bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiscale dynamics in communities of phase oscillators
Authors: Anderson Dustin , Tenzer Ari , Barlev Gilad , Girvan Michelle , Antonsen Thomas M. , Ott Edward
Published: January 2012

We investigate the dynamics of systems of many coupled phase oscillators with heterogeneous frequencies. We suppose that the oscillators occur in M groups. Each oscillator is connected to other oscillators in its group with “attractive” coupling, such that the coupling promotes synchronization within the group. The coupling between oscillators in different groups is “repulsive,” i.e., their oscillation phases repel. To address this problem, we reduce the governing equations to a lower-dimensional form via the ansatz of Ott and Antonsen, Chaos 18, 037113 (2008). We first consider the symmetric case where all group parameters are the same, and the attractive and repulsive coupling are also the same for each of the M groups. We find a manifold L of neutrally stable equilibria, and we show that all other equilibria are unstable. For M ≥ 3, L has dimension M − 2, and for M = 2, it has dimension 1. To address the general asymmetric case, we then introduce small deviations from symmetry in the group and coupling parameters. Doing a slow/fast timescale analysis, we obtain slow time evolution equations for the motion of the M groups on the manifold L. We use these equations to study the dynamics of the groups and compare the results with numerical simulations.
Tuning the polarization and magnetism in BiCoO3 by strain and oxygen vacancy effect: A first-principle study
Authors: Chen Xing-Yuan , Chen Li-Juan , Yang Xiao-Bao , Zhao Yu-Jun , Ding Hang-Chen , Duan Chun-Gang
Published: January 2012

The tensile strain and oxygen vacancy effects on the electronic and magnetic properties of multiferroic material BiCoO3 have been studied by density functional theory + U calculations. It is found that the oxygen vacancy at the top of the pyramid structure along the 〈001〉 direction (denoted as O1) can be stabilized at 1+ and 2+ charge states, which significantly changes the local magnetic moment of Co ions and possibly provides net magnetic moments to the BiCoO3 system. While the tensile strain degrades the polarization of BiCoO3 about 20 μC/cm2, the formation of oxygen vacancies becomes easier as the strain increases up to 5%. It indicates that the polarization and magnetic property of BiCoO3 could be tuned by the strain and oxygen vacancies, though the polarization of BiCoO3 is slightly degraded by the oxygen vacancies. Meanwhile, the change of electronic structure and magnetic property introduced by oxygen vacancy is illustrated according to the crystal field theory.
Oxygen and nitrogen plasma hydrophilization and hydrophobic recovery of polymers
Authors: Jokinen Ville , Suvanto Pia , Franssila Sami
Published: January 2012

Plasma hydrophilization and subsequent hydrophobic recovery are studied for ten different polymers of microfabrication interest: polydimethylsiloxane (PDMS), polymethylmethacrylate, polycarbonate, polyethylene, polypropylene, polystyrene, epoxy polymer SU-8, hybrid polymer ORMOCOMP, polycaprolactone, and polycaprolactone/D,L-lactide (P(CL/DLLA)). All polymers are treated identically with oxygen and nitrogen plasmas, in order to make comparisons between polymers as easy as possible. The primary measured parameter is the contact angle, which was measured on all polymers for more than 100 days in order to determine the kinetics of the hydrophobic recovery for both dry stored and rewashed samples. Clear differences and trends are observed both between different polymers and between different plasma parameters.
Imaging spin properties using spatially varying magnetic fields
Authors: Bhallamudi V. P. , Berger A. J. , Labanowski D. E. , Stroud D. , Hammel P. C.
Published: January 2012

We propose a novel method to image spin properties of spintronic systems using the spatially confined field of a scanned micromagnetic probe in conjunction with existing electrical or optical global spin detection schemes. It is thus applicable to all material systems susceptible to either of those approaches. The proposed technique relies on numerical solutions of the spin diffusion equation in the presence of spatially varying fields to obtain the local spin response to a micromagnetic probe field.
Super-resolution spatial frequency differentiation of nanoscale particles with a vibrating nanograting
Authors: Alekseyev Leonid , Narimanov Evgenii , Khurgin Jacob
Published: January 2012

We propose a scheme for detecting and differentiating deeply subwavelength particles based on their spatial features. Our approach combines scattering from an ultrasonically modulated nanopatterned grating with heterodyne techniques to enable far-field detection of high spatial frequency Fourier components. Our system is sensitive to spatial features commensurate in size to the patterning scale of the grating. We solve the scattering problem in Born approximation and illustrate the dependence of the signal amplitude at modulation frequency on grating period, which allows to differentiate between model nanoparticles of size λ/20.
Development of revolving drop surface tensiometer
Authors: Mitani S. , Sakai K.
Published: January 2012

A revolving drop surface tensiometer, which measures the surface tension of a small amount of liquid, is proposed. A remarkable feature of this device is that while using the pendant drop method, it employs a centrifugal force to deform the liquid droplet. The centrifugal force induces a large distortion of the droplet, which enables an accurate measurement of the surface tension to be made. In our experimental setup, the centrifugal force can be increased so that the apparent acceleration becomes up to 100 times larger than that due to gravity, and the capability of this method to measure surface tensions was demonstrated with ethylene glycol.
Modulation of surface plasmon wave by photo-induced refractive index changes of CdSe quantum dots
Authors: Chen Horng-Shyang , Wang Jyh-Yang , Yeh Sheng-Shiuan , Chen Chii-Dong , Lin Hung-Yi
Published: January 2012

We demonstrate an all-optical modulation of surface plasmon resonance by photo-irradiation induced dielectric constant change of CdSe quantum dots on the gold surface. The dipole-dipole interaction between the surface plasmon and the photo-induced excitons in the dots gives rise to a shift in the surface plasmon resonance peak. This shift is found to sensitively reflect a tiny change in the dielectric constant, which is useful for investigating the nonlinear effect in active plasmonic components.
Nanostructured barbed wire architecturing of organic conducting material blends by electrospinning
Authors: Mishra Sumeet R. , Ranjith K. , Swathi S. K. , Ramamurthy Praveen C.
Published: January 2012

In this study, fibers of barbed wire structure were obtained by electrospinning blend of organic conducting crystalline material and polyethylene oxide. Thermal and structural characterization of the blend fibers has been carried out to study the fiber characteristics. An increase in crystallinity in the electrospun fibers was observed and was attributed to both electrospinning process as well as addition of organic conducting crystalline material. A mechanism for the formation of this barbed wire structure has also been proposed.
Insulated gold scanning tunneling microscopy probes for recognition tunneling in an aqueous environment
Authors: Tuchband Michael , He Jin , Huang Shuo , Lindsay Stuart
Published: January 2012

Chemically functionalized probes are required for tunneling measurements made via chemical contacts (“Recognition Tunneling”). Here, we describe the etching of gold STM probes suitable for chemical functionalization with moieties bearing thiol groups. Insulated with high density polyethylene, these probes may be used in aqueous electrolytes with sub pA leakage currents. The area of the exposed probe surface was characterized via the saturation current in an electroactive solution (0.1 M K3Fe(CN)6). Twenty five percent of the probes had an exposed region of 10 nm radius or less.
Electrical transport through heterojunctions of single-walled carbon/silicon carbide/carbon nanotubes
Authors: Jia Jianming , Ju Shin-Pon , Shi Daning , Lin Kuan-Fu
Published: January 2012

The transport properties of heterojunctions composed of SiC nanotubes (SiCNTs) with different length coupled between metallic carbon nanotubes (CNTs) have been investigated using a combined density-functional theory and nonequilibrium Green’s function formalism. It is shown that the conductance of heterojunction decreases exponentially with the increasing length of SiCNT. The current-voltage curve of the system is linear for short SiCNT, but becomes gradually nonlinear for longer SiCNT, indicating a transition from metallic characteristics to semiconductor-like behavior. The observed trends can be understood by the electron tunneling between metallic CNTs. The present results provide insights into the physical mechanism of heterojunctions and are useful for their applications in electronic devices.
Perfect spin-filter and highly spin-polarized current in a quantum network device
Authors: Fu Hua-Hua , Yao Kai-Lun
Published: January 2012

We report a design to realize perfect spin-filter and highly spin-polarized current in a quantum network device composed of multiple quantum dots (QDs). By producing an energy difference between the site energy of the upper QDs and down ones, the linear conductance spectra present well-defined insulating bands with very steep edges due to the Fano antiresonance in some suitable conditions. Considering a Zeeman splitting, highly to 100% spin-polarized windows appear in the conductance spectra, which makes the network device can be used as a perfect spin filter to generate completely spin-polarized current. This idea opens a practical way to prompt other similar configures of the network to realize perfect spin-filter.
First-principles study of pressure-induced phase transition and electronic property of PbCrO3
Authors: Wang Bao-Tian , Yin Wen , Li Wei-Dong , Wang Fangwei
Published: January 2012

We have performed a systematic first-principles investigation to calculate the structural, electronic, and magnetic properties of PbCrO3, CrPbO3 as well as their equiproportional combination. The local density approximation (LDA) + U and the generalized gradient approximation + U theoretical formalisms have been used to account for the strong on-site Coulomb repulsion among the localized Cr 3d electrons. By choosing the Hubbard U parameter around 4 eV within LDA + U approach, ferromagnetic, and/or antiferromagnetic ground states can be achieved and our calculated volumes, bulk moduli, and equation of states for PCO-CPO in R3 phase and PCO in Pm3¯m or R3c phases are in good agreement with recent experimental Phase I and Phase II [W. Xiao etal., PNAS 107, 14026 (2010)], respectively. Under pressure, phase transitions of R3 PCO-CPO to Pm3¯m PCO at 1.5 GPa and R3 PCO-CPO to R3c PCO at −6.7 GPa have been predicted. The abnormally large volume and compressibility of Phase I are due to the content of CrPbO3 in the experimental sample and the transition of PbO6/2 octahedron to CrO6/2 upon compression. Our electronic structure study showed that there will occur an insulator-metal transition upon the phase transitions. Clear hybridization of Cr 3d and O 2p orbitals in wide energy range has been observed.
Beam broadening of polar molecules and clusters in deflection experiments
Authors: Bulthuis J. , Kresin V. V.
Published: January 2012

A beam of rotating dipolar particles (molecules or clusters) will broaden when passed through an electric or magnetic field gradient region. This broadening, which is a common experimental observable, can be expressed in terms of the variance of the distribution of the resulting polarization orientation (the direction cosine). Here, the broadening for symmetric-top and linear rotors is discussed. These two types of rotors have qualitatively different low-field orientation distribution functions, but behave similarly in a strong field. While analytical expressions for the polarization variance can be derived from first-order perturbation theory, for experimental guidance it is important to identify the applicability and limitations of these expressions, and the general dependence of the broadening on the experimental parameters. For this purpose, the analytical results are compared with the full diagonalization of the rotational Stark-effect matrices. Conveniently for experimental estimations, it is found that for symmetric tops, the dependence of the broadening parameter on the rotational constant, the axial ratio, and the field strength remains similar to the analytical expression even outside of the perturbative regime. Also, it is observed that the shape envelope, the centroid, and the width of the orientation distribution function for a symmetric top are quite insensitive to the value of its rotational constant (except at low rotational temperatures).
Enhanced upconversion fluorescence of Er3+:ZrO2 nanocrystals induced by phase transformation
Authors: Liu L. , Chen Y. J. , Zhang X. L. , Wang Y. X. , Zhang X. R. , Song Y. L.
Published: January 2012

In this letter, we demonstrate for the first time a growth of monoclinic phase ZrO2 nanocrytals based on a sol-gel method, compared to the ordinary sol-gel procedure, our method decreases the synthesized temperature from ∼1000 °C to ∼800 °C. In addition, it is found that Er3+ in monoclinic phase ZrO2 nanocrystals have greatly enhanced upconversion emissions under infrared LD excitation due to its lower environmental symmetry.
Recent developments in US patent law
Authors: Boucher Patrick M.
Published: January 2012

Legislation making the US the last country to abandon the first-to-invent patent system should have a significant effect on the way scientists approach patenting.
Estrogen receptor-α expression in neuronal cells affects bone mass
Authors: Ohlsson Claes , Engdahl Cecilia , Börjesson Anna E. , Windahl Sara H. , Studer Erik , Westberg Lars , Eriksson Elias , Koskela Antti , Tuukkanen Juha , Krust Andree , Chambon Pierre , Carlsten Hans , Lagerquist Marie K.
Published: January 2012

It has generally been assumed that bone mass is controlled by endocrine mechanisms and the local bone environment. Recent findings demonstrate that central pathways are involved in the regulation of bone mass. Estrogen is involved in the regulation of bone homeostasis and the CNS is also a target for estrogen actions. The aim of this study was to investigate in vivo the role of central estrogen receptor-α (ERα) expression for bone mass. Nestin-Cre mice were crossed with ERα
flox
mice to generate mice lacking ERα expression specifically in nervous tissue (nestin-ERα
−/−
). Bone mineral density was increased in both the trabecular and cortical bone compartments in nestin-ERα
−/−
mice compared with controls. Femoral bone strength was increased in nestin-ERα
−/−
mice, as demonstrated by increased stiffness and maximal load of failure. The high bone mass phenotype in nestin-ERα
−/−
mice was mainly caused by increased bone formation. Serum leptin levels were elevated as a result of increased leptin expression in white adipose tissue (WAT) and slightly increased amount of WAT in nestin-ERα
−/−
mice. Leptin receptor mRNA levels were reduced in the hypothalamus but not in bone. In conclusion, inactivation of central ERα signaling results in increased bone mass, demonstrating that the balance between peripheral stimulatory and central inhibitory ERα actions is important for the regulation of bone mass. We propose that the increased bone mass in nestin-ERα
−/−
mice is mediated via decreased central leptin sensitivity and thereby increased secretion of leptin from WAT, which, in turn, results in increased peripheral leptin-induced bone formation.
Exploring Strategies for Gizzard Shad Removal That Account for Compensatory Density Dependence and Uncertainty
Authors: Catalano Matthew J. , Allen Micheal S.
Published: January 2012

Gizzard shad Dorosoma cepedianum have been the target of removal efforts in eastern North American lakes due to their omnivorous feeding, which may increase nutrient cycling and contribute to high phytoplankton abundance. We used a simulation model to evaluate the efficacy of a gizzard shad removal program at the Harris Chain of Lakes (HCL), Florida, by testing the effects of the exploitation rate, gill-net mesh size, and harvest interval on the total population biomass and spawning potential ratio (SPR). The analysis accounted for compensatory density dependence of the gizzard shad population and uncertainty in life history parameters. The reductions in gizzard shad biomass and SPR were less than 50% for the two largest mesh sizes (89 and 102 mm) at realistic annual exploitation rates of 0.6–0.8. However, the use of smaller mesh sizes (51 and 64 mm) produced biomass and SPR reductions that exceeded 75% at comparable harvest rates. Current removal efforts at the HCL, which employ a minimum gill-net mesh size of 102 mm, are unlikely to reduce gizzard shad biomass substantially. However, smaller mesh sizes could result in increased bycatch of economically important black crappies Pomoxis nigromaculatus. Our study sheds light on the importance of using simulation models to forecast the effects of removal efforts on target fish species. The results of such models can be used to inform harvest practices to achieve desired outcomes.

Received May 12, 2011; accepted September 12, 2011
Three-dimensional flow measurements induced from serpentine plasma actuators in quiescent air
Authors: Durscher R J , Roy S
Published: January 2012

This paper presents three-dimensional flow measurements performed on a dielectric barrier discharge (DBD) actuator with the electrodes in a serpentine design. Such a configuration induces a local pinching and a local spreading of the fluid as one follows along the span of the actuator. In this work two different variations on the serpentine configuration are evaluated: one constructed from patterned circular arcs and one from patterned rectangles. The influence of applied voltage is studied for the former case. To quantify these effects stereo particle image velocimetry (PIV) is used to generate time averaged, spatially resolved measurements of the detailed flow structure. The three components of the velocity vector are measured along spanwise and streamwise cuts. These slices are then reconstructed to provide a three-dimensional view of the induced flow field. The results for the induced flow fields are also compared with stereo-PIV measurements made on a standard linear DBD actuator. A truly three-dimensional induced flow field was observed as a result of the serpentine configuration. These designs could be beneficial for rapid mixing of the local fluid.
Luminescence at 1.5 µm from Si/GeSn nanodot/Si structures
Authors: Nakamura Yoshiaki , Fujinoki Norihito , Ichikawa Masakazu
Published: January 2012

Broad photoluminescence (PL) around 1.5 µm (∼0.8 eV) from Si/GeSn nanodot (ND)/Si structures was enhanced by high temperature post-annealing. This PL was related to radiative electronic states created in the Si-capping layer owing to the underlying GeSn NDs. A light-emitting diode was fabricated containing the Si-capped GeSn NDs as an active layer. Broad electroluminescence (EL) was observed even at room temperature (RT) near 0.8 eV which is consistent with the optical fibre communication wavelength (∼1.5 µm). The temperature dependence of the integrated EL intensity revealed two activation energies of 3 and 33 meV. The light emission with a higher activation energy of 33 meV leading to the RT luminescence was considered to have the same origin as that of broad PL. This demonstrates that the Si/GeSn ND/Si structures are promising as a group IV-based light-emitting material compatible with Si technology.
Seasonal variation in the egg morphology of the copepod Eurytemora americana and its relationship with reproductive strategy in a temperate estuary in Argentina
Authors: Berasategui Anabela A. , Hoffmeyer Mónica S. , Dutto M. Sofía , Biancalana Florencia
Published: January 2012

Berasategui, A. A., Hoffmeyer, M. S., Dutto, M. S., and Biancalana, F. 2012. Seasonal variation in the egg morphology of the copepod Eurytemora americana and its relationship with reproductive strategy in a temperate estuary in Argentina. – ICES Journal of Marine Science, 69: 380–388. Seasonal variation in the morphology of Eurytemora americana eggs and its relationship with reproductive strategy were studied in the Bahía Blanca Estuary. Eggs from field females were analysed morphologically by optical (OM) and electron microscopy [scanning electron microscopy (SEM)–transmission electron microscopy (TEM)] during the population pulse. Additionally, egg-carrying females were incubated simulating in situ environmental conditions to evaluate the resting egg character. Subitaneous and resting eggs were indistinguishable by OM, but showed different chorion appearance under SEM and TEM. Sinuous patterned chorion eggs, mainly produced during the period of population growth, were classed as subitaneous eggs based on their high level of hatching success. Eggs with a sponge-like appearance, produced after the population peaked, were classed as diapause eggs based on their inability to hatch even under favourable conditions. There were significant differences in egg size through the population pulse and diapause eggs were significantly bigger than subitaneous eggs. The observation of both morphotypes in egg-carrying females after peak population abundance confirms the existence of a transitional reproductive stage before the exclusive production of diapause eggs at the end of the pulse. Diapause egg production enables E. americana to resist adverse conditions, ensuring its survival in temperate estuaries.
On being a patient
Authors: Booth Christopher
Published: January 2012

Those who practise medicine should remember that we are all patients at some time, but particularly at the beginning and end of our lives. Even distinguished professors and historians of medicine are not spared, as this account reveals. Doctors and those who manage and organize health services must recognize that patients may find it difficult to access care when they need it; that rapid relief of pain, by whatever means is appropriate, is absolutely crucial; that patients are often faced by a bewildering number of staff, who rotate on and off duty, and continuity of care is important—being looked after by a doctor or nurse whom you get to know and who understands your illness is essential for morale; that apparently simple procedures such as venesection or urinary catheterization require explanation, since they may cause great distress; that despondency mounts when there is unaccountable delay in carrying out scheduled procedures. Practical and important though many procedures are, requiring both skill and experience, for the patient, nothing can replace the compassion and sympathy that the caring professions owe the afflicted. So many aspects of excellent practice stem from these simple human qualities, which thankfully survive despite the strong business ethic that pervades medicine in many countries today. One other lesson remains. If you are a physician, no matter how important you may think you are, you should, so far as your own illnesses are concerned, consider yourself a layman....
Large-scale randomized evidence: trials and meta-analyses of trials
Authors: Baigent C. , Peto R. , Gray R. , Parish S. , Collins R.
Published: January 2012

As long as doctors start with a healthy scepticism about the many apparently striking claims and counter-claims that appear in the medical literature, trial results do make sense. The main enemy of common sense is over-optimism: there are a few striking exceptions where treatments for serious disease work extremely well, but many claims of vast improvements from new therapies turn out to be evanescent....
Cytokines
Authors: McInnes Iain B.
Published: January 2012

Cytokines are small glycoprotein mediators that are involved in every facet of immune effector function and regulation. More than 200 cytokines have been identified, which may usefully be classified in structurally related superfamilies. They can (1) function through binding to specific receptors that in turn signal via complex transduction pathways to regulate gene expression, thereby mediating positive and negative regulatory activities; (2) operate as soluble mediators in the extracellular domain or within cells, where they may also traffic to the nucleus and exhibit dual function as transcriptional regulators; (3) be expressed initially on the cell membrane, where they may exert effector function directly in cell–cell interactions, or from which they can be subsequently cleaved to yield bioactive soluble molecules, thereby mediating autocrine and paracrine activities around their cellular source....
Immunodeficiency
Authors: Kumararatne D.
Published: January 2012

Immunodeficiency is caused by failure of a component of the immune system and results in increased susceptibility to infections. The possibility that a patient has an underlying immunodeficiency should be considered in the following circumstances: (1) serious, persistent, unusual or recurrent infections; (2) failure to thrive in infancy; (3) known family history of immunodeficiency; (4) unexplained lymphopenia in infancy; (5) combination of clinical features characteristic of a particular immunodeficiency syndrome. The nature of the microbial infection in a particular patient provides a clue to the likely cause of immunodeficiency....
The genetics of inherited cancers
Authors: Eeles Rosalind A.
Published: January 2012

All cancer can be termed ‘genetic’ as cancer is caused by somatic cell mutations (alterations in the DNA code), which result in abnormal cellular growth and/or proliferation. Most of these mutations are sporadic (only occurring in the cancer cell), but some are due to the inheritance of a germ-line mutation in a cancer predisposition gene....
Sexual behaviour
Authors: Johnson Anne M. , Mercer Catherine H.
Published: January 2012

Discussion of sexual lifestyle and the ability to take a sexual history are relevant to a wide range of clinical practice. Most of the population is attracted to, and has sex, exclusively with people of the opposite sex. The age at which people first have sex has decreased in recent decades, increasing the time available to accumulate sexual partners and thus be at risk of STIs, including HIV. While many people have few partners, a small proportion of the population has many....
Poisoning by drugs and chemicals
Authors: Vale J.A. , Bradberry S.M. , Bateman D.N.
Published: January 2012

Poisoning is usually an acute, short-lived event which necessitates immediate care, though complications such as rhabdomyolysis may persist for a few days. Less commonly, symptoms may arise only after prolonged exposure, as occurs with many heavy metals. Rarely, sequelae may not occur until many years after exposure, e.g. with vinyl chloride. It must be stressed that exposure does not necessarily equate with poisoning as uptake of the agent involved is required but, even if this occurs, poisoning does not necessarily result as the amount absorbed may be too small....
Diving medicine
Authors: Denison D.M. , Glover M.A.
Published: January 2012

Diving remains the principal means of exploring and exploiting shallower underwater zones. Immersion and rapid increase in pressure with depth cause most problems unique to diving.

Gas density, partial pressures, and solubility vary proportionately with ambient pressure. At elevated partial pressure, nitrogen becomes narcotic, as can other inert gases, and contaminants barely detectable at the surface can become toxic as their partial pressures rise with depth. Hyperoxia irritates the lungs and the central nervous system, and sometimes causing generalized seizures. A safe gas mixture at depth can become hypoxic as the partial pressure of oxygen decreases during the return to surface....
Inherited diseases of copper metabolism: Wilson’s disease and Menkes’ disease
Authors: Schilsky Michael L. , Mistry Pramod K.
Published: January 2012

Copper is an essential metal that is an important cofactor for many proteins and enzymes. Two related genetic defects in copper transport have been described.

An uncommon disorder (1 in 30 000) caused by autosomal recessive loss of function mutations in a metal-transporting P-type ATPase (...
Congenital adrenal hyperplasia
Authors: Hughes I.A.
Published: January 2012

Congenital adrenal hyperplasia (CAH) results from enzymatic defects in the pathways of adrenal steroidogenesis, with over 90% of cases being due to 21-hydroxylase deficiency caused by autosomal recessive mutations in the CYP21 gene.

Classical presentation—this is in the neonatal period with ambiguous genitalia/virilization of a female infant, with phenotype traditionally subdivided according to the presence (75%) or absence of salt wasting, which in affected males is the sole manifestation (and can, if unrecognized, be life-threatening). Delayed presentations can occur, manifest in women as hirsutism, oligomenorrhoea, and infertility and in men as infertility or testicular adrenal rest tumours....
Disorders of male reproduction
Authors: Srinivas-Shankar U. , Wu F.C.W.
Published: January 2012

Luteinizing hormone (LH) stimulates biosynthesis of androgenic steroids by binding to specific surface membrane receptors on the Leydig cells in the testis. Testosterone is essential for male sexual differentiation, growth and function of the male genital tract, secondary sexual characteristics, sexual potency, and production of spermatozoa....
Hypertension in pregnancy
Authors: Redman C.W.G.
Published: January 2012

In normal pregnancy the arterial pressure falls in the second half of the first trimester: systolic pressure then remains unchanged throughout pregnancy, with diastolic pressure tending to rise gradually towards its prepregnancy level in the later weeks.

Definitions, epidemiology and clinical features—(1) Pregnancy-induced hypertension (PIH), transient hypertension of pregnancy, or gestational hypertension describe new hypertension, defined as blood pressure equal to or in excess of 140/90 mmHg, which without proteinuria affects up to 10% of women after mid term (20 weeks) and resolves after delivery. (2) Pre-eclampsia, which affects 3 to 5% of pregnancies, is defined by the presence of PIH and pregnancy-induced proteinuria arising after 20 weeks gestation that both improve after delivery. Other features include (a) renal insufficiency; (b) hepatocellular dysfunction and/or severe epigastric/right upper quadrant pain; (c) neurological problems—convulsions (eclampsia), severe headaches, persistent scotomata; (d) haematological disturbances—thrombocytopenia, disseminated intravascular coagulation, haemolysis; (e) fetal growth restriction....
Liver and gastrointestinal diseases in pregnancy
Authors: Gimson Alexander
Published: January 2012

Hyperemesis gravidarum—a condition of unknown cause where severe vomiting can lead to volume depletion, ketonuria, electrolyte disturbances, and nutritional deficiency. Management is supportive.

Intrahepatic cholestasis of pregnancy—a common cause of jaundice in pregnancy, presenting in the second or third trimester, usually with pruritus. Serum bilirubin and aminotransferases may be elevated, with no significant rise in alkaline phosphatase (beyond the normal elevation expected in pregnancy) or ...
Miscellaneous disorders of the bowel and liver
Authors: Gimson Alexander
Published: January 2012

A wide range of miscellaneous disorders can affect the bowel and liver: some that are relatively common and of particular note are:

Microscopic colitis—characterized by the triad of watery diarrhoea, a normal macroscopic colonoscopy, and specific histology showing either a lymphocytic colitis or collagenous colitis. May resolve spontaneously, but treated with budesonide if it does not....
Chronic peripheral oedema and lymphoedema
Authors: Mortimer Peter S.
Published: January 2012

Lymph transport, not venous reabsorption, is the main process responsible for interstitial fluid drainage. All peripheral oedema is either absolute or relative lymph drainage failure. Oedema develops when the microvascular filtration rate exceeds lymph drainage for a sufficient period, either because the filtration rate is high or because lymph flow is low, or a combination of the two. Lymphoedema is strictly peripheral oedema due solely to a failure of lymph drainage. Most peripheral oedema arises from microvascular fluid filtration overwhelming lymph drainage, e.g. heart failure, but lymphoedema supervenes as lymph function declines if high filtration is sustained....
The clinical approach to the patient who is very ill
Authors: Firth John D.
Published: January 2012

When dealing with emergency admissions (and sometimes in other contexts), always ask yourself the question ‘is this patient well, ill, very ill, or nearly dead?’ Airway, breathing, and circulation (ABC) must be assessed immediately in the patient who is very ill or worse, a key further question being ‘do you think that this patient can keep breathing like this for the next 10 min?’ If not, summon help from someone with advanced airway skills immediately....
Management of raised intracranial pressure
Authors: Menon David K.
Published: January 2012

Normal intracranial pressure (ICP) is between 5 and 15 mmHg in supine subjects. Intracranial hypertension (ICP >20 mmHg) is common in many central nervous system diseases and in fatal cases is often the immediate cause of death.

Aetiology and pathogenesis—increases in intracranial volume and hence—given the rigid skull—ICP may be the consequence of (1) brain oedema, (2) increased cerebral blood volume, (3) hydrocephalus, and (4) space-occupying lesions. Brain perfusion depends on the difference between mean arterial pressure and ICP, termed cerebral perfusion pressure (CPP). The normal brain autoregulates cerebral blood flow down to a lower limit of CPP of about 50 mmHg in healthy subjects, and perhaps 60 to 70 mmHg in disease. CPP reduction to below these values results in cerebral ischaemia....
Pulmonary complications of HIV infection
Authors: Rosen Mark J.
Published: January 2012

The lung is a frequent site of opportunistic infection in patients with HIV infection, and noninfectious pulmonary disorders associated with HIV infection and antiretroviral treatments are increasingly common. The severity of immunocompromise, with CD4+ lymphocyte count the most reliable surrogate, is the primary determinant of the risk of developing specific pulmonary disorders: early in the course of HIV these are similar to those seen in the general population; opportunistic infections occur with severe immunodeficiency, but with frequency reduced by prophylaxis....
Diffuse parenchymal lung disease: an introduction
Authors: Wells A.U.
Published: January 2012

Case History—A 42 yr old man with progressively increasing breathlessness and reticular shadowing on his chest radiograph.

The nomenclature of diffuse parenchymal lung disease has caused a great deal of confusion, with use of complicated histopathological terms not always corresponding exactly to clinico-radiological entities....
Lymphocytic infiltrations of the lung
Authors: Hendrick D.J.
Published: January 2012

Case History—A 37 yr old woman with common variable immunodeficiency, now presenting with a 6-week history of breathlessness and productive cough.

Many disorders are associated with lymphocytic infiltration of the lung, but there is a spectrum of conditions in which such infiltration is the chief focus of attention, ranging from benign (e.g. lymphocytic interstitial pneumonia) to malignant (e.g. lymphoma)....
Lipoid (lipid) pneumonia
Authors: Hendrick D.J.
Published: January 2012

Lipids that accumulate within airways and alveolae are difficult to remove and may lead to an inflammatory response. Exogenous lipid can be aspirated in those with impaired swallowing mechanisms who take or are given agents such as olive oil or paraffin, or can be inhaled from oil aerosols/mists. Endogenous lipid can (rarely) be deposited when chronic inflammation accompanies some cause of localized bronchial obstruction. Presentation is with a chronic ‘pneumonic’ illness or asymptomatic radiographic abnormality, when appearances may closely simulate bronchial carcinoma. Demonstration of lipid material within pulmonary secretions or alveolar macrophages obtained from sputum or bronchoalveolar lavage is diagnostic. If treatment is needed, therapeutic bronchoalveolar lavage may remove substantial quantities of lipid from the alveoli; episodes of secondary bacterial infection require antibiotic treatment....
Clinical investigation
Authors: Doherty Michael , Lanyon Peter C.
Published: January 2012

Laboratory and imaging markers are an adjunct to competent clinical assessment and should not be used as a substitute. Tests should only be ordered if the results will alter diagnosis, prognosis, or clinical management.

Synovial fluid examination—this is the key investigation to confirm the diagnosis of either acute crystal or septic arthritis. Fluid can usually be obtained by direct aspiration from any peripheral joint, or alternatively under ultrasound guidance. The identification of crystals requires compensated polarized light microscopy....
Pyogenic arthritis
Authors: Berendt Anthony R.
Published: January 2012

Acute pyogenic arthritis may be primary (by haematogenous spread) or secondary (to trauma, surgery, or arthrocentesis). Organisms that cause primary septic arthritis are usually aggressive pathogens: Staphylococcus aureus (most commonly), streptococci, salmonella species (especially in African children) and Gram-negative organisms (neonates and older people). The causes of secondary and chronic septic arthritis are more diverse, including lower-grade pathogens from skin, mycobacteria, and fungi....
Polymyalgia rheumatica and temporal arteritis
Authors: Tore Gran Jan
Published: January 2012

Polymyalgia rheumatica and temporal arteritis are distinct but overlapping inflammatory conditions of unknown aetiology. They almost exclusively affect people over 50 years of age, women more than men (ratio 2–3:1), and particularly those of Nordic heritage.

Temporal arteritis is characterized by granulomatous inflammation that penetrates all layers of the wall of medium and (often) large muscular arteries, in particular the superficial temporal artery. Histological examination of tissues from patients with polymyalgia rheumatica shows nonspecific changes only. The term ‘giant cell arteritis’ is properly used only to describe patients with biopsy-proven arteritis....
Disorders of water and sodium homeostasis
Authors: Moritz Michael L. , Ayus Juan Carlos
Published: January 2012

Water intake and the excretion of water are tightly regulated processes that are able to maintain a near-constant serum osmolality. Sodium disorders (dysnatraemias—hyponatraemia or hypernatraemia) are almost always due to an imbalance between water intake and water excretion.

Understanding the aetiology of sodium disorders depends on understanding the concept of electrolyte-free water clearance—this is a conceptual amount of water that represents the volume that would need to be subtracted (if electrolyte-free water clearance is positive) or added (if negative) to the measured urinary volume to make the electrolytes contained within the urine have the same tonicity as the plasma electrolytes. It is the concentration of the electrolytes in the urine, not the osmolality of the urine, which ultimately determines the net excretion of water....
Chronic kidney disease
Authors: Ritz Eberhard , Drüeke Tilman B.
Published: January 2012

Definition—chronic kidney disease (CKD) is defined as kidney damage lasting for more than 3 months characterized by structural or functional abnormalities of the kidney, with or without decreased glomerular filtration rate (GFR).

Staging—CKD has been subdivided into five stages depending on the estimated GFR (eGFR), as described in ...
Chronic tubulointerstitial nephritis
Authors: De Broe Marc E. , D’Haese Patrick C. , Elseviers Monique M.
Published: January 2012

Chronic tubulointerstitial nephritis is usually asymptomatic, presenting with slowly progressive renal impairment. Urinalysis may be normal or show low-grade proteinuria (<1.5 g/day) and/or pyuria. Diagnosis depends on renal biopsy, which reveals variable cellular infiltration of the interstitium, tubular atrophy, and fibrosis. There are many causes including sarcoidosis, drugs (prescribed and nonprescribed), irradiation, toxins, and metabolic disorders....
Cell and molecular biology of human leukaemias
Authors: Gutierrez Alejandro , Thomas Look A.
Published: January 2012

The human leukaemias arise when haematopoietic stem and progenitor cells acquire genetic alterations that lead to malignant transformation, following which affected cells can exhibit differentiation arrest in any lineage and at any stage of maturation.

Genetic alterations leading to leukaemia—a recurring theme is that the genes most frequently altered are those with evolutionarily conserved roles in the embryological development of various cell lineages and organ systems, including (but not limited to) genes that control normal haematopoiesis. The molecular genetic alterations that drive leukaemogenesis can generally be characterized into lesions affecting transcription factors and those that aberrantly activate signal transduction pathways, which often occur via activating mutations in tyrosine kinases....
The polycythaemias
Authors: Ciurea Stefan O. , Hoffman Ronald
Published: January 2012

Polycythaemia or erythrocytosis is characterized by an abnormal increase in the numbers of red blood cells, leading to an elevation in the haemoglobin concentration and haematocrit (>52% in men and >48% in women). The cause may be either (1) primary—due to an intrinsic defect of haemopoietic stem cells; or (2) secondary—due to extrinsic stimulation of progenitor erythroid cells by circulating growth factors; and the condition needs to be distinguished from (3) pseudopolycythaemia—in which haematocrit is raised because the plasma volume is decreased....
Normochromic, normocytic anaemia
Authors: Weatherall D.J.
Published: January 2012

A mild normochromic, normocytic anaemia is a common finding and usually a consequence of other diseases, including (1) anaemia of chronic disorders—associated with chronic infection, all forms of inflammatory diseases, and malignant disease; mechanism unknown but likely to involve multiple factors; typically leads to a reduction in the serum iron concentration with concurrent reduction in the level of transferrin, hence saturation of the iron binding capacity is usually normal or only slightly reduced; (2) other disorders—including renal failure, hypothyroidism, hypopituitarism, marrow failure (aplastic anaemia, infiltration, pure red-cell aplasia), acute blood loss, and polymyalgia rheumatica. Treatment is that of the underlying condition, with a therapeutic trial of corticosteroids justified—after exclusion of underlying blood dyscrasias and paraproteinaemias—in elderly patients with anaemia in association with a very high sedimentation rate....
Vesiculobullous disease
Authors: Wojnarowska Fenella
Published: January 2012

The autoimmune blistering diseases have a dramatic clinical presentation, and are significant diseases with substantial morbidity and mortality.

The diseases can be split broadly pathologically into intraepidermal (pemphigus) and subepidermal (pemphigoid, dermatitis herpetiformis and others) groups, the former being characterized by pathogenic autoantibodies to desmosome components, and the latter by pathogenic antibodies to proteins of the basement membrane zone adhesion complex that link the epithelium/epidermis to the underlying mesenchyme/dermis (or genetic mutations of the same proteins). There are concomitant differences in clinical presentation, e.g. blistering lesions present in the subepidermal bullous diseases tend to be less easily ruptured than those observed in intraepidermal bullous diseases....
Introduction and approach to the patient with neurological disease
Authors: Compston Alastair
Published: January 2012

Clinical neurology uses conversation, detailed questioning and discussion, observation, structured examination, and selective investigation to formulate problems into an anatomical and pathological framework. The competent neurologist senses and probes relevant components of the history, reliably elicits the physical signs, knows which investigations are necessary and relevant, appreciates the most likely underlying diagnosis and mechanism of disease, and communicates relevant information to the patient accurately, intelligibly, and sensitively. This system has evolved over several centuries, during which much knowledge has accumulated on structure and function in health and disease, the reliability of physical signs and laboratory investigations, and the nosology of disease....
The human genome sequence
Authors: Brenner Sydney
Published: January 2012

The ability to clone and propagate fragments of DNA, along with technical advances that allow the order of nucleotide bases to be determined, has led to sequencing of the entire human genome. It may be that ultimately this information will lead to the uncovering of numerous targets for therapeutic purposes, but much additional biological and clinical research will be required on gene and protein function in living cells, whole organisms and people....
A male-killing
Wolbachia
carries a feminizing factor and is associated with degradation of the sex-determining system of its host
Authors: Sugimoto Takafumi N. , Ishikawa Yukio
Published: January 2012

Endosymbiotic bacteria of the genus
Wolbachia
induce diverse reproductive alterations in their insect hosts.
Wolbachia
(wSca) infecting the moth
Ostrinia scapulalis
causes unusual male killing, in which males (genotype: ZZ) selectively die during embryonic and larval development, whereas females (genotype: ZW), in turn, selectively die when cured of infection. To gain insight into the interaction between wSca and the host, we analysed phenotypic and genetic sexes of the embryos and larvae of normal, wSca-infected, and infected-and-cured
O. scapulalis
by diagnosing the sex-specifically spliced transcripts of
Osdsx
—a homologue of the sex-determining gene
doublesex
—and sex chromatin in interphase nuclei, respectively. It was observed that the female-type
Osdsx
was expressed in the infected male (ZZ) progenies destined to die, whereas the male-type
Osdsx
was expressed in the cured female (ZW) progenies destined to die. These findings suggest that (i) wSca, a male killer, carries a genetic factor that feminizes the male host, (ii) the sex-determining system of the host is degraded, and (iii) a mismatch between the genetic and phenotypic sexes underlies the sex-specific death.