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PubMed2006

Natural electroweak breaking from a mirror symmetry.

We present "twin Higgs models," simple realizations of the Higgs boson as a pseudo Goldstone boson that protect the weak scale from radiative corrections up to scales of order 5-10 TeV. In the ultraviolet these theories have a discrete symmetry which interchanges each standard model particle with a corresponding particle which transforms under a twin or a mirror standard model gauge group. In addition, the Higgs sector respects an approximate global symmetry. When this global symmetry is broken, the discrete symmetry tightly constrains the form of corrections to the pseudo Goldstone Higgs potential, allowing natural electroweak symmetry breaking. Precision electroweak constraints are satisfied by construction. These models demonstrate that, contrary to the conventional wisdom, stabilizing the weak scale does not require new light particles charged under the standard model gauge groups.

Journal Article↗
PubMed2006

Observation of 54Ni: cross-conjugate symmetry in f7/2 mirror energy differences.

Gamma decays from excited states up to Jpi=6+ in the N=Z-2 nucleus 54Ni have been identified for the first time. Level energies are compared with those of the isobars 54Co and 54Fe and of the cross-conjugate nuclei of mass A=42. The good but puzzling f7/ cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.

Journal Article↗
PubMed2003

Photosynthesis and growth of tobacco with a substituted bacterial Rubisco mirror the properties of the introduced enzyme.

Complete replacement, by biolistic plastid transformation, of the hexadecameric ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of tobacco (Nicotiana tabacum) with the dimeric version from the bacterium, Rhodospirillum rubrum, resulted in fully autotrophic and reproductive tobacco plants that required high CO(2) concentrations to grow (Whitney SM, Andrews TJ [2001] Proc Natl Acad Sci USA 98: 14738-14743). Growth and photosynthesis of these plants was compared with that of nontransformed tobacco and other controls where the rbcL gene for the large subunit of tobacco Rubisco was linked to the aadA selectable-marker gene, simulating the gene arrangement of the transformants with R. rubrum Rubisco. An arrangement of the rbcL and aadA genes that gave rise to an abundant monocistronic rbcL transcript and a one-fifth as abundant bicistronic rbcL-aadA transcript had Rubisco levels and photosynthetic properties similar to those of nontransformed tobacco. Direct linkage of the rbcL and aadA genes, resulting in exclusive production of a bicistronic mRNA transcript analogous to that of the transformants with R. rubrum Rubisco, reduced transcript abundance and tobacco Rubisco content. The analogous transcript with the R. rubrum rbcM gene substituted for rbcL was not only reduced in abundance, but was also translated less efficiently. The photosynthetic rates of the transformants and controls were measured at high CO(2) concentrations, using a mass spectrometric method. The rates and their responses to atmospheric CO(2) concentration mirrored the amounts and the kinetic properties of the Rubiscos present. The contents of total nitrogen, carbohydrates, and photosynthetic metabolites of the leaves were also consistent with the content and type of Rubisco.

Carbohydrate Metabolism↗
PubMed1995

A Mirror Furnace for Synchrotron Diffraction Experiments up to 1600K.

An X-ray mirror fumace is described that has been developed for in situ diffraction experiments at a synchrotron source for temperatures up to 1600 K. It can be used in a reducing as well as in an oxidizing atmosphere. In this kind of furnace, the sample is located at one focus of a rotational ellipsoid and heated by the radiation of a halogen lamp located at the other focus. The furnace has been designed to work on a four-circle diffractometer with minimum restriction of the setting angles.

Journal Article↗
PubMed1998

Comparison of monochromators with a bent parabolic mirror and a varied-spacing grating for the 2.0 GeV high-brilliance synchrotron radiation source (VSX).

A design study of monochromators for a 2.0 GeV electron/positron storage ring for high-brilliance synchrotron radiation in the vacuum ultraviolet (VUV) and the soft X-ray regions is described. Two types of VUV/soft X-ray grazing-incidence monochromators, one with a bent parabolic mirror and the other with a varied-spacing grating, are designed. Without any slope error, the expected resolving power of the former is much higher, but the latter is less affected by slope errors of the optical elements.

Journal Article↗
PubMed1998

Design and fabrication of highly heat-resistant Mo/Si multilayer soft X-ray mirrors with interleaved barrier layers.

Introducing interleaved carbon barrier layers improves the heat-resistance of Mo/Si multilayers. The soft X-ray reflectivities of the multilayers were calculated, and the effects of heating on both the reflectivities and layer structures of Mo/Si multilayers with and without barrier layers were investigated using X-ray diffraction and transmission electron microscopy. The results show that, for applications using intense soft X-ray beams, Mo/Si multilayers with interleaved carbon barrier layers are better mirrors than Mo/Si multilayers because they have much better heat resistance and almost the same soft X-ray reflectivity as the Mo/Si multilayers.

Journal Article↗
PubMed2000

Resonant mirror biosensor analysis of type Ialpha cAMP-dependent protein kinase B domain--cyclic nucleotide interactions.

A resonant mirror biosensor was used to study cyclic nucleotide-receptor interactions. In particular, a novel method was developed to determine inhibition constants (Ki) from initial rates of ligate association to immobilized ligand. This approach was applied to the comparison of cyclic nucleotide-binding properties of the wild-type isolated B domain of the cAMP-dependent protein kinase type Ialpha regulatory subunit and its Ala-334-Thr (A334T) variant that has altered cyclic nucleotide specificity. A cUMP-saturated form of the B domain was used for all measurements. Under the conditions used, cUMP did not affect the kinetics of B domain association to immobilized cAMP. Triton X-100 was required to stabilize the protein at nanomolar concentrations. The association and dissociation rate constants for wild-type and A334T B domains yielded equilibrium dissociation constants of 11 and 16 nM. Heterogeneity of ligate and immobilized ligand, mass transport effects, and other factors were evaluated for their influence on biosensor-determined kinetic constants. Biosensor-determined relative inhibition constants (Ki' = Ki(cAMP)/Ki(analog)) for 16 cyclic nucleotide analogs correlated well with those determined by a [3H]cAMP binding assay. Previously published Ki' values for the B domain in the intact regulatory subunit were similar to those of the isolated B domain. The Ki' values for the wild-type and A334T B domains were essentially unchanged except for dramatic enhancements in affinity of cGMP analogs for the A334T B domain. These observations validate the isolated B domain as a simple model system for studying cyclic nucleotide-receptor interactions.

Amino Acid Substitution↗
PubMedDate not supplied

Who's in the mirror? Self-other discrimination in specular images by four- and nine-month-old infants.

This research investigated the early determinants of self-other discrimination in infancy. Ninety-six 4- and 9-month-old infants were placed facing a live image either of themselves or of another person (experimenter) mimicking them. The specular image was either contingent (on-line), or contingent with a 2-s delay. After a first 1-min presentation, the video image of either the self or the other was suddenly frozen for 1 min (still-face episode). This was followed by a last minute of live presentation. From 4 months of age, infants appeared to perceive and act differentially when facing the specular image of themselves or the mimicking other. In general, infants tended to smile more, look more, and have more protracted first-look duration toward the mimicking other compared with the self. Developmentally, 9-month-olds showed markedly more social initiatives toward the mimicking other compared with the self during the still-face episode. In all, these results indicate that infants develop self-other discrimination in specular images long before mirror self-recognition, which is typically reported by the second year. Discrimination of the self from other is interpreted as a precursory ability and a perceptual foundation of later conceptual self development.

Attention↗
PubMed1997

Dental mirror for difficult nasotracheal intubation.

A patient with a previous surgical history of a cleft lip and palate repair and a pharyngeal flap pharyngoplasty was admitted for repair of mandibular prognathism. Following induction of anaesthesia, it was impossible to advance the nasotracheal tube into the oropharynx. Using a dental mirror and retrograde tracheal intubation equipment, under direct vision, the nasotracheal tube was finally advanced into the oropharynx.

Adult↗
PubMed1981

Continuous recording of microvascular dimensions with a rotating mirror microscope.

A system which permits continuous recording of the dimensions of microscopic blood vessels is described. The system uses a combination of a rotating mirror and a pinhole aperture with a microscope to scan microvessel image signals at a rate of one per second. Image signals from the gate circuit are converted to digital signals; further conversion to analogue signals is obtained by integrating the digital signals. The analogue voltages are proportional to the vessel dimensions. A linear relationship was observed over a range of 20-200 micrometer (standard deviation +/- 3.0%). The contrast between vessels and surrounding tissue is amplified by using a B-12 optical filter. By using this system, the mesenteric arteriole was observed after reaction with adrenaline and noradrenaline in rats. The contractile response of the arteriole to adrenaline was greater than with noradrenaline. A maximum response of 20% decrease of the vessel outer diameter is induced by 5.5 x 10(-7) mmol adrenaline and 5.9 x 10(-6) mmol noradrenaline.

Animals↗
PubMed1992

Low-energy electron microscopy (LEEM) and mirror electron microscopy (MEM) of biological specimens: preliminary results with a novel beam separating system.

Low-energy electron microscopy (LEEM) and mirror electron microscopy (MEM) utilize a parallel beam of slow-moving electrons backscattered from the specimen surface to form an image. If the electrons strike the surface an LEEM image is produced and if they are turned back just before reaching the surface an MEM image results. The applications thus far have been in surface physics. In the present study, applications of LEEM and MEM in the biological sciences are discussed. The preliminary results demonstrate the feasibility of forming images of uncoated cultured cells and cellular components using electrons in the threshold region (i.e. 0-10 V). The results also constitute a successful test of a novel beam-separating system for LEEM and MEM.

Animals↗
PubMedDate not supplied

Mirror self-recognition beyond the face.

Three studies (N=144) investigated how toddlers aged 18 and 24 months pass the surprise-mark test of self-recognition. In Study 1, toddlers were surreptitiously marked in successive conditions on their legs and faces with stickers visible only in a mirror. Rates of sticker touching did not differ significantly between conditions. In Study 2, toddlers failed to touch a sticker on their legs that had been disguised before being marked. In Study 3, having been given 30-s exposure to their disguised legs before testing, toddlers touched the stickers on their legs and faces at equivalent levels. These results suggest that toddlers pass the mark test based on expectations about what they look like, expectations that are not restricted to the face.

Awareness↗
PubMed1980

The development of independent secondary ("mirror") discharges in the monkey: failure to replicate earlier findings.

Various factors that might influence the development of the independent secondary focus ("mirror" focus) in the monkey were investigated. Not 1 of 29 monkeys developed independent secondary discharges when we varied: area and length of boundary of the primary epileptogenic agent; ease of passage of agent through pia; nature of chemical agent; mechanical manipulation of homotopic cortex; or site of application of primary agent. The possible reasons for the discrepancy between this negative outcome and our earlier success in obtaining independent foci are discussed.

Aluminum Hydroxide↗
PubMedDate not supplied

Mirror focus: function of seizure frequency and influence on outcome after surgery.

The concept of the mirror focus (MF) implies that an actively discharging epileptiform region may induce similar paroxysmal behavior in a homologous site. In a group of patients with complex partial seizures (CPS) we investigated whether occurrence of a MF was influenced by certain clinical factors and whether surgical outcome was influenced by the presence of an MF. Factors studied included age at onset, duration, and total number of seizures. Patients had had CPS for > 3 years and had pathologically proven temporal lobe neoplasms. Seizure frequency was estimated by the history-taking physician. We estimated total seizure number by multiplying frequency by duration. Seven patients had MF, and 15 did not. Mean age at onset of seizures, duration of seizure disorder, and total seizure number did not vary statistically between the two groups of patients. All patients with an MF except 1 were seizure-free at follow-up. Ten of the 15 patients without MF were seizure-free. Three patients who were not seizure-free had had subtotal resection owing to tumor overlap with eloquent cortex. We conclude that an MF is not a contraindication to operation even when the preponderance of interictal spike activity is contralateral to the tumor or when seizures appear to arise from the MF on scalp EEG.

Adolescent↗
PubMed1992

The oral mucosa as a mirror of general health or disease.

There is a close relationship between general health/disease and oral mucosal reactions. Many diseases show unspecific or specific changes which may evolve throughout the course of the disease but the mucosal reaction may also constitute the initial clinical sign of the disease. Among the broad spectrum of conditions/diseases, three have been selected for this review--HIV/AIDS, Sjögren's syndrome and lichen planus. They illustrate how general disease may be mirrored in the oral mucosa. An attempt has been made to describe the scientific frontiers and to select pertinent key or review articles or books from among the huge amount of literature published in recent years.

Disease↗
PubMed1998

The role of unrecognized ambivalence: the mirroring of family conflicts within the professional and legal network.

This paper raises some questions about the deleterious effects of unrecognized (unconscious) ambivalence running through child care systems, the Children Act and the adversarial legal system. It is postulated that unrecognized ambivalence may become one of the powerful unconscious dynamics contributing to the mirroring of the family conflicts within the professional network. A detailed clinical example, in which we acted as expert witnesses within a child psychiatry hospital team, is used to illustrate how the denial of ambivalence in a highly complex case, that of a large family involved in care proceedings, led to a state of polarization between the family and a team of professionals which was replicated and amplified within the wider welfare and legal system. It is our view that a state of polarization is likely to produce 'all or nothing decisions' which may not be in the best interest of both children and parents. It is argued that the adversarial nature of the legal process and some underlying assumptions in the Children Act, may contribute to ambivalence being unrecognized. Then it is suggested that ambivalence is inevitable both for professionals and families, particularly in highly complex cases, but with its recognition, a resolution may take place. The conclusions contain some suggestions to promote this process.

Adult↗
PubMed1998

Mirror-image artifact can affect transcranial Doppler interpretation.

Transcranial Doppler ultrasonography (TCD) allows evaluation of blood-flow velocity in intracranial arteries detection and monitoring of vasospasm in patients with subarachnoid hemorrhage. Spectral Doppler artifacts can affect TCD data. A 1-month series of TCD findings showed marked fluctuation in blood-flow velocity values in both the middle and anterior cerebral arteries of a patient with subarachnoid hemorrhage. A mirror-image artifact of the Doppler fast Fourier transform velocity spectrum resulted in erroneous interpretation of higher flow velocity in certain vessels. This artifact may cause misinterpretation of TCD flow-velocity data and lead to improper diagnosis of the condition and treatment of patients.

Aneurysm, Ruptured↗
PubMed1990

Mirror movements studied in a patient with Klippel-Feil syndrome.

1. Electromyographic (EMG) recordings have been made from upper limb muscles in a patient with well-defined congenital mirror movements occurring in association with Klippel-Feil syndrome and the results compared to those obtained in normal control subjects. 2. In the patient, liminal percutaneous electrical or magnetic brain stimulation applied over either hemisphere elicited bilateral and symmetrical short-latency muscle responses in relaxed intrinsic hand muscles. In the normal subjects unilateral brain stimulation only elicited contralateral muscle responses. 3. F response and H reflex studies for the patient's ulnar-supplied intrinsic hand muscles were normal. No crossed responses were recorded in the homologous muscles of the contralateral hand. 4. Scalp-recorded somatosensory-evoked responses following ulnar or median nerve stimulation were of normal latency and distribution in the patient. 5. In the patient, cross-correlation analysis of on-going single and multiunit needle EMGs recorded between muscles of left and right hands revealed a central peak in the cross-correlogram. No cross-correlogram peaks were found between left- and right-hand muscles in normal subjects. The magnitude and time course of the central peaks in the cross-correlograms constructed between the firing of motor units on opposite sides of the body in the patient were similar to those found in cross-correlograms constructed between the firing of motor units from muscles on the same side of the body in the patient and in normal subjects. 6. The magnitude of cross-correlogram peaks detected within a muscle and those detected between left and right homologous muscles showed a gradient in which the largest peaks were found in the intrinsic hand and forearm extensor muscles. The smallest peaks were observed in the forearm flexor muscles. No peaks were detected between left and right biceps brachii muscles. In intrinsic hand muscles, the size of the cross-correlogram peak detected between the EMGs of homologous muscle pairs was greater than that found for non-homologous muscle pairs. 7. Cutaneous reflex responses were recorded from first dorsal interosseous muscle following unilateral electrical stimulation of the digital nerves of the index finger. In the patient, this produced an early excitatory (E1) response on the stimulated side. Later excitatory (E2 and E3) responses, of approximately equal size and latency, were distributed bilaterally. In the normal subjects, reflex responses were confined to the stimulated side.(ABSTRACT TRUNCATED AT 400 WORDS)

Arm↗