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Biomedical subjects

D Hofman

Publications and source records attributed to D Hofman.

At least 19 recordsLinked to original sources
PubMed2002

Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV.

This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0<eta<5.3) for the first time at this energy. The result, averaged over momenta and particle species, is observed to reach 7% for peripheral collisions at midrapidity, falling off with centrality and increasing |eta|. These results call into question the common assumption of longitudinal boost invariance over a large region of rapidity in RHIC collisions.

Journal Article↗
PubMed2002

Nanostructure and thermoelectric properties of ReSi 2+/-x thin films.

Anomalies in the nanostructure evolution of ReSi(2+/-x) thin films have proved to be of large interest in connection with their thermoelectric properties. By means of electron microscopic methods the correlation between structural properties and transport behaviour has been studied. The short-range order of the amorphous state was characterised by reduced density functions calculated from diffuse electron diffraction diagram and is found to correlate with the temperature dependence of the electrical resistance. The crystallisation process observed in situ in the transmission electron microscope starts with the formation of relatively large ReSi(1.75) grains (up to 100 nm). In later stages, only smaller grains are growing. This leads to a decrease in the mean grain size and to the increase of the nanocrystalline volume fraction during the heat treatment. This behaviour allows the investigation of the thermopower as function of the nanocrystalline volume fraction. Thus, at a nanocrystalline content of about 35% the thermopower exhibits a maximum in accordance with calculations.

Journal Article↗
PubMed2002

Model investigations on the effect of Si transport on the nanocrystallization of amorphous FeSiB-(Cu,Nb).

Amorphous material of the class FeSiB-(Cu,Nb) has been investigated with a background of soft-magnetic application of the corresponding nanocrystalline material. Thin-film analytical methods (SIMS, AES, TEM) have been used to study the diffusion of Si in such materials prepared as layer systems by magnetron sputter deposition. Significant interdiffusion occurs even at low temperatures - approximately 400 degrees C. Quantitative description failed, however, because formation of new iron monosilicide phases begins above this temperature. It is concluded that only high-mass-resolution SIMS or radioactive tracer analysis can be used for successful acquisition of information at this material system.

Journal Article↗
PubMed2001

Energy dependence of particle multiplicities in central Au+Au collisions.

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at root square[s(NN)] = 200 GeV. For the 6% most central collisions, we obtain dN(ch)/d(eta)/(/eta/<1) = 650+/-35(syst). Compared to collisions at root square[s(NN)] = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

Journal Article↗
PubMed2001

Ratios of charged antiparticles-to-particles near mid-rapidity in Au + Au collisions at sqrt[s(NN)]=130 GeV.

We have measured the ratios of antiparticles to particles for charged pions, kaons, and protons near mid-rapidity in central Au+Au collisions at sqrt[s(NN)] = 130 GeV. We observe / = 1.00+/-0.01(stat)+/-0.02(syst), / = 0.91+/-0.07(stat)+/-0.06(syst), and / = 0.60+/-0.04(stat)+/-0.06(syst). The / and / ratios give a consistent estimate of the baryo-chemical potential mu(B) of 45 MeV, a factor of 5-6 smaller than in central Pb+Pb collisions at sqrt[s(NN)] = 17.2 GeV.

Journal Article↗
PubMed2000

Investigation of thermoelectric silicide thin films by means of analytical transmission electron microscopy

The microstructure of rhenium silicide thin films and its progress by annealing were investigated by means of analytical transmission electron microscopy. Sputtered amorphous films were characterised by analysis of the radial distribution function (RDF). The position of the first maximum of RDF represents the most probable distance between neighbouring atoms and decreases from 2.75 to 2.62 A in films with an increasing Si-content from 60 to 75 at%. This decrease correlates with the change of the temperature coefficient (TC) of the electrical resistivity. During in situ annealing, the formation of nanocrystals in films with different Si-contents was observed. In thin films with 64 at% the quantity of nanocrystals increases after 1 h at 900 K whereas their sizes remain unchanged. The crystallisation in Re-rich thin films proceeds lower and produces larger crystals than in films near to the ReSi1.75 stoichiometry. Sputtered epitaxial ReSi1.75 films on Si (1 0 0) consist of crystals with nanometer size and an azimuthal torsion of 45 degrees.

Journal Article↗
PubMed2000

Can traumacel be used in the treatment of chronic wounds?

Traumacel (calcium salt of oxidised cellulose) has previously only been used in the treatment of acute wounds. To assess its safety and effectiveness in the management of chronic wounds a 12-week pilot study was undertaken which involved 11 patients with 15 non-healing leg ulcers and assessed ulcer size, ulcer pain and degree of exudate. Five ulcers healed within the study period. Significant pain relief was experienced by three patients. Use of the dressing did not appear to be related to a reduction in exudate. No patients experienced sensitisation to the product or had to be withdrawn because of adverse effects. Traumacel was found to be safe in the management of chronic ulceration, and appeared to promote healing in some recalcitrant ulcers.

Aged↗
PubMed1998

Oedema and its treatment.

Bandages have been applied to leg ulcers for centuries, but it is only comparatively recently that the relationship between oedema reduction and ulcer healing has been recognised. Oedema inhibits the microcirculation, preventing adequate perfusion and nutritional exchange.

Bandages↗
PubMed1997

Pain in venous leg ulcers.

A prospective study was conducted to assess the prevalence, severity and diagnostic utility of pain in patients with venous leg ulcers. A semi-structured questionnaire was completed by 140 consecutive patients in two specialist centres caring for patients with leg ulcers. A high proportion (64%) of the 94 patients with ulcers of purely venous aetiology reported severe pain; 50% of these patients were taking either mild analgesia or none at all. In 10 of 72 cases, leg elevation made the pain worse. Venous ulcers are painful. Pain in three distinct locations was reported by patients-within ulcers, around ulcers and elsewhere in the leg. The presence of severe pain does not necessarily indicate arterial disease or infection. Pain is, in general, inadequately controlled in these patients.

Adult↗
PubMed1994

A consultancy service that pays dividends. Setting up a pressure sore resource group.

1. The recognition that there may be a pressure sore problem in your hospital is important. 2. When starting a project, it is important to establish a baseline from which progress can be measured. 3. Better results will be achieved if the pressure sore problem is tackled by the multidisciplinary team. 4. It is important to realise that quality care costs money--the hospital may have to spend money in the first instance to provide a cost-effective service in the long run. 5. It is vital that medical and nursing staff are made aware of the cost-effectiveness of the wound care products they choose.

Consultants↗