Case Of HH Research Articles

On dynamical gaskets generated by rational maps, Kleinian groups, and Schwarz reflections

According to the Circle Packing Theorem, any triangulation of the Riemann sphere can be realized as a nerve of a circle packing. Reflections in the dual circles generate a Kleinian group H H whose limit set is a generalized Apollonian gasket Λ H \Lambda _H . We design a surgery that relates H H to a rational map g g whose Julia set J g \mathcal {J}_g is (non-quasiconformally) homeomorphic to Λ H \Lambda _H . We show for a large class of triangulations, however, the groups of quasisymmetries of Λ H \Lambda _H and J g \mathcal {J}_g are isomorphic and coincide with the corresponding groups of self-homeomorphisms. Moreover, in the case of H H , this group is equal to the group of Möbius symmetries of Λ H \Lambda _H , which is the semi-direct product of H H itself and the group of Möbius symmetries of the underlying circle packing. In the case of the tetrahedral triangulation (when Λ H \Lambda _H is the classical Apollonian gasket), we give a quasiregular model for the above actions which is quasiconformally equivalent to g g and produces H H by a David surgery. We also construct a mating between the group and the map coexisting in the same dynamical plane and show that it can be generated by Schwarz reflections in the deltoid and the inscribed circle.

Mosaic variants detectable in blood extend the clinicogenetic spectrum of GLI3-related hypothalamic hamartoma

PurposeHypothalamic hamartoma (HH) can be syndromic (eg, Pallister-Hall syndrome [PHS], HH, and mesoaxial polydactyly) or nonsyndromic. Most PHS cases have germline variants in GLI3, but a minority remain unresolved. Some nonsyndromic HH cases have GLI3 mosaic variants in the brain. PHS and nonsyndromic HH are regarded as 2 separate GLI3-related disorders, clinically and genetically. Here, we searched for mosaic variants in unsolved cases. MethodsHigh-depth exome sequencing was performed on leukocyte-derived DNA in 1 unsolved PHS and 25 nonsyndromic HH cases. We searched for mosaic variants in GLI3 and other HH-associated genes. Mosaic variants were confirmed by droplet-digital polymerase chain reaction. ResultsThe PHS case had a GLI3 stop-gain variant c.2845G>T; p.(Glu949Ter) at 6.9% variant allele fraction (VAF). Two nonsyndromic cases had GLI3 variants—a stop-gain (c.2639C>A; p.(Ser880Ter), VAF 3.7%) and a frameshift (c.3326_3330del; p.(Glu1109AlafsTer18), VAF 7.8%). The nonsyndromic patient with 3.7% VAF in blood had 35.8% VAF in HH tissue. He had a vestigial extra digit removed adjacent to his left fifth finger. ConclusionGLI3 mosaicism is associated with a phenotypic spectrum from PHS to HH with subtle extra PHS features, to isolated nonsyndromic HH. High-depth sequencing permits detection of low-level mosaicism, which is an important cause of both syndromic and nonsyndromic HH.

Clinical characteristics and molecular genetic analysis of a cohort with idiopathic congenital hypogonadism.

Hypogonadism is defined as inadequate sex hormone production due to defects in the hypothalamic-pituitary-gonadal axis. In recent years, rare single gene defects have been identified in both hypergonadotropic hypogonadism (Hh), and hypogonadotropic hypogonadism (HH) cases with no chromosomal anomalies. The aim of the present study is to investigate the underlying molecular genetic etiology and the genotype-phenotype relationship of a series of patients with Hh and HH. In total, 27 HH and six Hh cases were evaluated. Clinical and laboratory features are extracted from patients' hospital files. Whole exome sequencing (WES) analysis was performed. A total of 27 HH cases (15 female) (mean age: 15.8±2.7 years) and six Hh patients (six females) (mean age: 14.9±1.2 years) were included. In molecular genetic analysis, a pathogenic/likely pathogenic variant was identified in five (two patients from the same family) of 27 HH cases (two novel) and three of the six Hh. In HH group variants (pathogenic, likely pathogenic and variant of uncertain significance) were identified in KISS1R (n=2), PROK2 (n=1), FGFR1 (n=1), HS6ST1 (n=1), GNRH1 (n=1) genes. In the Hh group, splice-site mutations were detected in DCAF17 (n=1) and MCM9 (n=2) genes. HH and Hh cases are genetically heterogeneous diseases due to oligogenic inheritance, incomplete penetrance, and variable expressivity. We found rare variants in CHH related genes in half of our HH cases, whereas they classified as pathogenic/likely pathogenic according to ACMG criteria in only about 15% of HH cases. Using advanced genetic analysis methods such as whole-genome sequencing and long-read sequencing may increase the mutation detection rate, which should always be associated with and expert genetic counseling to interpret the data.

Prognostic Value of DNA Ploidy By Flow Cytometry for Pediatric B-Cell Acute Lymphoblastic Leukemia: A Peruvian Cohort Study

Background: B-cell Acute Lymphoblastic Leukemia (B-ALL) represents an aggressive malignancy but highly curable in children. Currently, pediatric collaborative clinical trials have reported survival rates that exceed 90%, and DNA ploidy by flow cytometry (FC) has been pointed for risk stratification and prognosis in these clinical trials. However, its generalized use remains controversial as few studies reported no impact in real-world populations. We aimed to evaluate prognostic value of DNA ploidy measured by FC in a large cohort of Peruvian children with B-ALL. Methods: We evaluated prospectively DNA-ploidy by FC in bone marrow diagnostic samples from newly diagnosed children (<15 years) with B-ALL treated at Instituto Nacional de Enfermedades Neoplasicas (Lima-Peru) between 2017-2019. DNA-ploidy was evaluated using Propidium Iodide and calculated as the mean ratio between fluorescence of pathologic B blasts and normal marrow cells. Ploidy categories were established based on previous reports of DNA-index(DI): Diploid + Low-Hyperdiploidy (DLH; DI: 0.95 - 1.15), hypo-diploid (HD; DI<0.95) and High-hyperdiploidy (HH; DI>1.15), and recalculated using maximally selected rank statistics. Samples were analyzed in a FacsCanto II flow cytometer (BD) and Infinicyt software (Cytognos). All patients received BFM-2009 protocol and had minimal residual disease evaluation at the end of IA and IB induction. Minimal residual disease (MRD) was evaluated with FC using a detection threshold of 0.0025% and considering positive ≥0.01%. Survival curves (event-free and overall survival) were estimated using the Kaplan-Meier method and compared with the Log-rank test. Results: A total of 192 children were included (2 HD, 141 DLH and 49 HH cases according to DNA ploidy by FC). Clinical characteristics and outcomes are shown in Table 1. Median age at diagnosis was 5 years (Range:1-14), 10 years for HD, 6 and 3 years for DLH and HH, respectively (p=0.002). F/M ratio was 1:1.3 for all cases, but 1:2 in HH group. Most karyotypes (62%) had unsatisfactory or poor-quality result, 29% were considered normal, and only 9 hyperdiploidy and 2 hypodiploidy cases were detected by conventional karyotyping. Regarding genetics, 21 TEL/AML, 19 E2A/PBX1 and 9 BCR/ABL cases were detected by multiplex-PCR and most balanced alterations had DLH subtype and only one HD case had TEL/AML. MRD positivity after Induction IA was 35% without difference between groups (50% HD, 36% DLH and 31% HH, p=0.77), however after Induction IB, MRD was positive in 50% of HD, 12% of DLH and 5% of HH (p=0.048). At eight-teen months of follow-up, one relapse was seen in HD cases, and 11% DLH and 10% in HH. Median EFS and OS was not reached, however one-year EFS and OS were 86% for both without significant differences between groups. Multivariate analysis showed that MRD positivity remains as the principal independent prognostic factor and ploidy by DNA did not show any impact in terms of MRD, EFS and OS. Conclusion: High-Hyperdiploidy by DNA ploidy was associated to better MRD negativity rate after induction IB but without impact in short-term EFS and OS. DNA ploidy did not represent a prognostic factor in our study cohort, however long-term follow-up is warranted. Additionally, a better genetic risk stratification is necessary to improve outcomes in Latino high-risk population. Disclosures No relevant conflicts of interest to declare.

Reanalysis of the Tilt MTFs Based on the C-Band Empirical Geophysical Model Function

The tilt modulation is one of the key factors affecting sea wave inversion accuracy based on some microwave sensors such as SAR, microwave spectrometer, and so on. Up to now, the traditional tilt modulation-transfer functions (MTFs) based on the Bragg scattering model and Phillips spectrum have been used in the sea wave spectrum retrieval algorithm for microwave sensors operating at medium incident angles. The traditional tilt MTFs are only related to radar polarization and incident angle, but not affected by wind speed and wind direction. However, the values of the tilt MTFs evaluated on the basis of the C-band empirical geophysical model function (GMF) CMOD5.na demonstrate that wind speed and wind direction also have significant effects on the tilt MTFs. In addition, the comparisons show that the values of the traditional tilt MTFs for both HH (horizontal) and VV (vertical) polarization cases are obviously smaller, which indicates that the traditional tilt MTFs would underestimate the influence of the local incident angle change on the scattering fields. On the other hand, the difference between the horizontal and the vertical polarization tilt MTFs, however, is overestimated by the traditional tilt MTFs. Finally, by fitting the data evaluated based on the C-band empirical GMF, we propose new tilt MTFs, which can overcome the shortcomings of the traditional tilt MTFs.

Clinical and genetic features of 64 young male paediatric patients with congenital hypogonadotropic hypogonadism.

The diagnosis of congenital hypogonadotropic hypogonadism (CHH) in prepuberty has always been challenging. Here, we aimed at studying the clinical and genetic features of paediatric CHH, especially the phenotype of hypospadias and dual defects (patients showing hypothalamic and/or pituitary defects and testicular hypoplasia), so as to have a better understanding of CHH. The clinical and genetic features of patients with CHH were analysed, and the relationships between hypospadias, dual defects and genetics were investigated. Patients who visited Beijing Children's Hospital and were positively diagnosed with CHH. The collected data included sex hormones, MRI of the olfactory bulb, human chorionic gonadotrophin (hCG) test and genetic testing. We analysed clinical features and genetic results, especially hypospadias and dual defects, and compared the stimulated testosterone (T) levels in patients with and without cryptorchidism. Sixty-four patients were positively diagnosed, and forty-seven (73.4%) had Kallmann syndrome (KS). Four patients (6.3%) had hypospadias, including 2 KS. Micropenis combined with cryptorchidism was the most common phenotype (39%). Approximately two-third of patients showed a poor response to hCG; 15 cases were diagnosed with dual defects, and there were no significant differences between those with and without cryptorchidism. Twenty-six cases (51%) of 51 patients were identified as having classical HH mutations, affecting 10 different genes, with oligogenic mutations in 5 cases (9.8%). The most common mutations were in PROKR2 (17.6%), FGFR1 (13.7%) and CHD7 (7.8%). The frequency of PROKR2 mutations was higher in dual HH when compared to other HH cases (6/15 vs 3/36, P=.021). Micropenis and/or cryptorchidism can serve as important signs for the diagnosis of HH in paediatrics, and the coexistence of hypospadias does not exclude the diagnosis of CHH, including KS or normosmic isolated HH (nHH). Testicular function may be impaired earlier than expected, and PROKR2 mutations need to be evaluated to identify presumed dual defects.

Home Health Nursing Care and Hospital Use for Medically Complex Children.

Home health nursing care (HH) may be a valuable approach to long-term optimization of health for children, particularly those with medical complexity who are prone to frequent and lengthy hospitalizations. We sought to assess the relationship between HH services and hospital use in children. Retrospective, matched cohort study of 2783 hospitalized children receiving postdischarge HH services by BAYADA Home Health Care across 19 states and 7361 matched controls not discharged to HH services from the Children's Hospital Association Case Mix database between January 2004 and September 2012. Subsequent hospitalizations, hospital days, readmissions, and costs of hospital care were assessed over the 12-month period after the initial hospitalization. Nonparametric Wilcoxon signed rank tests were used for comparisons between HH and non-HH users. Although HH cases had a higher percentage of complex chronic conditions (68.5% vs 65.4%), technology assistance (40.5% vs 35.7%), and neurologic impairment (40.7% vs 37.3%) than matched controls (P ≤ .003 for all), 30-day readmission rates were lower in HH patients (18.3% vs 21.5%, P = .001). At 12 months after the index admission, HH patients averaged fewer admissions (0.8 vs 1.0, P < .001), fewer days in the hospital (6.4 vs 6.6, P < .001), and lower hospital costs ($22 511 vs $24 194, P < .001) compared with matched controls. Children discharged to HH care experienced less hospital use than children with similar characteristics who did not use HH care. Further investigation is needed to understand how HH care affects the health and health services of children.

“Symptomatic” infection-associated acute encephalopathy in children with underlying neurological disorders

BackgroundDevelopment of infection-associated acute encephalopathy (AE) is precipitated by several factors, including viral agents, age, and genetic polymorphisms. In addition, children with prior underlying neurological disorders can also present with AE. MethodWe reviewed 55 children with AE who were referred to hospitals participating in the Status Epilepticus Study Group from 1988 to 2013. AE was classified into eight subtypes: acute encephalopathy with biphasic seizures and late reduced diffusion (AESD); hemiconvulsion–hemiplegia syndrome (HH); acute necrotizing encephalopathy; hemorrhagic shock and encephalopathy syndrome (HSES); clinically mild encephalitis/encephalopathy with a reversible splenial lesion; acute encephalitis with refractory, repetitive partial seizures; Reye-like syndrome; and unclassified. ResultOf the 55 AE cases, 14 (25.4%) had underlying neurological disorders, including perinatal insults (n=6) and genetic syndrome and/or brain malformations (n=8). These preceding morbidities were relatively common in AESD (6/18, 33.3%), HH (3/9, 33.3%), and HSES (3/6, 50.0%). History of epilepsy or febrile seizures were frequent in HH cases (4/9, 44.4%), whereas they were rare in other AE subtypes. ConclusionAmong the AE subgroups, HH, HSES, and AESD frequently emerged in preceding etiologies with augmented neuronal excitability. These subgroups may have distinct pathomechanism from the “cytokine storm” mediated AEs during childhood.

Long-Term Follow-Up Study of Biliary Reconstructions and Complications After Adult Living Donor Liver Transplantation.

The aim of this study was to analyze the feasibility of duct-to-duct biliary reconstruction (hepaticohepaticostomy) with a T-tube stent (HH-T) after adult living donor liver transplantation (LDLT) based on long-term follow-up. We retrospectively evaluated 89 primary adult LDLTs who had survived 1 month from March 1999 to March 2012.There were 46 men and 43 women. Overall median age of the recipients was 54 years (range, 17-70 years). Indications for LDLT were hepatocellular carcinoma(n = 28), fulminant hepatic failure (n = 15), cholestatic liver disease (including primary biliary cirrhosis and primary sclerosing cholangitis; n=15), viral hepatitis (n = 10), metabolic liver disease(n = 7), Budd-Chiari syndrome (n = 3), and other etiologies(n = 11). We compared the incidence of bile leaks and biliary strictures (BS) in 3 groups of patients:Roux-en-Y hepaticojejunostomy (HJ; n = 26); duct-to-duct hepaticohepaticostomy with external stents except a T-tube (HH; n = 35); and HH-T (n = 28). Median follow-up was longer among the HH (81 months) than the other groups (63 months in HJ and 48 months in HH-T). Bile leaks developed in 7 of the HJ cases (27%); 6 of the HH cases (17%); and 2 of the HH-T cases (6%; P = .13). All cases with bile leaks (n = 15) were treated using continuous drainage, 12 of them (80%) successfully. BS developed in 4 HJ cases (22%); 8 HH cases (23%), and 4 HH-T cases (14%; P = .57). Intervention for BS (n = 20) was successful in 10 cases (50%) via an endoscopic approach and 6 cases (30%) via a percutaneous transhepatic approach. Operative management for BS was required in 4 cases (20%). Biliary reconstruction using HH-T may be effective to prevent bile leaks after LDLT. However, HH-T may not decrease the incidence of BS after adult LDLT.

Long-Term Follow-up Study of Biliary Reconstructions and Complications After Adult Living Donor Liver Transplantation: Feasibility of Duct-to-Duct Reconstruction With a T-Tube Stent

The aim of this study was to analyze the feasibility of duct-to-duct biliary reconstruction (hepaticohepaticostomy) with a T-tube stent (HH-T) after adult living donor liver transplantation (LDLT) based on long-term follow-up. We retrospectively evaluated 63 primary adult LDLTs who had survived >1 month from March 1999 to January 2008. We compared the incidence of bile leaks and biliary strictures (BS) in 3 groups of patients: Roux-en-Y hepaticojejunostomy (HJ; n = 18); duct-to-duct hepaticohepaticostomy with external stents except a T-tube (HH; n = 26); and HH-T (n = 19). Median follow-up was longer among the HJ (63 months) than the other groups (32 months in HH and 25 months in HH-T; P = .04). Bile leaks developed in 8 of the HJ cases (44%); 9 of the HH cases (33%); and 1 of the HH-T cases (5%; P = .02). All cases with bile leaks (n = 18) were treated using continuous drainage, 15 of them (83%) successfully. BS developed in 4 HJ cases (22%); 12 HH cases (46%), and 4 HH-T cases (21%; P = .12). Intervention for BS (n = 20) was successful in 10 cases (50%) via an endoscopic approach and 6 cases (30%) via a percutaneous transhepatic approach. Operative management for BS was required in 4 cases (20%). Biliary reconstruction using HH-T may be effective to prevent bile leaks after LDLT. However, HH-T may not decrease the incidence of BS after adult LDLT.

Time-Domain Electromagnetic Fields Radiating Along the Horizontal Interface Between Vertically Uniaxial Half-Space Media

At the horizontal interface between vertically uniaxial half-space media, the propagation of electromagnetic fields is theoretically investigated for an interfacial impulse current source of infinitesimal size. For the electric field, the problem divides into the horizontal source and horizontal receiver (HH), vertical source and vertical receiver (VV), horizontal source and vertical receiver (HV), and vertical source and horizontal receiver (VH) cases. Employing the interface scheme of the Cagniard-style analysis, the solutions of the HH and VV cases are obtained in exact explicit forms. The solutions of the HV and VH cases cannot be expressed in integral-free forms, but the impulse components implicit in the integral solutions can be analytically extracted without the aid of the frequency-domain asymptotic techniques. Investigation is also made of the magnetic field and of the variation of waveforms when the receiver is taken a little off the interface. The uniaxial case is a generalization of the isotropic case, affording richer information of the wave physics

Lobulocentricity of Breast Hypersecretory Hyperplasia With Cytologic Atypia

Intracytoplasmic and extracytoplasmic features of secretion, similar to lactational changes, occasionally are seen in the nonparous human breast, usually are lobulocentric, and often have aberrant cytologic and nuclear changes. In these “hypersecretory hyperplasias” (HHs; 38 women) there is bubbly cytoplasm with irregular apical cytoplasmic and/or nuclear protrusions. In a review of 138 HH cases the following additional associated changes were found: nuclear atypia (HHA, 22 women), atypical ductal hyperplasia (ADH-HH, 24 women), and ductal carcinoma in situ (DCIS-HH, 54 women). A diagnosis of DCIS-HH requires involvement of true duct(s) and of several contiguous lobular units, emphasizing the importance of extent and overall size and similar cytology and histologic arrangement of intercellular spaces indicating a homogeneous cell population. Cases of HH regularly are characterized as having adjacent and nearby lobular units with quite diverse cytologic patterns. The major impact of this study is to recognize that HHA may be regarded as having uncertain significance when found alone in the usual presentation in a single unit, but that formally defined ADH and/or DCIS may be locally present.

Lobulocentricity of Breast Hypersecretory Hyperplasia With Cytologic Atypia: Infrequent Association With Carcinoma In Situ

Intracytoplasmic and extracytoplasmic features of secretion, similar to lactational changes, occasionally are seen in the nonparous human breast, usually are lobulocentric, and often have aberrant cytologic and nuclear changes. In these "hypersecretory hyperplasias" (HHs; 38 women) there is bubbly cytoplasm with irregular apical cytoplasmic and/or nuclear protrusions. In a review of 138 HH cases the following additional associated changes were found: nuclear atypia (HHA, 22 women), atypical ductal hyperplasia (ADH-HH, 24 women), and ductal carcinoma in situ (DCIS-HH, 54 women). A diagnosis of DCIS-HH requires involvement of true duct(s) and of several contiguous lobular units, emphasizing the importance of extent and overall size and similar cytology and histologic arrangement of intercellular spaces indicating a homogeneous cell population. Cases of HH regularly are characterized as having adjacent and nearby lobular units with quite diverse cytologic patterns. The major impact of this study is to recognize that HHA may be regarded as having uncertain significance when found alone in the usual presentation in a single unit, but that formally defined ADH and/or DCIS may be locally present.

The structure and kinematics of the HH 444 photoionized jet in the σ Orionis region

HH 444 is a stellar jet which is immersed in the H II region photoionized by σ Orionis. Spatially resolved, high spectral resolution observations of the H α and [N II] λ λ 6548, 6584 lines have been obtained for this object. These observations reveal for the first time the detailed velocity structure of the stellar jet and its associated bow-shock. The line profiles are modeled with gasdynamic numerical simulations, using a 3D code that also includes the transfer of the ionizing radiation from an external source (i.e., σ Orionis for the case of HH 444). In order to reproduce the observed characteristics of the line profiles, we find that an axially peaked initial velocity profile for the jet and a non-zero initial opening angle for the flow with a time-variable ejection velocity is required. With these three ingredients we can reproduce the observed acceleration of the material along the jet beam, the rapid H α intensity drop for increasing distances from the source, and the knotty structure of the jet, respectively.

Apperceptive agnosia and face recognition

Are faces and objects recognized by separate visual recognition systems or might a single system subserve the recognition of both classes of input? Recognition of faces and objects by a single system predicts that prosopagnosics, who selectively lose the ability to recognize faces due to brain damage, should also lose the ability to recognize objects. Contrary to this prediction, case studies of prosopagnosia have reported intact object recognition. Further support for separate visual recognition systems comes from the case of HH reported here. Following a stroke involving the left posterior cortex, HH has a severe apperceptive visual agnosia for visually presented objects and an alexia for words. Yet, he shows relatively spared visual face processing. Such a performance pattern completes a double dissociation between face and object processing when coupled with prosopaganosia. More importantly, HH is the first apperceptive visual object agnosic to demonstrate spared face processing. The severity of his object-processing deficit is such that from the earliest levels in the visual processing hierarchy, distinct neural substrates must be responsible for processing some objects and faces. These results are discussed as support for Farah's model (Visual agnosia: disorders of object recognition and what they tell us about normal vision. Cambridge, MA: MIT Press, 1990) of object, face and word recognition.

Transient interactions between tiny interfacial antennas on half‐space lossless dielectric

The interfacial electric‐field interaction subdivides into four cases: the HH, VV, HV, and VH cases. For each case, we derive the impulse‐response solution of the interfacial electric field generated by an infinitesimal impulse current source at the same interface, using plane‐time Fourier transform and a variant scheme of the Cagniard‐de‐Hoop method. We show that it is possible to obtain exact explicit‐form solutions for the HH and VV cases, whereas we have to evaluate the electric fields only by numerical calculations for the HV and VH cases since the exact solutions are yet unavailable. Various aspects of the impulse‐response solutions, such as the impulse radiation characteristics and the transient responses to time‐Gaussian inputs, are investigated as well as the offset‐differentiated field characteristics for the HV and VH cases. We also discuss the effect of the lower‐medium loss on the transient waveforms and the effect of the interface that makes the interfacial interaction quite different from the interaction in free space.

Herbig-Haro Jets, CO Flows, and CO Bullets: The Case of HH 111

We have carried out high spatial resolution, 12'', CO J = 2-1 observations at the IRAM 30 m telescope of the molecular outflow in the HH 111 jet complex. The Herbig-Haro jet is found to coincide with a highly collimated CO flow, with two distinct velocities, possibly providing kinematic evidence that the CO flow surrounds the HH jet. A second well-defined bipolar molecular flow, at large angles to the principal flow axis, coincides with the HH 121 infrared flow that emanates from the (presumably binary) VLA driving source; the region thus harbors one of the rare quadrupolar molecular flows. Extremely high velocity CO is found toward the principal HH working surface at the same velocity as the optically emitting gas, whereas this emission is weak toward the Herbig-Haro jet. Since the inclination of the HH jet is known from optical observations to be 10° to the plane of the sky, we conclude that there is CO in the flow with space velocities of up to 500 km s-1! Further out, and precisely along the flow axis, we have discovered three equidistant CO bullets with space velocities of about 240 km s-1, which are not detected in the optical. We interpret these bullets as the result of earlier eruptions from the energy source that are now moving through an ambient medium so tenuous that no observable shock interaction takes place. Finally, we discuss the physical relation between the Herbig-Haro jet, the CO bullets, and the low-velocity molecular outflow. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

Ammonia Emission Downstream of the Herbig-Haro Object 1

view Abstract Citations (23) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ammonia Emission Downstream of the Herbig-Haro Object 1 Torrelles, J. M. ; Gomez, J. F. ; Ho, P. T. P. ; Anglada, G. ; Rodriguez, L. F. ; Canto, J. Abstract We report VLA D-configuration NH3(1, 1) and (2, 2) observations of Herbig-Haro Object 1 (HH 1). In direct analogy to the case of HH 2 (Torrelles et al. 1992b), we have found ammonia emission immediately adjacent to and downstream of HH 1. As in the case of HH 2, there is no evidence of any significant perturbation in terms of heating and broadening of the ammonia lines. This high degree of symmetry between the HH 1 and HH 2 ammonia clumps implies a causal physical relationship between the HH objects and the ammonia emission, discarding the possibility that these clumps are just ambient clumps projected by chance downstream of the HH objects. In particular, we think that there is the possibility that these clumps delineate nearby ambient gas whose ammonia emission is enhanced by some still unknown process related to the radiation field generated at the head of the jet of the VLA- 1 source. However, detailed theoretical calculations will be needed to investigate this possibility. We also detected two other clumps located to the southwest of HH 1. One of them, seen only in the (2, 2) line, coincides with an H2O maser, and its temperature (≳30 K) suggests that there might be a young star embedded in this clump. The other clump is located ∼15" south of the H2O maser. We also detected ammonia emission from the previously reported condensation associated with VLA-1 (Rodríguez et al. 1990a). As it was also previously reported, this condensation consists of two halves with a velocity shift of ∼2 km s-1 of the same direction and sign as those of the HH 1-2 optical outflow. However, on dynamical considerations, we argue that this shift could represent expanding or contracting motions of a flattened structure seen almost edge-on, rather than a molecular outflow of low collimation. Publication: The Astrophysical Journal Pub Date: November 1993 DOI: 10.1086/173343 Bibcode: 1993ApJ...417..655T Keywords: ISM: INDIVIDUAL ALPHANUMERIC: HH 1-2; ISM: JETS AND OUTFLOWS; ISM: MOLECULES; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (7)

Neutral winds from protostars

We present Arecibo 21 cm line observations of neutral winds associated with young stellar objects. We confirm the detection of fast neutral winds in HH 7-11 and in L1551. These two winds have been coarsely mapped along the CO outflow direction. For the case of HH 7-11, we find that the maximum velocity declines from 170 km s −1 at the center (SVS 13), to ∼135 km s −1 at a position displaced half a beam away from the center

A model for collimated outflows in molecular clouds and the case of HH 7–11

Collimated outflows of high-velocity gas, with typical scale lengths of 0.01–0.2 pc, are often observed to be associated with linear chains of optical emission knots1, sometimes connected by faint nebulosities. The flows have been ascribed to the interaction between an energetic wind ejected by a young stellar object and circumstellar material. However, none of the acceleration and collimation mechanisms proposed so far can easily account for the most peculiar properties of the outflows, namely the almost constant spacing between the knots, their radial motion and the abrupt velocity changes along the flow, well illustrated by the prototype we use for our modelling, HH 7–11. We suggest here a new interpretation of the phenomenon, based on flows in a channel of variable cross-sectional area due to Kelvin–Helmholtz instabilities between the flow and the ambient medium; and present solutions of the Mach number equation for such a channel, which possess multiple critical points and shocks identified with the observed optical knots.