Fatigue in children who have recently completed treatment for acute lymphoblastic leukemia: a longitudinal study

BACKGROUND

This study examined fatigue in patients treated for childhood acute lymphoblastic leukemia (ALL) over a 2-year period (3- to 27-months post-treatment completion), from the perspective of children and parent caregivers, compared to a healthy comparison group.

METHODS

Eighty-three patients (4-16 years at enrolment) and their parents, reported on the child's fatigue using the Pediatric Quality of Life Inventory- Multidimensional Fatigue Scale (PedsQL-MFS), at 3- 15- and 27-months post-treatment completion, and 53 healthy children and their parents reported on fatigue across the same timepoints.

RESULTS

Parent proxy-reporting showed that parents of ALL patients reported more total fatigue than parents of the comparison group at all time points, with all subscales elevated (general, cognitive, and sleep/rest fatigue). In contrast, patient self-report of fatigue over this period differed from the comparison children for the general fatigue subscale only. Self-reported total fatigue was worse than the comparison group at the 27-month timepoint, with cognitive and sleep/rest fatigue symptoms contributing to this difference. Expected improvements in fatigue over time were not evident in either patient or parent report and no demographic risk factors were identified. Parents and children from both groups reported significantly more fatigue at all time points compared to commonly utilised normative population data.

CONCLUSIONS

Patients treated for childhood ALL are impacted by fatigue symptoms in the post-treatment and early survivorship period. These findings highlight that patients in the 2-years following treatment require increased symptom surveillance and may benefit particularly from interventions that target cognitive and sleep/rest fatigue.

Atmospheric molecular blobs shape up circumstellar envelopes of AGB stars

During their thermally pulsing phase, asymptotic giant branch (AGB) stars eject material that forms extended dusty envelopes1. Visible polarimetric imaging found clumpy dust clouds within two stellar radii of several oxygen-rich stars2-6. Inhomogeneous molecular gas has also been observed in multiple emission lines within several stellar radii of different oxygen-rich stars, including W Hya and Mira7-10. At the stellar surface level, infrared images have shown intricate structures around the carbon semiregular variable R Scl and in the S-type star π1 Gru11,12. Infrared images have also shown clumpy dust structures within a few stellar radii of the prototypical carbon AGB star IRC+10°216 (refs. 13,14), and studies of molecular gas distribution beyond the dust formation zone have also shown complex circumstellar structures15. Because of the lack of sufficient spatial resolution, however, the distribution of molecular gas in the stellar atmosphere and the dust formation zone of AGB carbon stars is not known, nor is how it is subsequently expelled. Here we report observations with a resolution of one stellar radius of the recently formed dust and molecular gas in the atmosphere of IRC+10°216. Lines of HCN, SiS and SiC2 appear at different radii and in different clumps, which we interpret as large convective cells in the photosphere, as seen in Betelgeuse16. The convective cells coalesce with pulsation, causing anisotropies that, together with companions17,18, shape its circumstellar envelope.

A survey of biosecurity and health management practices on Irish dairy farms engaged in contract-rearing

A survey was conducted to investigate potential differences in biosecurity and health management practices on Irish dairy farms that sent their heifers for contract-rearing (source dairy farms, SDF; n = 62) and those rearing their own heifers (control farms, CF; n = 50). Participating farmers were surveyed by postal questionnaire between September and November 2018. The overall response rate was 93%. Results show that structurally, SDF were larger, less fragmented, and more specialized than CF. Outsourcing of labor-intensive activities to external contractors was more common among SDF than CF, exposing them to potentially increased biosecurity risks associated with animal movements, use of shared equipment, and increased frequency of farm visitors. The majority of SDF sent heifers to a single-origin rearing facility (70%), with heifers most commonly arriving at the rearing unit between 2 and 4 mo (53%) and returning to the dairy farm between 18 and 21 mo of age (56%). Despite the increased biosecurity risk associated with contract-rearing, implementation of disease prevention measures was not superior on SDF compared with CF. For both farm types, there was scope for improvement to visitor biosecurity protocols, quarantine procedures, colostrum feeding practices, and hygiene of calving areas. This research provides an overview of the demographics and farm management practices implemented by dairy farmers engaged in contract-rearing of replacement heifers, and will serve to inform farmers, veterinary advisors, and policy makers.

Perceived cancer-related pain and fatigue, information needs, and fear of cancer recurrence among adult survivors of childhood cancer

OBJECTIVE

Pain and fatigue are under-researched late effects of childhood cancer and its treatment, and may be interpreted by survivors as indicating cancer recurrence. Moreover, unmet information needs for managing pain and fatigue may be related to fear of cancer recurrence. We investigated the complex relationships between perceived cancer-related pain and fatigue, unmet information needs for managing pain and fatigue, and fear of cancer recurrence.

METHODS

We surveyed 404 adult survivors of any form of childhood cancer (M = 16.82 years since treatment completion).

RESULTS

Many survivors reported perceived cancer-related pain (28.7%) and fatigue (40.3%), and anticipated future pain (19.3%) and fatigue (26.2%). These symptomologies were all related to unmet information needs for managing pain (18.8%) and fatigue (32.2%; all p's<.001). Survivors reporting unmet information needs for managing pain (B = .48, 95% CI = 0.19-0.76, p = .001) and fatigue (B = .32, 95% CI = 0.06-0.52, p = .015) reported higher fear of cancer recurrence than survivors reporting no information needs.

CONCLUSION

Survivors often have unmet information needs for managing pain and fatigue, and these unmet needs are related to fear of cancer recurrence.

PRACTICE IMPLICATIONS

Long-term follow-up clinics should assess pain and fatigue. Information provision about pain and fatigue may be an important tool to help manage fear of cancer recurrence.

Discovery of methyl silane and confirmation of silyl cyanide in IRC +10216

We report the discovery in space of methyl silane, CH3SiH3, from observations of ten rotational transitions between 80 and 350 GHz (Ju from 4 to 16) with the IRAM 30 m radio telescope. The molecule was observed in the envelope of the C-star IRC +10216. The observed profiles and our models for the expected emission of methyl silane suggest that the it is formed in the inner zones of the circumstellar envelope, 1-40 R*, with an abundance of (0.5-1) × 10-8 relative to H2. We also observed several rotational transitions of silyl cyanide (SiH3CN), confirming its presence in IRC +10216 in particular, and in space in general. Our models indicate that silyl cyanide is also formed in the inner regions of the envelope, around 20 R*, with an abundance relative to H2 of 6×10-10. The possible formation mechanisms of both species are discussed. We also searched for related chemical species but only upper limits could be obtained.

The growth of carbon chains in IRC +10216 mapped with ALMA

Linear carbon chains are common in various types of astronomical molecular sources. Possible formation mechanisms involve both bottom-up and top-down routes. We have carried out a combined observational and modeling study of the formation of carbon chains in the C-star envelope IRC +10216, where the polymerization of acetylene and hydrogen cyanide induced by ultraviolet photons can drive the formation of linear carbon chains of increasing length. We have used ALMA to map the emission of λ 3 mm rotational lines of the hydrocarbon radicals C2H, C4H, and C6H, and the CN-containing species CN, C3N, HC3N, and HC5N with an angular resolution of ~1″. The spatial distribution of all these species is a hollow, 5-10″ wide, spherical shell located at a radius of 10-20″ from the star, with no appreciable emission close to the star. Our observations resolve the broad shell of carbon chains into thinner sub-shells which are 1-2″ wide and not fully concentric, indicating that the mass loss process has been discontinuous and not fully isotropic. The radial distributions of the species mapped reveal subtle differences: while the hydrocarbon radicals have very similar radial distributions, the CN-containing species show more diverse distributions, with HC3N appearing earlier in the expansion and the radical CN extending later than the rest of the species. The observed morphology can be rationalized by a chemical model in which the growth of polyynes is mainly produced by rapid gas-phase chemical reactions of C2H and C4H radicals with unsaturated hydrocarbons, while cyanopolyynes are mainly formed from polyynes in gas-phase reactions with CN and C3N radicals.

Infancy and pediatric cancer: an exploratory study of parent psychological distress

BACKGROUND

Research on the psychological experiences of parents of infants within pediatric oncology is sparse. This study examined rates and indicative risk factors for psychological distress in parents where there is either an infant patient or infant sibling of a patient.

METHODS

Participants were mothers (n = 41) and fathers (n = 25) of infants under 2 years who either had a cancer diagnosis (n = 37; infant patients) or was an infant sibling of an older child with cancer (n = 29; infant siblings) recruited from a single oncology center. There were 21 couple dyads. Parents completed the Depression Anxiety Stress Scales short form and the Posttraumatic Stress Disorder Checklist.

RESULTS

Mothers (47.5%) and fathers (37.5%) reported elevated, cancer-related posttraumatic stress symptoms. Rates of depression (12.2% of mothers and 12.0% of fathers) and anxiety symptoms (17.1% of mothers and 8.0% of fathers) were lower. Compared with parents of infant patients, parents of infant siblings reported significantly higher rates of depressive symptoms and trends toward higher rates of posttraumatic stress symptoms and anxiety symptoms. Parent anxiety was higher with increased time post diagnosis. No demographic or illness-related variables were associated with psychological distress, with the exception of the number of children in the family.

CONCLUSIONS

Parent-child relationships are of fundamental importance during infancy. This study provides novel data highlighting the psychological impact for parents when a cancer diagnosis is made during this critical developmental period, including the contribution of family structure to parental distress. Results provide further support for applying a traumatic stress framework when exploring parent experiences of pediatric cancer. Copyright © 2016 John Wiley & Sons, Ltd.

Parent perceptions of managing child behavioural side-effects of cancer treatment: a qualitative study

BACKGROUND

Very little research has examined the role of parenting in managing behavioural side-effects of cancer treatment. The purpose of this paper was to explore parent perceptions of (a) parenting in the context of childhood cancer; (b) the parenting strategies used in the context of managing child behavioural side-effects of cancer treatment; and (c) the perceived impact that cancer-specific parenting strategies have on child behaviour.

METHODS

Participants were 15 mothers of children aged 2-6 years in the maintenance phase of treatment for acute lymphoblastic leukaemia at the Royal Children's Hospital Children's Cancer Centre, Melbourne, Australia. Mothers participated in a one-on-one semi-structured telephone interview using an interview guide which included questions on parenting in the context of childhood cancer, specifically in relation to behavioural side-effects (problems with behaviour, sleep and eating) and any perceived impact cancer-specific parenting may have on the ill child.

RESULTS

Many parents reported that following their child's cancer diagnosis, they had to implement a suite of 'new' strategies that 'pre-diagnosis' were used only in moderation, if at all. The most salient theme that emerged was parents' perception that their parenting became more lax since their child's diagnosis. Parents further reported specific parenting strategies for each of the main child behavioural side-effects of cancer treatment.

CONCLUSION

Data from the current qualitative exploratory study highlight the role of specific parenting strategies in managing or assisting child behavioural side-effects of cancer treatment. Further quantitative research is needed to more fully examine the association between parenting and child behavioural outcomes in order to develop modifiable approaches to improving child behavioural side-effects in a paediatric oncology context.

Discovery of SiCSi in IRC +10216: A missing link between gas and dust carriers of Si-C bonds

We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350 GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CW Leo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emission arises from a region of 6″ in radius. The derived abundance is comparable to that of SiC2. As expected from chemical equilibrium calculations, SiCSi and SiC2 are the most abundant species harboring a Si-C bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.

Work-related stress and reward: an Australian study of multidisciplinary pediatric oncology healthcare providers

OBJECTIVE

Managing staff stress and preventing long-term burnout in oncology staff are highly important for both staff and patient well-being. Research addressing work-related stress in adult oncology is well documented; however, less is known about this topic in the pediatric context. This study examined sources of work-related stress and reward specific to multidisciplinary staff working in pediatric oncology in Australia.

METHOD

Participants were 107 pediatric oncology clinicians, including medical, nursing, and allied health staff from two Australian pediatric oncology centers. Participants completed an online survey using two newly developed measures: the work stressors scale-pediatric oncology and the work rewards scale-pediatric oncology.

RESULTS

The most commonly reported sources of both stress and reward are related to patient care and interactions with children. Results indicated that levels of work-related stress and reward were similar between the professional disciplines and between the two hospitals. Regression analyses revealed no demographic or organizational factors that were associated with either stress or reward.

CONCLUSIONS

Work-related stress and reward are not mutually exclusive; particular situations and events can be simultaneously stressful and rewarding for healthcare providers. Although patient care and interactions with children was found to be the most stressful aspect of working in this speciality, it was also the greatest source of reward. Results are discussed in relation to workplace approaches to staff well-being and stress reduction.

Early psychological reactions in parents of children with a life threatening illness within a pediatric hospital setting

RESEARCH IN CONTEXT

Parents of children with life threatening illness or injuries are at elevated risk of distress reactions, involving symptoms of acute stress disorder, depression and anxiety. Currently, the impact of child illness factors is unclear, and to date research systematically examining the prevalence of these psychological reactions across different illness groups with an acute life threat is sparse. This is important to explore given that studies show that parent functioning impacts on the psychological adjustment and recovery of the ill child. WHAT DOES THIS STUDY ADD?: At four weeks following a child's diagnosis of a serious illness, 49-54% of parents met DSM-IV criteria for acute stress disorder, across a number of illness groups, whereas 15-27% of parents were in the moderate/severe range for depression and anxiety, and 25-31% for stress. Results from this study demonstrate that rates and severity of these psychological reactions in parents of seriously ill children do not vary according to illness type.

BACKGROUND

A life threatening childhood illness/injury can lead to significant distress reactions in parents, with independent studies finding such reactions in several different illness groups. To date, there is limited research systematically comparing the prevalence of adverse parental psychological reactions across different childhood illness groups with an acute life threat. This study aimed to investigate the frequency and severity of symptoms of acute traumatic stress, depression, anxiety and general stress in parents, following admission of their child to hospital for a life threatening illness. The study also aimed to explore the relationship between these symptoms, and to determine whether they differ according to illness/injury.

METHODS

Cross-sectional data from a prospective, longitudinal study are reported. Participants were 194 parents of 145 children (49 couples), admitted to cardiology (n=53), oncology (n=40) and pediatric intensive care units (n=52), for serious illnesses/injuries. Parents completed self-report questionnaires within four weeks of hospital admission.

RESULTS

Rates of acute traumatic stress (P=0.262), depression (P=0.525), anxiety (P=0.453) and general stress symptoms (P=0.720) in parents were comparable across illness type, with 49-54% reaching criteria for acute stress disorder, 15-27% having clinical levels of depression and anxiety, and 25-31% for general stress. Anxiety was most strongly associated with acute traumatic stress (r=0.56), closely followed by stress (r=0.52) and depression (r=0.49), with all correlations highly significant (P<0.001).

CONCLUSIONS

These findings provide evidence that the child's medical condition is not associated with parents' experience of clinically significant psychological symptoms, and emphasize the importance for health care providers to be aware of these potential psychological reactions in parents, regardless of the type of illness.

Optical spectra of the silicon-terminated carbon chain radicals SiCnH (n = 3,4,5)

The gas-phase optical spectra of three silicon-terminated carbon chain radicals, SiCnH (n = 3 - 5), formed in a jet-cooled discharge of silane and acetylene, have been investigated by resonant two-color two-photon ionization and laser-induced fluorescence/dispersed fluorescence. Analysis of the spectra was facilitated by calculations performed using equation-of-motion coupled cluster methods. For SiC3H and SiC5H, the observed transitions are well-described as excitations from a (2)Π ground state to a (2)Σ state, in which vibronic coupling, likely involving a higher-lying Π state with a very large predicted f-value (close to unity), is persistent. The lowest (2)Σ states of both species are characterized by a rare silicon triple bond, which was identified previously [T. C. Smith, H. Y. Li, D. J. Clouthier, C. T. Kingston, and A. J. Merer, J. Chem. Phys. 112, 3662 (2000)] in the lowest (2)Σ state of SiCH. Although a strong Π - Π transition is predicted for SiC4H, the observed spectrum near 505 nm more likely corresponds to excitation to a relatively dark Σ state which is vibronically coupled to a nearby Π state. In contrast to the chains with an odd number of carbon atoms, which exhibit relatively sharp spectral features and lifetimes in the 10-100 ns range, SiC4H shows intrinsically broadened spectral features consistent with a ∼100 fs lifetime, and a subsequent long-lived decay (>50 μs) which we ascribe to mixing with a nearby quartet state arising from the same electronic configuration. The spin-orbit coupling constants for both SiC3H and SiC5H radicals were determined to be approximately 64 cm(-1), similar to that of SiCH (69.8 cm(-1)), suggesting that the unpaired electron in these species is localized on the silicon atom. Motivated by the new optical work, the rotational spectrum of linear SiC3H was detected by cavity Fourier-transform microwave spectroscopy in the 13-34 GHz range. Each rotational transition from the [Formula: see text] ground state exhibits well-resolved Λ-doubling and hyperfine structure; the derived rotational constant of B = 2.605 GHz is in excellent agreement with our calculations.

Filtration effectiveness of HVAC systems at near-roadway schools

Concern for the exposure of children attending schools located near busy roadways to toxic, traffic-related air pollutants has raised questions regarding the environmental benefits of advanced heating, ventilation, and air-conditioning (HVAC) filtration systems for near-road pollution. Levels of black carbon and gaseous pollutants were measured at three indoor classroom sites and at seven outdoor monitoring sites at Las Vegas schools. Initial HVAC filtration systems effected a 31-66% reduction in black carbon particle concentrations inside three schools compared with ambient air concentrations. After improved filtration systems were installed, black carbon particle concentrations were reduced by 74-97% inside three classrooms relative to ambient air concentrations. Average black carbon particle concentrations inside the schools with improved filtration systems were lower than typical ambient Las Vegas concentrations by 49-96%. Gaseous pollutants were higher indoors than outdoors. The higher indoor concentrations most likely originated at least partially from indoor sources, which were not targeted as part of this intervention.

PRACTICAL IMPLICATIONS

Recent literature has demonstrated adverse health effects in subjects exposed to ambient air near major roadways. Current smart growth planning and infill development often require that buildings such as schools are built near major roadways. Improving the filtration systems of a school's HVAC system was shown to decrease children's exposure to near-roadway diesel particulate matter. However, reducing exposure to the gas-phase air toxics, which primarily originated from indoor sources, may require multiple filter passes on recirculated air.

Clinical parameters do not adequately predict outcome in necrotizing enterocolitis: a multi-institutional study

OBJECTIVE

Necrotizing enterocolitis (NEC) remains a major cause of neonatal morbidity and mortality. Some infants recover uneventfully with medical therapy whereas others develop severe disease (that is, NEC requiring surgery or resulting in death). Repeated attempts to identify clinical parameters that would reliably identify infants with NEC most likely to progress to severe disease have been unsuccessful. We hypothesized that comprehensive prospective data collection at multiple centers would allow us to develop a model which would identify those babies at risk for progressive NEC.

STUDY DESIGN

This prospective, observational study was conducted at six university children's hospitals. Study subjects were neonates with suspected or confirmed NEC. Comprehensive maternal and newborn histories were collected at the time of enrollment, and newborn clinical data were collected prospectively, thereafter. Multivariate logistic regression analysis was used to develop a predictive model of risk factors for progression.

RESULT

Of 455 neonates analyzed, 192 (42%) progressed to severe disease, and 263 (58%) advanced to full feedings without operation. The vast majority of the variables studied proved not to be associated with progression to severe disease. A total of 12 independent predictors for progression were identified, including only 3 not previously described: having a teenaged mother (odds ratio, OR, 3.14; 95% confidence interval, CI, 1.45 to 6.96), receiving cardiac compressions and/or resuscitative drugs at birth (OR, 2.51; 95% CI, 1.17 to 5.48), and having never received enteral feeding before diagnosis (OR, 2.41; 95% CI, 1.08 to 5.52).

CONCLUSION

Our hypothesis proved false. Rigorous prospective data collection of a sufficient number of patients did not allow us to create a model sufficiently predictive of progressive NEC to be clinically useful. It appears increasingly likely that further analysis of clinical parameters alone will not lead to a significant improvement in our understanding of NEC. We believe that future studies must focus on advanced biologic parameters in conjunction with clinical findings.

The rotational spectrum of CN−

The rotational spectrum of the molecular negative ion CN(-) has been detected in the laboratory at high resolution. The four lowest transitions were observed in a low pressure glow discharge through C(2)N(2) and N(2). Conclusive evidence for the identification was provided by well-resolved nitrogen quadrupole hyperfine structure in the lowest rotational transition, and a measurable Doppler shift owing to ion drift in the positive column of the discharge. Three spectroscopic constants (B, D, and eQq) reproduce the observed spectrum to within one part in 10(7) or better, allowing the entire rotational spectrum to be calculated well into the far IR to within 1 km s(-1) in equivalent radial velocity. CN(-) is an excellent candidate for astronomical detection, because the CN radical is observed in many galactic molecular sources, the electron binding energy of CN(-) is large, and calculations indicate CN(-) should be detectable in IRC+10216-the carbon star where C(6)H(-) has recently been observed. The fairly high concentration of CN(-) in the discharge implies that other molecular anions containing the nitrile group may be within reach.

Rotational spectroscopy of the isotopic species of silicon monosulfide, SiS

Pure rotational transitions of silicon monosulfide ((28)Si(32)S) and its rare isotopic species have been observed in their ground as well as vibrationally excited states by employing Fourier transform microwave (FTMW) spectroscopy of a supersonic molecular beam at centimetre wavelengths (13-37 GHz) and by using long-path absorption spectroscopy at millimetre and submillimetre wavelengths (127-925 GHz). The latter measurements include 91 transition frequencies for (28)Si(32)S, (28)Si(33)S, (28)Si(34)S, (29)Si(32)S and (30)Si(32)S in upsilon = 0, as well as 5 lines for (28)Si(32)S in upsilon = 1, with rotational quantum numbers J''< or = 52. The centimetre-wave measurements include more than 300 newly recorded lines. Together with previous data they result in almost 600 transitions (J'' = 0 and 1) from all twelve possible isotopic species, including (29)Si(36)S and (30)Si(36)S, which have fractional abundances of about 7 x 10(-6) and 4.5 x 10(-6), respectively. Rotational transitions were observed from upsilon = 0 for the least abundant isotopic species to as high as upsilon = 51 for the main species. Owing to the high spectral resolution of the FTMW spectrometer, hyperfine structure from the nuclear electric quadrupole moment of (33)S was resolved for species containing this isotope, as was much smaller nuclear spin-rotation splitting for isotopic species involving (29)Si. By combining the measurements here with previously published microwave and infrared data in one global fit, an improved set of spectroscopic parameters for SiS has been derived which include several terms describing the breakdown of the Born-Oppenheimer approximation. With this parameter set, highly accurate rotational frequencies for this important astronomical molecule can now be predicted well into the terahertz region.

Detection of low-frequency lambda-doublet transitions of the free 12CH and 13CH radicals

By Fourier transform microwave spectroscopy, lambda-doubling transitions of (12)CH and (13)CH in the lowest rotational levels of the X(2) product operator(1/2) ground state have been directly detected, which has not been done previously. For both radicals, hyperfine-split lines have been measured to an accuracy of better than 1 ppm between 3 and 15 GHz, an improvement of at least 2 orders of magnitude over previous laboratory data. The measured frequencies have been combined with all previous data for CH and (13)CH in the v = 0 level of the X(2) product operator electronic state to determine improved hyperfine parameters. The production of CH from various gases also has been studied and, with methanol, the yield of CH relative to OH. Astronomical studies of CH in higher rotational levels and (13)CH can now be undertaken on the basis of the present work.

Monobridged Si2H4

The rotational spectrum of a new monobridged isomer of Si(2)H(4), denoted here as H(2)Si(H)SiH, has been detected by Fourier transform microwave spectroscopy of a supersonic molecular beam through the discharge products of silane. On the basis of high-level coupled cluster theory, this isomer is calculated to lie only 7 kcalmol above disilene (H(2)SiSiH(2)), the most stable isomeric arrangement of Si(2)H(4), and to be fairly polar, with a calculated dipole moment of mu = 1.14 D. The rotational spectrum of H(2)Si(H)SiH exhibits closely spaced line doubling, characteristic of a molecule undergoing high-frequency inversion. Transition state calculations indicate that inversion probably occurs in two steps: migration of the bridged hydrogen atom to form silylsilylene, H(3)SiSiH, and then internal rotation of the SiH(3) group, followed by the reverse process. The potential energy surface for this type of inversion is quite shallow, with a barrier height of only 2-3 kcalmol. Searches for the rotational lines of silylsilylene, calculated to be of comparable stability to H(2)Si(H)SiH but about five times less polar (mu = 0.23 D), have also been undertaken, so far without success, even though strong lines of H(2)Si(H)SiH have been detected. The favorable energetics and high polarity of monobridged Si(2)H(4) with respect to either disilene or silylsilylene make it a plausible candidate for radioastronomical detection in sources such as IRC + 10216, where comparably large silicon molecules such as SiS, SiC(3), and SiC(4) have already been discovered.

Rotational spectra of the carbon-chain radicals HC5O, HC6O, and HC7O

Three new free carbon-chain radicals, HC5O, HC6O, and HC7O, and their deuterated isotopic species have been observed by Fourier transform microwave spectroscopy of a supersonic molecular beam. In contrast to the shorter HCnO radicals, these all have linear heavy-atom backbones and 2Pi electronic ground states. Like the isovalent HCnS radicals, the ground states of the HCnO radicals alternate with odd and even numbers of carbon atoms: those of HC5O and HC7O are 2Pi1/2 and that of HC6O is 2Pi3/2. From frequency measurements between 6 and 26 GHz, the rotational constant B, the centrifugal distortion constant D, and the lambda-type doubling and magnetic hyperfine constants have been determined to high precision for each chain. Predicted properties from coupled-cluster calculations are also reported for chains up to HC9O. The production of HCnO radicals for n even was highly favored when O2 was used as the source of oxygen, but those with n odd were best produced with CO.

Rotational spectroscopy and equilibrium structures of S3 and S4

The sulfur molecules thiozone S3 and tetrasulfur S4 have been observed in a supersonic molecular beam in the centimeter-wave band by Fourier transform microwave spectroscopy, and in the millimeter- and submillimeter-wave bands in a low-pressure glow discharge. For S3 over 150 rotational transitions between 10 and 458 GHz were measured, and for S4 a comparable number between 6 and 271 GHz. The spectrum of S3 is reproduced to within the measurement uncertainties by an asymmetric top Hamiltonian with three rotational and 12 centrifugal distortion constants; ten distortion constants, but an additional term to account for very small level shifts caused by interchange tunneling, are required to reproduce to comparable accuracy the spectrum of S4. Empirical equilibrium (r(e)(emp)) structures of S3 and S4 were derived from experimental rotational constants of the normal and sulfur-34 species and vibrational corrections from coupled-cluster theory calculations. Quantum chemical calculations show that interchange tunneling occurs because S4 automerizes through a transition state with D2h symmetry which lies about 500 cm(-1) above the two equivalent C2upsilon minima on the potential energy surface.

Fourier transform microwave spectroscopy of vinyldiacetylene, vinyltriacetylene, and vinylcyanodiacetylene

The rotational spectra of the three carbon chain molecules vinyldiacetylene (hex-1-ene-3,5-diyne, C(6)H(4)), vinyltriacetylene (oct-1-ene-3,5,7-triyne, C8H4), and its cyano analog vinylcyanodiacetylene (1-cyanohex-5-ene-1,3-diyne, C7H3N) have been observed for the first time by Fourier transform microwave spectroscopy of a supersonic molecular beam. The molecules were observed as products of an electrical discharge through selected precursor mixtures: ethylene/diacetylene and vinylacetylene/diacetylene for the pure hydrocarbon molecules and vinylacetylene/cyanoacetylene for vinylcyanodiacetylene. The measurements yield precise sets of rotational constants that compare very well with theoretical constants obtained by quantum chemical calculations at the B3LYP/cc-pVTZ level of theory. Since these three carbon chains are similar in structure and composition to known astronomical molecules and because of their significant polarity, all three are candidates for radio astronomical detection.

Rotational spectrum and carbon-13 hyperfine structure of the C3H, C5H, C6H, and C7H radicals

By means of Fourier transform microwave spectroscopy of a supersonic molecular beam, we have detected the singly substituted carbon-13 isotopic species of C(5)H, C(6)H, and C(7)H. Hyperfine structure in the rotational transitions of the lowest-energy fine structure component ((2)Pi(12) for C(5)H and C(7)H, and (2)Pi(32) for C(6)H) of each species was measured between 6 and 22 GHz, and precise rotational, centrifugal distortion, Lambda-doubling, and (13)C hyperfine coupling constants were determined. In addition, resolved hyperfine structure in the lowest rotational transition (J = 32-->12) of the three (13)C isotopic species of C(3)H was measured by the same technique. By combining the centimeter-wave measurements here with previous millimeter-wave data, a complete set of (13)C hyperfine coupling constants were derived to high precision for each isotopic species. Experimental structures (r(0)) have been determined for C(5)H and the two longer carbon-chain radicals, and these are found to be in good agreement with the predictions of high-level coupled-cluster calculations. C(3)H, C(5)H, and C(7)H exhibit a clear alternation in the magnitude and sign of the (13)C hyperfine coupling constants along the carbon-chain backbone. Because the electron spin density is nominally zero at the central carbon atom of C(3)H, C(5)H, and C(7)H, and at alternating sets of carbon atoms of C(5)H and C(7)H, owing to spin polarization, almost all of the (13)C coupling constants at these atoms are small in magnitude and negative in sign. Spin-polarization effects are known to be important for the Fermi-contact (b(F)) term, but prior to the work here they have generally been neglected for the hyperfine terms a, c, and d.

Laser spectroscopy of Si3C

The C 1B1<--X 1A1 band system of the potential interstellar species Si3C has been recorded in a silane/acetylene discharge by resonant two-color two-photon ionization spectroscopy. The origin band is located near 24,925 cm-1 (3.09 eV). Several other features in the spectrum are assigned to progressions in the Si-Si stretching modes as well as to sequence and hot band transitions. The assignment was facilitated by ab initio calculations, which also indicate that this is the strongest electronic transition of Si3C in the visible region of the spectrum. Features in the spectrum are broadened considerably (ca. 10 cm-1), and suggest an excited state lifetime of a few picoseconds. Possible reasons for the short-lived nature of the excited state are discussed.

Tetrasulfur, S4: Rotational spectrum, interchange tunneling, and geometrical structure

The rotational spectrum of S4 has been observed for the first time in an electrical discharge through sulfur vapor. Two techniques have been used: Fourier transform microwave spectroscopy and long-path millimeter-wave absorption spectroscopy. Small, but systematic shifts of the measured transition frequencies of the normal isotopic species indicate that S4 has C2v symmetry but with a low-lying transition state of D2h symmetry, yielding interchange tunneling at 14.1(2) kHz in its ground vibrational state. From the rotational constants of the normal and the single 34S isotopic species, an experimental (r0) structure has been derived: S4 is a singlet planar trapezoid with a terminal bond length of 1.899(7) A, a central bond of 2.173(32) A, and an S-S-S angle of 103.9(8) degrees. Like thiozone (S3), S4 is a candidate for detection in the atmosphere of the Jovian moon Io and in other astronomical sources.

Mono- and Dibridged Isomers of Si2H3 and Si2H4: the True Ground State Global Minima. Theory and Experiment in Concert

Highly correlated ab initio coupled-cluster theories (e.g., CCSD(T), CCSDT) were applied on the ground electronic states of Si(2)H(3) and Si(2)H(4), with substantive basis sets. A total of 10 isomers, which include mono- and dibridged structures, were investigated. Scalar relativistic corrections and zero-point vibrational energy corrections were included to predict reliable energetics. For Si(2)H(3), we predict an unanticipated monobridged H(2)Si-H-Si-like structure (C(s), (2)A'') to be the lowest energy isomer, in constrast to previous studies which concluded that either H(3)Si-Si (C(s), (2)A'') or near-planar H(2)Si-SiH (C(1), (2)A) is the global minimum. Our results confirm that the disilene isomer, H(2)Si-SiH(2), is the lowest energy isomer for Si(2)H(4) and that it has a trans-bent structure (C(2)(h), (1)A(g)). In addition to the much studied silylsilylene, H(3)Si-SiH, we also find that a new monobridged isomer H(2)Si-H-SiH (C(1), (1)A, designated 2c) is a minimum on the potential energy surface and that it has comparable stability; both isomers are predicted to lie about 7 kcal/mol above disilene. By means of Fourier transform microwave spectroscopy of a supersonic molecular beam, the rotational spectrum of this novel Si(2)H(4) isomer has recently been measured in the laboratory, as has that of the planar H(2)Si-SiH radical. Harmonic vibrational frequencies as well as infrared intensities of all 10 isomers were determined at the cc-pVTZ CCSD(T) level.

Rotational spectrum and structure of Si3

The rotational spectrum of a pure silicon cluster, the Si3 trimer, has been observed for the first time. From the rotational constants of the normal and the 29Si and 30Si isotopic species, a precise geometrical structure has been derived: the trimer is an isosceles triangle with a bond to the apex Si of length 2.177(1) A and an apex angle of 78.10(3) degrees. The substantial inertial defect and fairly large centrifugal distortion suggest that the molecule possesses a shallow bending potential. Si3 is a good candidate for astronomical detection because radio lines of comparably massive silicon molecules (e.g., SiC2, SiC4, and SiS) are readily observed in at least one astronomical source. The rotational spectra of Si6, Si9, and even larger polar silicon clusters may be detectable with the present technique, as well as similar germanium clusters.

Facial fractures in a level I trauma centre: the importance of protective devices and alcohol abuse

Urban trauma centres have recently noted a shift in the causative mechanism of facial fractures away from motor vehicle crashes (MVC) to blunt assaults (BA). This study was conducted to examine the incidence and aetiology of facial fractures at our institution as well as the relationship with alcohol and protective device use. Trauma registry records of all patients admitted to a level I trauma centre from 1 January 1988 to 1 January 1999 were reviewed. There were 13594 trauma admissions during the 11-year period. Facial fractures were sustained by 1429 patients (10.5%) and this group forms the subject of this study. MVC was the predominant aetiology (59.9%) followed by BA (18.8%). Facial fractures were found in 9.5% of restrained MVC patients compared to 15.4% of unrestrained patients (P<0.00l). Non-helmeted motorcyclists were four times more likely to sustain facial fractures (4.3% vs. 18.4%) than helmeted patients (P<0.00l). 39.6% of patients in the MVC group were legally intoxicated compared to 73.5% in the BA group (P<0.00l). 45.4% of unrestrained patients with facial fractures were intoxicated compared to 11.8% of restrained MVC patients with facial fractures (P<0.001). MVC continue to be the primary aetiology of facial fractures in our trauma population. Protective devices decrease the incidence of facial fractures. Lack of protective device use and the consumption of alcohol correlate with sustaining facial fractures.

Carbon chains and rings in the laboratory and in space

Seventy-seven reactive organic molecules of astrophysical interest have been identified in a supersonic molecular beam, 73 in the radio band by Fourier-transform microwave spectroscopy, four in the optical by laser cavity ringdown spectroscopy. Most are linear carbon chains, but six consist of carbon chains attached to the compact, highly polar C3 ring, and two are rhomboidal cyclic configurations of SiC3. The laboratory astrophysics of the radio molecules is complete for the time being, in the sense that essentially all the rotational transitions of current interest to radio astronomy (including hyperfine structure when present) can now be calculated to a small fraction of 1 km s(-1) in equivalent radial velocity; six of the radio molecules have already been detected in space on the basis of the present data. The FTM spectrometer employed in this work is far from fundamental limits of sensitivity, so many more molecules can probably be found by refinements of present techniques. The density of reactive molecules in our supersonic beam is generally high by the standards of laser spectroscopy, and many of the radio molecules probably have detectable optical transitions which we are attempting to find, largely motivated by the long-standing problem of the diffuse interstellar bands. Our most interesting result to date is the detection of a fairly strong molecular band at 443 nm in a benzene discharge, in exact coincidence with the strongest and best known interstellar band. Isotopic shifts measured with partially and totally deuterated benzene suggest that the carrier of the laboratory band is a hydrocarbon molecule with the elemental formula CnH5, with n most likely in the range 3-6.

Experimental Structures of the Carbon Chains HC(7)N, HC(9)N, and HC(11)N by Isotopic Substitution

The effective structures (r(0)) of the three linear cyanopolyynes HC(7)N, HC(9)N, and HC(11)N have been determined to high accuracy by isotopic substitution, following detection in a supersonic molecular beam with a Fourier transform microwave spectrometer of all of the singly substituted rare isotopic species. For each chain, the lengths of the individual bonds have been determined to an accuracy of 0.001 Å or 0.1% toward the end of the chain and to 0.01 Å or 1.0% toward the center. The experimental structures are in excellent agreement with recent high-level theoretical calculations, or, in the case of HC(11)N, with extrapolation from HC(9)N. The three polyynes studied here represent the largest reactive carbon chain molecules for which accurate structures have been derived empirically. For HC(7)N and HC(9)N, it has been possible to resolve at high-resolution nitrogen hyperfine structure in the lower rotational transitions and determine eQq for all of the singly substituted isotopic species of HC(7)N and for normal HC(9)N. Copyright 2000 Academic Press.

The Radio Spectra of SiCCH, SiCN, and SiNC

Three new silicon-bearing radicals of astrophysical interest, SiCCH and the two nearly isoenergetic isomers SiCN and SiNC, were detected in a laboratory discharge in their X2Pi ground states by Fourier transform microwave and millimeter-wave absorption spectroscopy. Hyperfine structure was observed in the low rotational transitions of the (2)Pi(1/2) ladder, and well-resolved Lambda-doubling was observed in both fine-structure ladders. With the spectroscopic constants derived from the laboratory measurements, the spectra of all three can be calculated to an uncertainty of less than 0.1 km s(-1) in equivalent radial velocity over the entire range of interest to radio astronomers. SiCN, with a dipole moment of 2.9 D, is probably the most promising of the three for astronomical discovery.

Immunity to onchocerciasis: cells from putatively immune individuals produce enhanced levels of interleukin-5, gamma interferon, and granulocyte-macrophage colony-stimulating factor in response to Onchocerca volvulus larval and male worm antigens

Antigen-specific interleukin-5 (IL-5), gamma interferon (IFN-gamma), and granulocyte-macrophage colony-stimulating factor (GM-CSF) responses in individuals living in an area of hyperendemicity for onchocerciasis in Cameroon were examined. The responses against antigens prepared from Onchocerca volvulus third-stage larvae (L3), molting L3 (mL3), and crude extract from adult males (M-OvAg) were compared to the responses against antigens from adult female worms and skin microfilariae. Cytokine responses for the putatively immune individuals (PI) and the infected individuals (INF) were compared. A differential cytokine profile of IL-5 (Th2 phenotype) and IFN-gamma (Th1 phenotype) was found in these individuals in response to the antigens. In both the PI and the INF, Th2 responses against all the antigens tested were dominant. However, in the PI group as a whole, there was an enhanced Th2 response against the larval antigens and the adult male and adult female antigens, and a Th1 response in a subgroup of the PI (27 to 54.5%) against L3, mL3, and M-OvAg antigens was present. While the PI produced significantly higher levels of GM-CSF against L3, mL3, and M-OvAg antigens than the INF, there was no difference in the GM-CSF responses of the groups against the other antigens. The present study indicated that, in comparison to the INF, the PI have distinct larva-specific and adult male-specific cytokine responses, thus supporting the premise that immunological studies of the PI would lead to the identification of immune mechanisms and the target genes that play a role in protective immunity.

Laboratory Detection of a Molecular Band at lambda4429

A fairly strong molecular absorption band at 4429.27+/-0.04 Å, closely centered on the strongest diffuse interstellar band at 4428.9+/-1.4 Å, has been found in a supersonic molecular beam among the products of a discharge through benzene and other hydrocarbons. This agreement in wavelength to a few parts in 104 strongly suggests a common carrier. The width of the laboratory band is significantly less than that of the diffuse interstellar band, but this difference may be the result of the very low rotational temperature in the supersonic beam-possibly as low as 2 K-relative to that of a weakly polar molecule in the diffuse interstellar gas (100-200 K). Several candidate carriers are discussed. Two of the more promising are the allyl cation C3H+5 and the dimethylene allenyl radical C5H5, both bent carbon chains that may be close enough to linear to reconcile the puzzling appearance of P-, Q-, and R-branches in the laboratory band with the five hydrogen atoms suggested by the observed deuterium isotopic shifts.

Pressure control inverse ratio ventilation in the treatment of adult respiratory distress syndrome in patients with blunt chest trauma

The objective of this study was to evaluate the efficacy of pressure control inverse ratio ventilation (PCIRV) in improving oxygenation in trauma patients with adult respiratory distress syndrome (ARDS) and to assess the potential risks associated with this form of treatment. This was a cohort study assessing the trends in hemodynamic and ventilatory parameters after the initiation of PCIRV, conducted at a community Level I trauma center intensive care unit. The study comprised 15 trauma patients developing severe, progressive ARDS [two or more of the following criteria: positive end-expiratory pressure (PEEP) >10 cm H2O; arterial partial pressure of oxygen divided by fraction of inspired oxygen (PaO2:FiO2) ratio <150; and peak inspiratory pressure (PIP) >45 cm H2O]: ten due to blunt chest injuries, three due to sepsis, and two due to fat emboli syndrome. PCIRV was initiated. Main outcome measures were PIP, PEEP (total, auto), oxygen saturation, cardiac index, oxygen delivery, PaO2:FiO2 ratio, compliance, evidence of complications of PCIRV, and mortality. Within 24 hours of conversion to PCIRV, the patients stabilized and the mean PaO2:FiO2 ratio rose from 96.3+/-57.8 to 146.8+/-91.1 (P<0.05) and PIP fell from 47.9+/-13.8 to 38.8+/-8.4 cm H2O; auto-PEEP increased from 0.5+/-1.9 to 7.5+/-5.6 cm H2O (P<0.05); oxygen delivery index remained stable (563+/-152 to 497+/-175 mL/min/m2); three patients developed evidence of barotrauma, one patient developed critical illness polyneuropathy, and two patients died (13%). PCIRV is an effective salvage mode of ventilation in patients with severe ARDS, but it is not without complications. Auto-PEEP levels and cardiac index should be monitored to ensure tissue oxygen delivery is maintained.