumor treatments including DTIC. DCs of MyD88 KO mice and DCs incubated with SNs containing apyrase did not increase the expression of these activation markers on their surface. The in vivo experiments revealed that zVAD-fmk decreases the tumor growth significantly and results in a significantly reduced tumor infiltration of Tregs when added to multimodal treatment of the tumor with RT, DTIC and HT. Further, a significantly increased DC and CD8+ T-cell infiltration into the tumor and in the draining lymph nodes was induced, as well as an increased expression of IFNγ by CD8+ T cells. However, zVAD-fmk did not further reduce tumor growth in MyD88 KO mice, mice treated with apyrase or RAG KO mice. We conclude that HMGB1, nucleotides and CD8+ T cells mediate zVAD-fmk induced anti-melanoma immune reactions in multimodal therapy settings.

Inhibition-induced plasticity in tinnitus patients after repetitive exposure to tailor-made notched music.

OBJECTIVE: Notch-filtered music has been shown to induce frequency-specific inhibition. Here, we investigated which cortical structures are affected by tailor-made notched music (TMNM) in tinnitus patients and how this inhibition-induced plasticity develops over time. METHODS: Nine subjects suffering from chronic tonal tinnitus listened to music passing through a notch-filter centered at the patient's individual tinnitus frequency (TMNM) for three hours on three consecutive days. Before and after each listening session, a tone at the tinnitus frequency and a control tone of 500 Hz were presented in the magnetoencephalograph. Subjective tinnitus loudness was measured via visual analog scales. RESULTS: TMNM exposure reduced subjective tinnitus loudness and neural activity evoked by the tinnitus tone in temporal, parietal and frontal regions within the N1m time interval. Reduction of temporal and frontal activation correlated significantly with tinnitus loudness decline. Reduction of tinnitus related neural activity persisted and accumulated over three days. CONCLUSIONS: Inhibition-induced plasticity occurs in a cortical network, known to be crucial for tinnitus perception. This cortical reorganization evolves fast and accumulates across sessions. SIGNIFICANCE: This study extends previous work on inhibition-induced plasticity, as it demonstrates the involvement of parietal and frontal areas and discovers a cumulative effect of cortical reorganization in tinnitus patients.

Low and moderate doses of ionizing radiation up to 2 Gy modulate transmigration and chemotaxis of activated macrophages, provoke an anti-inflammatory cytokine milieu, but do not impact upon viability and phagocytic function.

Benign painful and inflammatory diseases have been treated for decades with low/moderate doses of ionizing radiation (LD-X-irradiation). Tissue macrophages regulate initiation and resolution of inflammation by the secretion of cytokines and by acting as professional phagocytes. Having these pivotal functions, we were interested in how activated macrophages are modulated by LD-X-irradiation, also with regard to radiation protection issues and carcinogenesis. We set up an ex-vivo model in which lipopolysaccharide pre-activated peritoneal macrophages (pMΦ) of radiosensitive BALB/c mice, mimicking activated macrophages under inflammatory conditions, were exposed to X-irradiation from 0·01 Gy up to 2 Gy. Afterwards, the viability of the pMΦ, their transmigration and chemotaxis, the phagocytic behaviour, the secretion of inflammatory cytokines and underlying signalling pathways were determined. Exposure of pMΦ up to a single dose of 2 Gy did not influence their viability and phagocytic function, an important fact regarding radiation protection. However, significantly reduced migration, but increased chemotaxis of pMΦ after exposure to 0·1 or 0·5 Gy, was detected. Both might relate to the resolution of inflammation. Cytokine analyses revealed that, in particular, the moderate dose of 0·5 Gy applied in low-dose radiotherapy for inflammatory diseases results in an anti-inflammatory cytokine microenvironment of pMΦ, as the secretion of the proinflammatory cytokine interleukin (IL)-1ß was reduced and that of the anti-inflammatory cytokine transforming growth factor (TGF)-ß increased. Further, the reduced secretion of IL-1ß correlated with reduced nuclear translocation of nuclear factor (NF)-κB p65, starting at exposure of pMΦ to 0·5 Gy of X-irradiation. We conclude that inflammation is modulated by LD-X-irradiation via changing the inflammatory phenotype of macrophages.

Dynamics of locomotor transitions from arboreal to terrestrial substrates in Verreaux's sifaka (Propithecus verreauxi).

Most primates are able to move with equal facility on the ground and in trees, but most use the same quadrupedal gaits in both environments. A few specialized primates, however, use a suspensory or leaping mode of locomotion when in the trees but a bipedal gait while on the ground. This is a rare behavioral pattern among mammals, and the extent to which the bipedal gaits of these primates converge and are constrained by the anatomical and neurological adaptations associated with arboreal locomotion is poorly understood. Sifakas (Propithecus), primates living only in Madagascar, are highly committed vertical clingers and leapers that also spend a substantial amount of time on the ground. When moving terrestrially sifakas use a unique bipedal galloping gait seen in no other mammals. Little research has examined the mechanics of these gaits, and most of that research has been restricted to controlled captive conditions. The energetic costs associated with leaping and bipedal galloping are unknown. This study begins to fill that gap using triaxial accelerometry to characterize and compare the dynamics of sifakas' leaping and bipedal galloping behavior. As this is a relatively novel approach, the first goal of this article is to explore the feasibility of collecting such data on free-roaming animals and attempt to automate the identification of leaping and bipedal behavior within the output. The second goal is to compare the overall accelerations of the body and to use that as an approximation of aspects of energetic costs during leaping and bipedalism. To achieve this, a lightweight accelerometer was mounted on freely moving sifakas. The resulting acceleration profiles were processed, and sequences of leaps (bouts) were automatically extracted from the waveforms with 85% accuracy. Both vector dynamic body acceleration and overall dynamic body acceleration (ODBA) were used to characterize locomotor patterns and energy expenditure during leaping and bipedalism. The unique kinematics of the gait of sifakas, and the mechanics of bouts involving a string of successive leaps or gallops, appear to minimize redirections of the center of mass as well as the number of acceleration peaks and ODBAs. These results suggest that bipedal galloping is not only a reflection of the unique anatomical configuration of a leaping primate, but it may also provide a musculoskeletal and an energetic advantage to sifakas. In that sense, bipedal galloping represents an advantageous way for sifakas to move when transitioning from arboreal leaping to terrestrial locomotion.

A learning-enabled neuron array IC based upon transistor channel models of biological phenomena.

We present a single-chip array of 100 biologically-based electronic neuron models interconnected to each other and the outside environment through 30,000 synapses. The chip was fabricated in a standard 350 nm CMOS IC process. Our approach used dense circuit models of synaptic behavior, including biological computation and learning, as well as transistor channel models. We use Address-Event Representation (AER) spike communication for inputs and outputs to this IC. We present the IC architecture and infrastructure, including IC chip, configuration tools, and testing platform. We present measurement of small network of neurons, measurement of STDP neuron dynamics, and measurement from a compiled spiking neuron WTA topology, all compiled into this IC.

Induction of abscopal anti-tumor immunity and immunogenic tumor cell death by ionizing irradiation - implications for cancer therapies.

Although cancer progression is primarily driven by the expansion of tumor cells, the tumor microenvironment and anti-tumor immunity also play important roles. Herein, we consider how tumors can become established by escaping immune surveillance and also how cancer cells can be rendered visible to the immune system by standard therapies such as radiotherapy or chemotherapy, either alone or in combination with additional immune stimulators. Although local radiotherapy results in DNA damage (targeted effects), it is also capable of inducing immunogenic forms of tumor cell death which are associated with a release of immune activating danger signals (non-targeted effects), such as necrosis. Necrotic tumor cells may result from continued exposure to death stimuli and/or an impaired phosphatidylserine (PS) dependent clearance of the dying tumor cells. In such circumstances, mature dendritic cells take up tumor antigen and mediate the induction of adaptive and innate anti-tumor immunity. Locally-triggered, systemic immune activation can also lead to a spontaneous regression of tumors or metastases that are outside the radiation field - an effect which is termed abscopal. Preclinical studies have demonstrated that combining radiotherapy with immune stimulation can induce anti-tumor immunity. Given that it takes time for immunity to develop following exposure to immunogenic tumor cells, we propose practical combination therapies that should be considered as a basis for future research and clinical practice. It is essential that radiation oncologists become more aware of the importance of the immune system to the success of cancer therapy.

The foot of Homo floresiensis.

Homo floresiensis is an endemic hominin species that occupied Liang Bua, a limestone cave on Flores in eastern Indonesia, during the Late Pleistocene epoch. The skeleton of the type specimen (LB1) of H. floresiensis includes a relatively complete left foot and parts of the right foot. These feet provide insights into the evolution of bipedalism and, together with the rest of the skeleton, have implications for hominin dispersal events into Asia. Here we show that LB1's foot is exceptionally long relative to the femur and tibia, proportions never before documented in hominins but seen in some African apes. Although the metatarsal robusticity sequence is human-like and the hallux is fully adducted, other intrinsic proportions and pedal features are more ape-like. The postcranial anatomy of H. floresiensis is that of a biped, but the unique lower-limb proportions and surprising combination of derived and primitive pedal morphologies suggest kinematic and biomechanical differences from modern human gait. Therefore, LB1 offers the most complete glimpse of a bipedal hominin foot that lacks the full suite of derived features characteristic of modern humans and whose mosaic design may be primitive for the genus Homo. These new findings raise the possibility that the ancestor of H. floresiensis was not Homo erectus but instead some other, more primitive, hominin whose dispersal into southeast Asia is still undocumented.

Manual digital pressures during knuckle-walking in chimpanzees (Pan troglodytes).

Considerable attention has been given to hand morphology and function associated with knuckle-walking in the African apes because of the implications they have for the evolution of bipedalism in early hominins. Knuckle-walking is associated with a unique suite of musculoskeletal features of the wrist and hand, and numerous studies have hypothesized that these anatomical features are associated with the dynamics of load distribution across the digits during knuckle-walking. We collected dynamic digital pressures on two chimpanzees during terrestrial and simulated arboreal locomotion. Comparisons were made across substrates, limb positions, hand positions, and age categories. Peak digital pressures were similar on the pole and on the ground but were distributed differently across the digits on each substrate. In young animals, pressure was equally high on digits 2-4 on the ground but higher on digits 3 and 4 on the pole. Older animals experience higher pressures on digits 2 and 3 on the ground. Hand posture (palm-in vs. palm-back) influenced the distribution and timing of peak pressures. Age-related increases in body mass also result in higher overall pressures and increased variation across the digital row. In chimpanzees, digit 5 typically bears relatively little load regardless of hand position or substrate. These are the first quantitative data on digital pressures during knuckle-walking in hominoids, and they afford the opportunity to develop hypotheses about variation among hominoids and biomechanical models of wrist and forearm loading.

The hands and feet of Archaeolemur: metrical affinities and their functional significance.

Recent expeditions to Madagascar have recovered abundant skeletal remains of Archaeolemur, one of the so-called "monkey lemurs" known from Holocene deposits scattered across the island. These new skeletons are sufficiently complete to permit reassembly of entire hands and feet--postcranial elements crucial to drawing inferences about substrate preferences and positional behavior. Univariate and multivariate analysis of intrinsic hand and foot proportions, phalangeal indices, relative pollex and hallux lengths, phalangeal curvature, and distal phalangeal shape reveal a highly derived and unique morphology for an extinct strepsirrhine that diverges dramatically from that of living lemurs and converges in some respects on that of Old World monkeys (e.g., mandrills, but not baboons or geladas). The hands and feet of Archaeolemur are relatively short (extremely so relative to body size); the carpus and tarsus are both "long" relative to total hand and foot lengths, respectively; phalangeal indices of both the hands and feet are low; both pollex and hallux are reduced; the apical tufts of the distal phalanges are very broad; and the proximal phalanges are slightly curved (but more so than in baboons). Overall grasping capabilities may have been compromised to some extent, and dexterous handling of small objects seems improbable. Deliberate and noncursorial quadrupedalism was most likely practiced on both the ground and in the trees. A flexible locomotor repertoire in conjunction with a eurytopic trophic adaptation allowed Archaeolemur to inhabit much of Madagascar and may explain why it was one of the latest surviving subfossil lemurs.

Functional status of persons with diabetes-related lower-extremity amputations.

OBJECTIVE: It is reasonable to predict that diabetes-related lower-extremity amputations have a detrimental impact on quality of life. However, we are unaware of any study in the medical literature describing the functional level of diabetic patients with amputations. The objective of this study was to evaluate amputations among diabetic patients and to determine the functional level of these patients with the Sickness Impact Profile (SIP). RESEARCH DESIGN AND METHODS: We enrolled 124 patients with diabetes. Case subjects (n = 35) were defined as patients who had undergone amputation of the lower-extremity, and control subjects (n = 89) were defined as patients who had not undergone amputation. Study participants received a standard history and physical examination. RESULTS: Both the physical dimension scores (33.5 +/- 14.9 vs. 22.3 +/- 14.7, P < 0.001) and the total SIP scores (27.6 +/- 9.9 vs. 22.5 +/- 10.3, P = 0.013) were significantly higher for amputees. However, the psychosocial dimension scores were not significantly different between case and control subjects (14.9 +/- 8.9 vs. 15.2 +/- 10.0, P > 0.05). Post hoc analysis showed that the group of patients who had undergone transtibial amputation had a significantly higher total impairment score than patients who had not undergone amputation (P = 0.039). This is in contrast to patients with toe or midfoot amputations, for whom total impairment scores were not significantly higher than those for the control subjects. Interestingly, bilateral amputees did not have significantly higher scores on either SIP dimension compared with unilateral amputees. CONCLUSIONS: These findings exemplify the detrimental physical and psychosocial health status of patients with diabetes-related lower-extremity amputation.

Gender differences in adult foot shape: implications for shoe design.

PURPOSE: To analyze gender differences in foot shape in a large sample of young individuals. METHODS: Univariate t-tests and multivariate discriminant analyses were used to assess 1) significant differences between men and women for each foot and leg dimension, standardized to foot length, 2) the reliability of classification into gender classes using the absolute and standardized variable sets, and 3) the relative importance of each variable to the discrimination between men and women. RESULTS: Men have longer and broader feet than women for a given stature. After normalization of the measurements by foot length, men and women were found to differ significantly in two calf, five ankle, and four foot shape variables. Classification by gender using absolute values was correct at least 93% of the time. Using the variables standardized to foot length, gender was correctly classified 85% of the time. CONCLUSIONS: This study demonstrates that female feet and legs are not simply scaled-down versions of male feet but rather differ in a number of shape characteristics, particularly at the arch, the lateral side of the foot, the first toe, and the ball of the foot. These differences should be taken into account in the design and manufacture of women's sport shoes.

Systemic hyperbaric oxygen therapy: lower-extremity wound healing and the diabetic foot.

OBJECTIVE: To document peer-reviewed medical publications that have reported on hyperbaric oxygen (HBO) therapy as an adjunct to standard lower-extremity wound care, focusing on publications dealing with the diabetic foot. RESEARCH DESIGN AND METHODS: A review of the medical literature was conducted using MEDLINE. Research articles involving HBO treatment and the diabetic foot were critiqued to identify factors that may have been a source of bias. RESULTS: Of the published reports on human studies, seven involved diabetes-related foot pathology. Five of these studies, two of which were randomized, included a control group that did not receive HBO therapy The controlled diabetic foot studies included an average of 28 subjects in the HBO therapy group (range 10-62) and an average of 16.2 subjects in the non-HBO control group (range 5-33). Most of the published reports have several potential sources of bias, including, but not limited to, inadequate evaluation of comorbid conditions relevant to wound healing, small sample size, and poor documentation of wound size or severity. Four of the seven reports involving the diabetic foot were published by a group of researchers at the University of Milan between 1987 and 1996. CONCLUSIONS: Additional randomized placebo-controlled clinical trials in large diabetic populations would further lend credence to the presumption that HBO therapy improves clinical outcomes. Given the relatively high cost of this treatment modality, perhaps a more acute awareness of the medical literature would reduce the economic burden that HBO therapy imposes on care providers that are financially at risk.

Reliability of digital videometry and acetate tracing in measuring the surface area of cutaneous wounds.

PURPOSE: The purpose of this study was to evaluate the reliability of digital videometry and acetate tracing in the measurement of cutaneous wound area. METHODS: Four clinicians used both digital videometry and acetate tracing to measure five wounds that were artificially created on a cadaver specimen. In addition, the clinicians used an analog centimeter ruler to determine a rough estimate of the area of each wound. The wounds were measured a total of five times with each measurement instrument using a non-sequential repeat measures design. Associations between the three wound measurement techniques were examined with Pearson correlation coefficients. In addition, intraclass correlation coefficients (ICC) were calculated for each pair of the three measurement techniques. RESULTS: Correlation between the measurement systems for all raters combined yielded Pearson r-values of 0.93 for ruler and acetate, 0.95 for ruler and digital and 0.97 for acetate and digital. Furthermore, the average measure ICC between acetate and digital was 0.94, between acetate and ruler was 0.76 and between digital and ruler was 0.57. CONCLUSION: These results suggest that wound area measurements obtained using digital videometry and acetate tracing are very similar and both techniques can be used interchangeably in either clinical or research settings.

A survey of bedside methods used to detect pulmonary aspiration of enteral formula in intubated tube-fed patients.

BACKGROUND: The most frequently recommended methods to assess for pulmonary aspiration of enteral formula in intubated, tube-fed patients are (1) adding dye to enteral formulas and observing for dye-stained tracheal secretions and (2) testing tracheal secretions with glucose oxidase reagent strips to detect the presence of glucose-rich formula. Reportedly, the glucose method is more sensitive than the dye method, and the dye method may have greater potential for harm. It is not known if this information has resulted in wider use of the glucose method in practice settings. OBJECTIVES: To describe the frequency with which nurses in intensive care units use the dye and glucose methods to detect pulmonary aspiration of enteral formula in tube-fed, intubated patients. METHODS: One registered nurse in the medical intensive care unit at 285 acute-care facilities was contacted by telephone and asked about the methods used to detect pulmonary aspiration of enteral formula in tube-fed, intubated adult patients. RESULTS: Responses were obtained from 281 facilities. More than 73% of the respondents reported using only the dye method; about 1% reported using only the glucose method. Approximately 13% used both methods; another 13% did not use either method. CONCLUSIONS: The dye method is used far more often than is the glucose method. Two probable reasons are that the dye method is easier to implement, and it is recommended in commonly used basic nursing textbooks.

Patients' perceptions of uncertainty and stress during weaning from mechanical ventilation.

Weaning from mechanical ventilation is physiologically and psychologically stressful for patients. The critical care nurse is in an optimal position to reduce patients' stress during this process. The findings of this exploratory study suggest practice changes--based on patients' perspectives--that help reduce patients' feelings of uncertainty and stress as they are weaned from mechanical ventilation.