Chunking as a rational strategy for lossy data compression in visual working memory.

The nature of capacity limits for visual working memory has been the subject of an intense debate that has relied on models that assume items are encoded independently. Here we propose that instead, similar features are jointly encoded through a "chunking" process to optimize performance on visual working memory tasks. We show that such chunking can: (a) facilitate performance improvements for abstract capacity-limited systems, (b) be optimized through reinforcement, (c) be implemented by center-surround dynamics, and (d) increase effective storage capacity at the expense of recall precision.

Knee-laxity measurements examined by a left-hand- and a right-hand-dominant physiotherapist, in patients with anterior cruciate ligament injuries and healthy controls.

The purpose of the study was to analyse and compare KT-1000 knee laxity as examined by a left-hand- and a right-hand-dominant physiotherapist in a group of patients with an anterior cruciate ligament (ACL) injury and a group of patients, 2 years after ACL reconstruction. The other aim was to measure and analyse knee laxity in a group of persons without any known knee problems. A cross-sectional examination of two groups of patients pre-operatively and post-operatively after ACL reconstruction and examination of healthy controls on two different occasions was performed.

Effect of expedited treatment of sex partners on recurrent or persistent gonorrhea or chlamydial infection.

Background: Many sex partners of persons with gonorrhea or chlamydial infections are not treated, which leads to frequent reinfections and further transmission.

Methods: We randomly assigned women and heterosexual men with gonorrhea or chlamydial infection to have their partners receive expedited treatment or standard referral. Patients in the expedited-treatment group were offered medication to give to their sex partners, or if they preferred, study staff members contacted partners and provided them with medication without a clinical examination.

Failure of family-planning referral and high interest in advanced provision emergency contraception among women contacted for STD partner notification.

Background: Few data are available on the risk of unintended pregnancy in women with STD or how contraceptive services can be integrated into STD control activities.

Objective: To define the risk for unintended pregnancy and assess the effectiveness of family-planning (FP) referral and interest in advanced provision emergency contraception (APEC) among women with gonorrhea or chlamydial infection.

Methods: Female participants in a randomized trial of different approaches to partner notification were interviewed, offered referral for FP services and asked if they would want APEC.

Rescreening for gonorrhea and chlamydial infection through the mail: a randomized trial.

Background: Rescreening patients after treatment of Chlamydia trachomatis or Neisseria gonorrhoeae infection has had high yield but low rates of participation.

Goal: The goal of this study was to determine if rescreening for gonorrhea and chlamydial infection in a largely urban sexually transmitted disease population would be more successful if individuals were given the option of submitting a specimen for testing through the mail.

Study Design: We conducted a randomized clinical trial involving 122 patients of whom 62 were assigned to clinic rescreening and 60 were given the option of either mailing a specimen for testing or going to a clinic for rescreening.

The beta-subunit of the protein-conducting channel of the endoplasmic reticulum functions as the guanine nucleotide exchange factor for the beta-subunit of the signal recognition particle receptor.

Cotranslational protein transport to the endoplasmic reticulum is controlled by the concerted interaction of three GTPases: the SRP54 subunit of the signal recognition particle (SRP) and the alpha- and beta-subunits of the SRP receptor (SR). SRbeta is related to ADP-ribosylation factor (ARF)-type GTPases, and the recently published crystal structure of SRbeta-GTP in complex with the binding domain of SRalpha suggested that SRbeta, like all ARF-type GT-Pases, requires a guanine nucleotide exchange factor (GEF) for function. Searching the sequence data base, we identified significant sequence similarity between the Sec7 domain of ARF-GEFs and the cytosolic domains of the beta-subunits of the two homologous heterotrimeric protein-conducting channels in yeast.

Architecture of the protein-conducting channel associated with the translating 80S ribosome.

In vitro assembled yeast ribosome-nascent chain complexes (RNCs) containing a signal sequence in the nascent chain were immunopurified and reconstituted with the purified protein-conducting channel (PCC) of yeast endoplasmic reticulum, the Sec61 complex. A cryo-EM reconstruction of the RNC-Sec61 complex at 15.4 A resolution shows a tRNA in the P site.

Remifentanil and fentanyl during anaesthesia for major abdominal and gynaecological surgery. An open, comparative study of safety and efficacy.

Background: and objective This open, multicentre study compared the efficacy and safety of remifentanil with fentanyl during balanced anaesthesia with 0.8% isoflurane (end-tidal concentration) for major abdominal and gynaecological surgery, and the efficacy and safety of remifentanil for pain management in the immediate postoperative period.

Methods: Two-hundred and eighty-six patients were randomized to receive remifentanil 1 microg kg(-1) followed by 0.

[Meperidine (pethidine) outdated as analgesic in acute pancreatitis].

The most important symptom in acute pancreatitis is pain. This pain often is so severe that treatment is started with opioid analgesics. In daily practice meperidine is often the analgesic of first choice because it is supposed to cause less spasm of the M.

Oral dolasetron mesylate for prevention of postoperative nausea and vomiting: a multicenter, double-blind, placebo-controlled study. The Oral Dolasetron PONV Prevention Study Group.

Study Objective: To examine the safety and effectiveness of a range of single oral doses of dolasetron mesylate for the prevention of postoperative nausea and vomiting.

Design: Randomized, double-blind, placebo-controlled trial.

Setting: 32 hospitals.

Sufentanil pharmacokinetics in young adult and elderly surgical patients.

Sufentanil 3 microgram kg-1 was administered as an intravenous (i.v.) bolus to 12 elderly patients, aged 65-87 years and 12 young adults, 17-43 years of age, all ASA class I-II, scheduled for orthopaedic surgery.

A single i.v. dose of ondansetron 8 mg prior to induction of anaesthesia reduces postoperative nausea and vomiting in gynaecological patients.

The effect of a single intravenous dose of ondansetron in preventing postoperative nausea and emesis (retching and vomiting) (PONV) was investigated in a randomized, double-blind, placebo-controlled, multicentre, international study. Women of ASA class I-III, requiring gynaecological laparotomy, vaginal hysterectomy, or major vaginal surgery were selected for study. Two hundred and thirty-five received placebo, 231 received 1 mg ondansetron, 228 received 8 mg ondansetron and 229 received 16 mg ondansetron, as an infusion over five minutes before the induction of anaesthesia.

Oral ondansetron in the prevention of postoperative nausea and vomiting.

The effect of three times daily oral ondansetron in preventing postoperative nausea and vomiting was investigated in two randomized, double-blind, placebo-controlled, multi-centre studies. The first study compared ondansetron 1, 8 and 16 mg to placebo, and the second study compared 8 mg ondansetron to placebo. Both studies included ASA Class I-III female patients about to undergo major abdominal gynaecological surgery or vaginal hysterectomy.

Comparison of intravenous and intranasal sufentanil absorption and sedation.

The absorption and sedation following an intranasal dose of sufentanil were evaluated and compared with those of the same dose given intravenously. Sixteen adult patients scheduled for elective surgery were randomly allocated to receive as premedication 15 micrograms sufentanil either intravenously or intranasally. Before administration and at fixed time intervals thereafter, the degree of sedation was assessed, vital signs were recorded and venous blood samples were taken for the determination of sufentanil plasma concentrations.

[A sufentanil dosage study in general surgery].

Sufentanil is widely used for cardiac surgery in initial doses up to 15 micrograms/kg. It was expected that for general surgery much smaller doses would be appropriate. The aim of the study, therefore, was to find a dosage scheme for sufentanil that could be used in general surgery for operations lasting 1 h.

Recovery from fixed-dose midazolam-induced anaesthesia and antagonism with flumazenil for outpatient arthroscopy.

This study evaluated recovery after a fixed dose of midazolam as induction agent and the influence of flumazenil on recovery parameters in patients undergoing day-case surgery (arthroscopy of the knee). In 40 unpremedicated patients, anaesthesia was induced with midazolam 0.2 mg/kg, vecuronium bromide 0.

Recovery from propofol infusion as the main agent for outpatient arthroscopy. A comparison with isoflurane.

Propofol by continuous intravenous infusion has been compared with isoflurane as the main anaesthetic agent for outpatient arthroscopy of the knee. In 40 unpremedicated patients, anaesthesia was induced with propofol 2 mg/kg and vecuronium bromide 0.1 mg/kg and maintained after tracheal intubation with nitrous oxide 66% in oxygen.

Alfentanil used in the aged: a clinical comparison with its use in young patients.

The clinical effects of an i.v. bolus dose of 50 micrograms kg-1 alfentanil were studied during surgical anaesthesia in 10 elderly patients and compared with those of the same dosage in nine young adults.

Effect of etomidate on cortisol biosynthesis: site of action after induction of anaesthesia.

To determine the site of inhibition of etomidate on cortisol biosynthesis, plasma cortisol, aldosterone, 17 alpha-hydroxyprogesterone, 11-deoxycortisol and ACTH levels were measured in healthy women before and after the administration of a single dose of either 0.20 mg kg-1 etomidate (mean value, n = 10) or 3.15 mg kg-1 thiopental (n = 9) for induction of anaesthesia in a randomized trial.

Alfentanil analgesia for surgical procedures of medium and long duration.

The clinical potential of alfentanil, a short acting narcotic analgesic as a supplement to only nitrous oxide/oxygen was evaluated in 141 patients having surgery of medium and long duration. Following induction of anesthesia with thiopentone alfentanil 1 mg was injected just prior to intubation. Anesthesia was maintained with a mixture of nitrous oxide/oxygen, (2:1) with analgesia achieved by a loading dose of alfentanil 0.

[Continuous alfentanil infusion in surgical interventions of intermediate and long duration].

Alfentanil, a new short-acting narcotic analgesic, was studied as a continuous infusion for surgical procedures of medium and long duration in 80 patients. Anaesthesia was induced with thiopentone immediately followed by 1 mg of alfentanil to attenuate the stress response to intubation. Alfentanil 100 micrograms/kg was then slowly given as a loading dose before surgery started and anaesthesia maintained by a continuous infusion at a rate of 0.

Total intravenous anesthesia with etomidate, alfentanil and droperidol.

Forty-six women admitted for gynecologic surgery, were given alfentanil 1 mg, droperidol 2.5 mg and etomidate 0.3 mg/kg body weight intravenously for induction.